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Engine Specific Info and Questions => IDI Engine => Topic started by: Gizmoman on December 25, 2013, 08:27:26 am
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I now have about 200 miles on the rebuild. I had a loose hose clamp on the new silicone heater hose going to the hater valve under the dash. When I got home,I noticed water dripping from the passenger door opening and soggy carpet. I checked the overflow tank and it was empty - the pressure tank was completely full though. I'ts all fine now but as it's a hard to bleed Vanagon, I re-checked for air bubbles using the libby-bong method. For some reason, the water temps are getting into the 200+ range and it has me quite worried.
The details are:
New 185* thermostat
Temps are 175-185 tooling around town
Freeway driving at 65 (3200 RPM 7-8 lbs of boost) gets temps to 200 pretty rapidly. As soon as I exit, temps come back to 180 fairly quickly.
The radiator is brand new and the fan was coming on a few days ago but I haven't heard it recently. Even if it was the fan not turning on, I would think freeway speeds and ambient temps in the high 40's would keep it cool - just makes no sense.
I have new SS pipes under the van.
I made a restrictor disc (with a 1/4" hole in the center) which I installed in the upper hose to the pressure tank.
The water in the tank swirls around quite a bit when I rev the engine - not sure if this is normal or not. Hopefully, I don't have a blown HG.
Head studs are ARP torqued to 125 ft/lbs (as per instructions). I have not re-torqued them.
This is really upsetting after all the work I've done. From what I have read, the cooling system is quite adequate for this engine - something just isn't adding up. Maybe I have the hoses to the radiator mixed up or something stupid like that. The new radiator has both ports on the bottom but I posted about it previously and am fairly confident I now have them correct http://www.vwdiesel.net/forum/index.php?topic=34048.0 (http://www.vwdiesel.net/forum/index.php?topic=34048.0). Or maybe I need to re-torque the head studs :(
Any help appreciated.
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Unless you lose coolant I would not touch the studs. The studs and metal gasket will probably never blow out. 200 isn't bad.
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Is the gauge accurate?
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Unless you lose coolant I would not touch the studs. The studs and metal gasket will probably never blow out. 200 isn't bad.
Thanks for the response - especially on Christmas day!
IMHO 200 is more than it should be unless I were really pushing it hard - I'm not - just cruising. The system should keep it at least below 190. When it hits 200, I'm confident it would just keep going if I didn't back off. Somehow I must still have air in it. I just checked it with a heat gun after doing a hard run around the block. The pressure tank is at 180 but the radiator near the fan switch is only 117. I jumped the fan and it runs fine. Obviously something is wrong with the cooling system (most likely air). I checked the v-belt tension in case the pump wasn't turning as it should, but it feels tight.
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Is the gauge accurate?
I believe the digital gauge is very accurate. It reads from a probe and was quite expensive (if that means anything). The stock gauge on the dash has no numbers but typically never went far past the red warning light in the center. Now it's getting to the 3/4 mark which is much higher than it ever used to get. I know it would keep going if I didn't back off a bit.
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PER CRSMP5 advice I run the coldest thermostat 80c I believe. I can hammer it good for awhile before the temps starting rising.
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PER CRSMP5 advice I run the coldest thermostat 80c I believe. I can hammer it good for awhile before the temps starting rising.
That makes sense. I don't recall what temp unit I put in but I believe it may have been the hotter one which would explain a lot.
Dang, have to bleed the cooling system again!
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I don't think I've had any automotive component bad out of the box more than thermostats.
My first attack would be with an IR Pyrometer to confirm the temp gauges reading, and follow coolant flow as indicated by steadily decreasing temps as you go down the line, looking for an appropriate drop across each component. I have a fancy one, but the $35 harbor freight one is probably just as good if you don't need to measure over 500*F
Your symptoms sound to me like a stat that doesnt open, or not fully, and is fine so long as you stay under about 30% throttle?
Another possibility is as the stat builds up to temp, it spikes and gulps cold from the rad till the system equalizes, and you just didn't drive far enough for that to happen?
many cars have a temp compensating board in the gauge to hide this effect, and all my large coolant capacity rigs do it to some extent.
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I have shot an infrared probe at it in several locations after a run and found the pressure tank at 180, the head at 212 and the rad bottom around 130 with the top at 175.
Just went for another jaunt this evening and am beginning to narrow it down to a possible issue. . . It seems my IC isn't cooling (again) and this time it's not the hose size. There's water in it but the air sensor is giving me high readings again. I'll have to check the pump. It's one of those Bosch jobs and cannot pull any water at all - needs to be flooded suction. One air bubble and it stops moving water. I believe the way the pump is tuned, an IC is required and this one is not cutting it.
I did back off the fuel screw 1/8 turn, but promptly turned it back to it's "Giles location" - it really took out the bottom end.
I was hoping to drive it to work tomorrow but not till it's right and I'm not sure what that will require. Right now I'm leaning towards a new frozen boost IC and a new intake manifold.
I did find the top half of the one I butchered in my aluminum scrap, maybe I can just tig the two back together ;D
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What brand is the t-stat and where are you picking temp from?
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I have my entire front of the rad blocked, like even beside the radiator on both sides overlapping the headlights.
When I got on it on the highway, I saw temps leaving the head of 225F, I wasn't too alarmed. I run a 160F thermostat too. Flip the rad fan on for 30 seconds, right back down to 190. It was cruising the highway at 205-210, and lemme tell you the HEAT coming from the dash was GLORIOUS!
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Don't worry about the brand of the thermostat, just chuck it in a tub of boiling water and watch it not open.
I was pretty pissed when my $45 Wahler didn't open. Drove around 3 days under 1/3 throttle hoping to clear a nonexistent air bubble.
As an IC test, blow some water/meth preturbo... If it doesn't help, more IC work probably won't fix it.
It does sound like your IC pump should be located in a bottom hose area though. I happen to know a sump pump on a Home depot 800W inverter moves a pretty good volume from a bucket(test reservoir).
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YEA GIZ maybe a water meth system would be nice for you to have?
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What brand is the t-stat and where are you picking temp from?
Don't know what brand it was. I am getting the temp from the hose coming from the head (see probe in photo below), so I would expect it to be high. The stock Vanagon gauge is reading 1/4 over what it used to though (3/4's of the gauge)
(https://lh4.googleusercontent.com/-7cqt84-RUlc/UoAdlQJVDZI/AAAAAAAACVg/KEB4_r2zUqk/w960-h720-no/DSC00676.JPG)
Don't worry about the brand of the thermostat, just chuck it in a tub of boiling water and watch it not open.
I was pretty pissed when my $45 Wahler didn't open. Drove around 3 days under 1/3 throttle hoping to clear a nonexistent air bubble.
As an IC test, blow some water/meth preturbo... If it doesn't help, more IC work probably won't fix it.
It does sound like your IC pump should be located in a bottom hose area though. I happen to know a sump pump on a Home depot 800W inverter moves a pretty good volume from a bucket(test reservoir).
I just verified that the IC pump is running and moving water so I'm back to guessing. I suppose I will have to dump the coolant and check the thermostat. I seriously doubt it's the issue but don't know what else to do at this point. It runs great until I start pushing it - even a small amount. What's odd is that after the larger IC hose upgrade, it was fine - then it wasn't. It runs like it did before the hose change and IC temps are back where they were as well. It really seems like if I could cool off the IA, it would keep the temps down (like it did for a day).
The only odd duck here is the IC I built. It's butt engineering at it's finest with no flow testing. Just rude and crude - hmmm, that should work 8) A Frozen boost IC would at least rule it out but I have no Idea where I would locate the thing near the engine and keep the air flow simple. The nice thing about what I made is the turbo plugs directly into it.
YEA GIZ maybe a water meth system would be nice for you to have?
I designed a nice system for water/meth and have a 200 psi pump, adjustable pressure switch, nozzles, etc, etc. The problem arises when you consider travelling accross country and going from Home Depot to Home Depot mixing the crap up with distilled water. Not to mention another tank, wiring, hoses, blah blah bla. There's something wrong and like I said the IC is the oddball. The thermostat is fairly easy to check so I'll start there.
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For as much money as I see in that one photo, I'd be PO'd too.
Very nice work.
Test any t-stat before install, and don't use parts store stuff. Behr or Wahler.
And not all waterpumps are created equal either.
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For as much money as I see in that one photo, I'd be PO'd too.
Very nice work.
Test any t-stat before install, and don't use parts store stuff. Behr or Wahler.
And not all waterpumps are created equal either.
Thanks. ;)
Interesting you'd comment on the water pump I don't recall the brand I purchased but it is new. I ran across a thread where a guy mentioned that the ones with the cheezy sheet metal impeller actually worked better than the original one he had. Apparently the stock pump had a fancier looking plastic impeller which is NLA.
I know the new radiator I installed is much better than the old stocker I had. There's no reason this thing should be getting hot unless the water isn't moving fast enough. (or the thermostat isn't opening up all the way).
Something changed somewhat abruptly though. As I said, I'll check the thermo but I think a new intake manifold and a proven IC is in order.
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Did your hose sizes and routing change from before (when it was not overheating)? You mentioned both ports of your radiator is on the bottom? That's just wrong and can't possibly work well. Can you post a pic of the rad?
Very nice looking engine compartment. One comment about those injector return lines (the yellow ones). I was given some that looked very similar and used them for about a year when one of them popped off spilling fuel all over. Mine were the exact same color, Tygothane made for fuel per the fella who gave them to me. They were kind soft and very easy to push onto the barbs. Thought I mention it. Not saying you will have the same experience.
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Another comment on the engine pic. No clamp on the coolant expansion tank clear hose? Is it a pressurized system? If so, I'd put a clamp there.
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Did your hose sizes and routing change from before (when it was not overheating)? You mentioned both ports of your radiator is on the bottom? That's just wrong and can't possibly work well. Can you post a pic of the rad?
Both connections are at the bottom of the vanagon radiator but one of the connections has an open tube running up to the top of the rad. That said, the flow through the vanagon radiator is the reverse of almost all other automotive radiators with the hot coolant entering the BOTTOM and the cooled coolant exiting the TOP to return to the engine. That routing actually works extremely well and is necessary in order to purge any air from the radiator.
I've used tygothane hose on a large number of engines for several years without issue. It is the best hose I have used.
The line from the vanagon expansion tank cap is not under any pressure and would not affect the operating temperature in any way even if not present.
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For as much money as I see in that one photo, I'd be PO'd too.
Very nice work.
Test any t-stat before install, and don't use parts store stuff. Behr or Wahler.
And not all waterpumps are created equal either.
Thanks. ;)
Interesting you'd comment on the water pump I don't recall the brand I purchased but it is new. I ran across a thread where a guy mentioned that the ones with the cheezy sheet metal impeller actually worked better than the original one he had. Apparently the stock pump had a fancier looking plastic impeller which is NLA.
I know the new radiator I installed is much better than the old stocker I had. There's no reason this thing should be getting hot unless the water isn't moving fast enough. (or the thermostat isn't opening up all the way).
Something changed somewhat abruptly though. As I said, I'll check the thermo but I think a new intake manifold and a proven IC is in order.
That was probobly me, I had a chance a few years ago to do a back to back with the molded looking composite impeller and the cheap crappy looking stamped one, and the stamped
jobby cooled better in every respect. Go figure. It was GAF of Hepo or Hippo or what the heck ever it is that SSF/WorldPac sell for them.
That isn't to say the molded/composite impeller cannot cool well enough, just I saw more favorable gauge movement with the stamped style.
And I've personally seen more than a few composite impellers fall apart and cease to function prior to weeping coolant outward, but that's usually a
can-o-worm in itself.
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Another comment on the engine pic. No clamp on the coolant expansion tank clear hose? Is it a pressurized system? If so, I'd put a clamp there.
The hose is quite tight and is under no pressure. It does have a bit if vacuum at times sucking the coolant from the overflow tank back into the pressure tank when it cools off. Seems to work fine.
The tygothane is holding up as well, It is a bit soft and if you smack it just right with a wrench where it's connected, it can get cut, but I have not had any leaks at all.
The pic was posted to show where the temp probe for the coolant was located. I appreciate the comments on how it looks but that wasn't the point. Frankly I'd rather it was ugly and not overheating ;D As I've said, a proven IC (instead of my home made one) is a good possibility in the near future - just have no idea where I am going to put it and how I will find room to run 2-1/2" piping.
I am wondering if the turbo is leaking oil past the seals and has blown it into my IC. If that were the case it may result in the high intake air temps I am seeing, as the tiny fins would be plugged. I'll check it out this weekend.
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Do not run the 2.5" piping, run 2". The 2.5" will have more ultimate flow, but again velocity is key to good snap off the bottom and the 2" will be better for everything except running wide open and high rpm.
The water pumps have been looked at and the plastic impellers are bad. The stamped and cast have their own benefits. I cannot remember for sure which one is better where. CRSMP5 knows as he had a temp probe installed in a different location. All I remember is that the cast impeller lowers cylinder head temps a few degrees over the stamped one.
Also, did you use the water wetter type stuff?
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I know it seems crazy, nonsensical etc, and I don't want to hear anyone telling me it shouldn't have an effect,but my pal Steve, who is very smart had a similar issue with his AAZ, water cooled IC Vanagon. WE did find a crack in his block at first,though for sure we found the issue[changed the short block], but after a long trip to Newfoundland, the overheating resurfaced. The one thing that had a direct,immediate effect was his checking and adjusting the internal pump pressure. I wish I could remember if it was too high or low, but it did fix his problem. Again not exactly the same condition you are having, but just a heads up that some problems are not so obvious. Now if I could only figure out why my AHU Jetta blows out coolant when rolling off the highway, but only when it's below -15oC
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oh yeah, you will need to rebleed it again if you haven't already
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Do not run the 2.5" piping, run 2". The 2.5" will have more ultimate flow, but again velocity is key to good snap off the bottom and the 2" will be better for everything except running wide open and high rpm.
The water pumps have been looked at and the plastic impellers are bad. The stamped and cast have their own benefits. I cannot remember for sure which one is better where. CRSMP5 knows as he had a temp probe installed in a different location. All I remember is that the cast impeller lowers cylinder head temps a few degrees over the stamped one.
Also, did you use the water wetter type stuff?
Thanks for the pipe size advice. 2" will be easier to route through my tight space for sure, and low end punch is definitely a goal. My only concern would be the restriction of air volume. At 65 mph (32-3400 RPM), I'm running between 7-12 lbs of boost and living in So Cal, freeways are the norm (ug). As for the water pump, I'm fairly confident my new one has the sheet metal impeller. BTW, I did use the water wetter stuff in both the IC and engine coolant. No idea if it helps as I have to comparison - just took your word for it ;)
I know it seems crazy, nonsensical etc, and I don't want to hear anyone telling me it shouldn't have an effect,but my pal Steve, who is very smart had a similar issue with his AAZ, water cooled IC Vanagon. WE did find a crack in his block at first,though for sure we found the issue[changed the short block], but after a long trip to Newfoundland, the overheating resurfaced. The one thing that had a direct,immediate effect was his checking and adjusting the internal pump pressure. I wish I could remember if it was too high or low, but it did fix his problem. Again not exactly the same condition you are having, but just a heads up that some problems are not so obvious. Now if I could only figure out why my AHU Jetta blows out coolant when rolling off the highway, but only when it's below -15oC
I am open to nonsensical at this point. Man I hope the block is OK. It's not the original, I won't go into why right now but it is a factor I hadn't considered. I suppose a leak-down is in order but am not sure how to go about doing one. Geeze, if this block is cracked I am seriously going to be pissed - at the moon though cause it would be no one's fault buy mine for not having it checked somewhere.
As for checking the pump pressure, I assume you mean the IP? If so, it's a Giles pump and I've backed of the fuel screw an eighth, then promptly put it back due to a huge loss of low end. Who knows, maybe I over-shot it and I am adding more fuel than I was ??? Also, not sure how to change the pressure and even if I did, I won't.
I really have to trust what Giles did to the IP. I spoke with him at length (nice guy by the way) before sending it to him and was clear in what I was looking for. "Application; Vanagon AAZ 1.9TD, K14 turbocharger @15 lbs max boost, Goal: 120 to 150 MAX HP, with a focus on dependability". I was providing an IC and expect he "tuned" for that. What he may not have tuned for was an IC running around 40% efficiency (at best). - I need to hold up my end of the bargain.
If you meant "water pump", forget everything I just said ;D
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Back off the boost/fuel and see if it still runs hot? Kinda simplistic but hey. EGT's high? I might have missed if you listed them.
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I pulled the thermostat and checked it on the stove. My heat gun shows it opens completely around 188 F. It doesn't move much till then. It closes slowly as it cools and is fully closed at 165 F. I ordered one that opens at 180 but I don't think this is the issue.
After doing a lot of Googling "AAZ overheat", some folks have had issues with backwards vanes in their pumps. Some were designed to run off the back-side of a serpentine belt. I am running a v-belt so the pump turns the same direction as the crank.
Here is a shot of the new pump I installed during the rebuild.
(https://lh5.googleusercontent.com/-977YhQPNq3c/Ur8AWLMQJmI/AAAAAAAACVw/G95mp56XkPA/w960-h720-no/DSC00716.JPG)
Looks like a cast impeller
Here's the previous pump - nothing wrong with it, just wanted a new one for the "new" engine.
(https://lh6.googleusercontent.com/-SHugMOAoam8/Ur8AW3G-qbI/AAAAAAAACV0/MV8jkXU_Jy8/w960-h720-no/DSC00718.JPG)
Obviously the previous pump has the sheet metal impeller. I'm not sure if the new pump (first photo) has the vanes going the right direction though.
Opinions?
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I case you have exhausted all other possibilities and may suspect the block or head have a crack, the only way we finally found it was using a tester which checks for combustion gas in the coolant> I have a Snap-on one, but I think other companies make them.
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The new pump impeller sure seems to sit a lot deeper into the thermo housing...Is it on the shaft all the way? restricting itself?
IMO your thermo readings on the radiator indicated that the too hot coolant was neither getting to nor overwhelming the radiator.
I don't know how hard your access is, on my car it's dead easy, and when I suspect a thermostat, I pin one all the way open, install it and go for a drive.
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Went to Napa and bought a "block tester" which will help determine if I'm getting combustion gasses into my coolant. It's supposed to go into the radiator filler neck but since I don't have one on the van, I'll have to check it at the pressure tank. The pressure tank is lower than the top of the radiator so I'll use a 2-1/2" ABS pipe and rubber reducer to extend the check above the radiator (kinda like a libby bong without the drain hose at the bottom). The tester is supposed to only check the air above the coolant and should not contact the coolant itself.
I also bought a new thermostat as the new one I had seemed to open at 185-190. The new one opens at 180. Yes, I tested them both on the stove.
I'm wondering which of the two pumps move more water, the cast impeller or the sheet metal one. Before I go to the trouble of filling the system again and bleeding out the air, now would be a good time to change it - just not sure which one flows the most. The cast impeller appears to have closer tolerances to the housing but smaller vanes. The sheet metal one has longer vanes but also has more clearance from the housing.
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The cast metal impeller moves more water than the stamped steel impeller. My temp gauge went up a little after replacing a cast impeller pump (w noisy bearing) with a stamped steel one.
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I think your impeller might not be pressed all the way on.
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The aaz's never had a water pump that ran off of the serpentine belt. It was always on v-belt with the power steering as well. 1Z/AHU tdi's were the same too.
I do not think it is a backwards spinning problem because I have the same P/N water pump being spun by the back side of the serpentine belt on my AHU swap with no P/S.. And it moves coolant as it should, so that rules out that theory.
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Well, after all that, it did turn out to be the thermostat. The new one I put in is a 180 and the one that was in there was a 190 or possibly even higher. No numbers were stamped on it but when I tested it, it opened around 190. The new one has a larger diameter "gate" as well but I'm not sure if that helps or not. The temp probe is sensing coolant from the head and even when I push it, it's not going over 195. The stock gauge is riding dead center when cruising and moves slightly past the LED after a long climb - I'm a happy man.
Thanks for the feedback on the impeller. I left the cast one in place as it just looked more efficient - glad to hear that it is.
I also ran the combustion gas test and the fluid stayed blue. I did the test with the engine at 170F and pumped the vacuum bulb probably 50 times - stayed blue.
This is a real load off my mind. Now all I need to do is remove the valve cover and smear about a tube of silicone between everything. I've messed with it three times, putting blobs at the cam corners and all - no luck. It's the only leak I have and it's making a real mess of everything.
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Haha, careful.. some people swear RTV is the devil. Put a small bead, and let it "tack" before mating the assembly. This greatly reduces the amount of squeeze out the blocks oil pumps hhaa.
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Haha, careful.. some people swear RTV is the devil. Put a small bead, and let it "tack" before mating the assembly. This greatly reduces the amount of squeeze out the blocks oil pumps hhaa.
I won't get too carried away. Just seems like of all the things on this that could leak, the valve cover should not be one of them. I've tried dabs in the corners, thin coats, checked the stamped metal cover for flatness, etc.
Time to get serious. I will use the grey stuff which claims to be impervious to oil and feels much tougher than others when it sets.
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I thought VW engines tend to fall into two categories those that operate just over atmospheric boiling point of water and those that don't quite.
17-19psi running pressure + coolant additive takes boiling point significantly over boiling point. So, what's the problem?
As I've said before, try retarding pump a little. Don't 'Giles' pumps offer faster advance rates, and greater maximum advance, so starting slightly retarded from 'book' is not unreasonable IMO.
Why not just try it, measure the results and then go back if no improvement? The slight increase in heat out of the exhaust will be coupled with a bigger decrease in heatloss to coolant, and more pressure doing work ATDC, IMO...
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I thought VW engines tend to fall into two categories those that operate just over atmospheric boiling point of water and those that don't quite.
17-19psi running pressure + coolant additive takes boiling point significantly over boiling point. So, what's the problem?
Truth, when I was hitting 230F I was not at all worried. New hoses, new rad, new bottle and cap.. Had the coolant additive as well.. Nothing bad went wrong, didn't even burp any coolant.
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Hooray for cheap $easy solution, i thought you'd find that.
If you have the shouldered studs for the valve cover, be certain they are all sunk to the flange, or it will for sure leak, and be a pain to remove.
Has there been any change in EGT?
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Hooray for cheap $easy solution, i thought you'd find that.
If you have the shouldered studs for the valve cover, be certain they are all sunk to the flange, or it will for sure leak, and be a pain to remove.
Has there been any change in EGT?
I can still hit 1300 pretty quick getting on the freeway - typically a short climb to boot. My intake charge air temp (CAT?) still seems warmer than it should be but I'll live with it for now. The goal is dependability and only time will tell.
It's great to hear that the engine can get so hot without damage. Maybe I am a bit wary, but I can imagine the Mojave, a long climb, and in August no less. To me, if 180 is on the thermostat, and the system is up to snuff, 180 is where it should stay.
Really appreciate all the feedback and good info. Thanks again.
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Just to beat a semi-dead horse, brand of the old and new t-stats?
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GM doesn't even turn the fan on till 230(the thermostat is wide open long before that) on Vettes and Camaros, part of how they get such good highway MPG(and bake the hell out of the harness wrinkle wrap).
Brand? I think thermostats are just weak, and I've seen a dud from every brand.
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cast has been the better choice for me
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Remember that the thermostat opening temperature isn't the system operating temp, but the initial 'rapidly' achieved engine temp before the additional circulation of water occurs.
Then there's the hysteresis, allowing engine temp to drop, yet the gate remains [partly] open, then further, [higher rises] as the engine produces more heat. Otherwise interior heater would be cold to start followed by more noticeable pulses of hotter, then cooler air. Well that's my take on it ;D
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Just to beat a semi-dead horse, brand of the old and new t-stats?
Yeah, just beat it!
Old one - don't know, no stamp or nuthin (not a good sign). The one that fixed it - Duralast from the parts house on the corner - 16 bucks. They had a better brand listed for twice that but not in stock. It looks fine craftsmanship-wise and it passed the test on the stove. ;) Ironically, the one I ordered showed up today as well - after I got the local one in and the van running.
As far as high temps go, the stock gauge has always been the weather "vane" for me and it seems 180-190 is where it should be to keep the needle pointing straight up. More to the point, a stable temp is the most important if it's 180 or 225, it should be stable or something's not right.
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The thermostat is nothing at all like an on/off and instead maintains a very accurate coolant inlet temperature regardless of the temperature of the coolant in the radiator, right up to the point that the thermostat is wide open. The heater circuit is always open and flows freely regardless of thermostat position. The thermostat itself operates as a blending door for the other two water pump inlets; the bypass hose and the return from the radiator. The thermostat has a fairly wide opening range both in temperature and in the distance it moves. As it opens the return from the radiator, the other end of the thermostat simultaneously closes the bypass circuit.
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The thermostat is nothing at all like an on/off and instead maintains a very accurate coolant inlet temperature regardless of the temperature of the coolant in the radiator, right up to the point that the thermostat is wide open. The heater circuit is always open and flows freely regardless of thermostat position. The thermostat itself operates as a blending door for the other two water pump inlets; the bypass hose and the return from the radiator. The thermostat has a fairly wide opening range both in temperature and in the distance it moves. As it opens the return from the radiator, the other end of the thermostat simultaneously closes the bypass circuit.
Well put. And I believe that's why the temp should not change much. I have no idea why the previous "new" thermostat allowed it to vary so widely but the new, less expensive one seems to hold it quite steady.
If I had a decent IC or a VNT with the proper linkage, I'd be home free even under the most severe conditions. As it is, I'll just keep my foot out of it.
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Both my trucks with huge overkill cooling systems;
Diesel Dodge ~ 7 gallons for 165 HP
350 Chev ~ 500 CI Cadillac 4 core rad
exhibit the gulp of cold 2-3 times a few minutes apart before the water in the rad is warm enough for the thermostat to work stably.
I think quite a few cars do, but the damping in the OEM gauges keeps the driver form seeing it and becoming concerned.
Neither of the above rigs has ever gone 10*F over thermostat temp no matter what i've done.
The Volvo TD, and 6.2 Suburban TD both will heat up climbing at full load if you don't watch it, and have pretty stock cooling systems.
These two, back down till EGT drops 200 degrees, and you have no worries, they'll pull all day.
My Caddy went up to 2/3 on the gauge, and seized a ring, so I turboed it, and I don't think it ever overheated again unless it was blowing a headgasket.
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Interesting take on vnt control.
http://forums.tdiclub.com/showthread.php?t=401671
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I thought VW engines tend to fall into two categories those that operate just over atmospheric boiling point of water and those that don't quite.
17-19psi running pressure + coolant additive takes boiling point significantly over boiling point. So, what's the problem?
As I've said before, try retarding pump a little. Don't 'Giles' pumps offer faster advance rates, and greater maximum advance, so starting slightly retarded from 'book' is not unreasonable IMO.
Why not just try it, measure the results and then go back if no improvement? The slight increase in heat out of the exhaust will be coupled with a bigger decrease in heatloss to coolant, and more pressure doing work ATDC, IMO...
Thanks Mark, I agree, it is worth a try. Besides, I never even hooked up my diesel timing light I just had to have :o. Last I checked my timing was at .95 using the dial indicator. If it means anything, pulling out the cold start doesn't seem to change how it runs at all. I know there's no slack and it's working properly.
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The thermostat is nothing at all like an on/off and instead maintains a very accurate coolant inlet temperature regardless of the temperature of the coolant in the radiator, right up to the point that the thermostat is wide open. The heater circuit is always open and flows freely regardless of thermostat position. The thermostat itself operates as a blending door for the other two water pump inlets; the bypass hose and the return from the radiator. The thermostat has a fairly wide opening range both in temperature and in the distance it moves. As it opens the return from the radiator, the other end of the thermostat simultaneously closes the bypass circuit.
Here's a shot of a cold thermostat in the water pump housing (not that libby's description needs clarification ;)).
(https://lh6.googleusercontent.com/-FPpqopOSB3U/UsBCvXa_TII/AAAAAAAACWg/nmU-nzhoyfc/w960-h720-no/DSC00722.JPG)
Just for grins, the sheet metal and plastic impellers as well.
(https://lh6.googleusercontent.com/-AF1LEmY2Awk/UsBE-gL6OUI/AAAAAAAACWs/buSaJP7Da7k/w960-h720-no/DSC00723.JPG)
The housings themselves (including the one with the cast vanes) all appear to be identical. The one with the plastic impeller has the closest fit to the housing and I believe was the original one that came from VW (NLA). The sheet metal one has the worst fit to the housing of the three. IMHO, the Vanagon application has to move water a long way to reach the radiator, so a high flow/high pressure pump would be best. As the cast impeller is the closest fit to the housing, it makes sense that it is the preferred choice of the only two styles available. I'd be interested in doing a test but just don't have time right now.
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So everyone agrees then; that the thermostat doesn't switch in and out, and helps to regulate heat to the heater, by sending differing amounts to the radiator. Still varies a bit though...
Strange how the mk2 on Golf stuff did away with the adjustable valve to the heater, and relied on a sponge seal on a flap, but the Quantum/Audi range retained it.
Still, the original point was that the operating temp of the thermostats are not the operating temperatures of a healthy engine...
0.95 setting for the AAZ is higher than any book value, so although it may be fine for your engine; retarding in your case will not appear as extreme as in my engine, and will likely help your engine temperature issue... at less than the cost of some of your proposed alternatives ;D
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So everyone agrees then; that the thermostat doesn't switch in and out, and helps to regulate heat to the heater, by sending differing amounts to the radiator. Still varies a bit though...
Strange how the mk2 on Golf stuff did away with the adjustable valve to the heater, and relied on a sponge seal on a flap, but the Quantum/Audi range retained it.
Still, the original point was that the operating temp of the thermostats are not the operating temperatures of a healthy engine...
0.95 setting for the AAZ is higher than any book value, so although it may be fine for your engine; retarding in your case will not appear as extreme as in my engine, and will likely help your engine temperature issue... at less than the cost of some of your proposed alternatives ;D
The van has foam covered flaps as well - well they were foam covered 30+ years ago ;)
Not sure I agree with you on the operating temps being much different than the thermostat. My change of units just proved that. While I am going slightly over 180, it's not much over. And when it is, I believe it's a result of the system not keeping up with the new HP (energy = heat).
I'll give your pump adjustments a go (probably next weekend) and report back. What number(s) do you suggest?
I just re-caulked my valve cover and wanted it to set up for 24 hours before I dump hot oil on it. I'm also working on a new intake filter. The PO had one of those cone filters and personally, I don't trust them much. Besides, I think that's where most of the noise in the cab is coming from - the intake.
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Interesting take on vnt control.
http://forums.tdiclub.com/showthread.php?t=40167
Thanks b-bob, I've been watching that thread - very interesting. I'm a mechanical guy and while all the stepper motors, boards and code sound interesting, I just don't think along those lines. I'd like to try but not sure if my old brain is up to it ;D
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Interesting take on vnt control.
http://forums.tdiclub.com/showthread.php?t=40167
Thanks b-bob, I've been watching that thread - very interesting. I'm a mechanical guy and while all the stepper motors, boards and code sound interesting, I just don't think along those lines. I'd like to try but not sure if my old brain is up to it ;D
If you message him he will send you pictures of his device. He sent me some but asked me not to share them yet as he is trying to work out a deal with the company that makes what he based his design off of or something to that effect. It's nice much nicer than I expected.
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The thermostat doesn't affect the flow to or from the heater. It regulates the temperature of the coolant entering the engine. Once normal operating temperature is reached, heater output temperature is affected some by load but the effect of the thermostat is only inasmuch as the inlet temperature is kept constant.
The TDI club link is to a discussion of extended service warranties not VNT control.
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http://forums.tdiclub.com/showthread.php?t=401671 :-[
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The thermostat doesn't affect the flow to or from the heater. It regulates the temperature of the coolant entering the engine. Once normal operating temperature is reached, heater output temperature is affected some by load but the effect of the thermostat is only inasmuch as the inlet temperature is kept constant.
The TDI club link is to a discussion of extended service warranties not VNT control.
Thanks libby for another good bit of info and clear perspective.
As for the TDI club link, all It sends me to is a discussion on VNT's, and as I had mentioned them earlier, I thought that was the reason for the link. If there is some mention of service warranties, I am missing it somehow. Also missing the relevance, but there must be some ;)
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All sounds frightening to me.
Great photo of the back plate [I may nick it ;D ]
Now that the belt is off you have to put it all back on again, using whatever timing technique you did before.
Then if you do the check I explained earlier, you will know
(i) Does the fuel reach the injectors, and,
(ii) Is the timing basically correct, and probably only needs fine tuning, or is it all way off...
Re the recommended timing, there is nothing definitive, but your value of 0.95 seems quite high for a 1.9. I would try 0.90mm and then 0.85mm, and 0.80mm I don‘t expect you to end up with timing like mine, but you could as an experiment retard timing until engine stumbles, then advance just off it, note the timing and then advance until the engine falters. Again note the timing, and consider bisecting...
Just to clarify re the thermostat operation:
I never said that it varied the flow rate to the heater. I did suggest that the stat‘s hysteresis allowed it to variably control the flow through the radiator, to control the engine temperature which indirectly regulated the heater and that had it operated as a switch, the heater would fluctuate more.
If the 180 you refer to is 180deg F then that is 30 degrees F below boiling point of water. Therefore you are better running pure ionised water in your system as it is actually more efficient at transferring heat.
Many engines including VW’s run above 212F. Hence the provision of the cap with a pressure release of about 17 to 19psi...
Interesting points that come to mind are:
Does the Quantum warm up to operating temperature quicker than the Golf etc, because one can shut off the flow of water to the heater with the valve, except for a little pilot flow.
If the radiators are sized, well within their limits for correct operation of the vehicles, why is it neccessary to have such a larger radiator when a/c is fitted?
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There is virtually no hysteresis with a properly functioning thermostat. This can be readily observed with the data-logging features of the AHU/1Z TDIs that use the same cooling system. The 'hysteresis' you describe is the classic symptom of a sticky thermostat.
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If the radiators are sized, well within their limits for correct operation of the vehicles, why is it neccessary to have such a larger radiator when a/c is fitted?
Not only does the AC dump heat in front of the radiator (in the hottest of possible weather), it also adds 15% extra work to be done(if you drive with the windows up anyway)....but lots of cars use the same part AC or no.
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The vanagon radiator is over-sized regardless of A/C. Same radiator was fitted for A/C or non-A/C equipped vanagons.
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Budget and packaging not withstanding, one can never have too much thermostatically controlled cooling. (or be too thin or too rich).
I can't speak as to the Vanagon, but a Rabbit TD'd with AC on when working hard is pushing it cooling wise on the stock system.
Hence the relatively giant radiators on real hard-work vehicles like 745 mentioned, and the availability of "tropical climate" clutch fans
on many vehicles that use such, and various thermostat temperatures.
A truly go anywhere anytime cooling system will by nature be overkill for 90% of people 90% of the time.
That 10% bugs me personally and I operate with an eye toward it.
When you get the Vanagon cooling and sorted out, put an oil temp gauge in it for more fun and worry/expense.
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Some funny stuff it there ;D
I do have an oil temp sensor and gauge but I'm not paying attention to it cause I need to swap the + - wires to get a proper reading. It has a 180 F switch on the cooling system though and I have heard the aux fan come on a time or two.
I'm much closer to the my goal but your right, it's that last 10% that's bugging me. This van/project is a concept that is supposed to bring endless joy and minimal sorrow at the drop of a hat, under extreme conditions. My patience is (or lack of) is allowing compromise creep in. On the other hand, spending every weekend "working on the van" is getting old, especially for my sweetheart.
There is after all, another life (I think).
Finish the air cleaner build, and mess with the timing light and timing - one, two days max, done.
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Funny, I had to cut and reverse the wires on my VDO trans temp gauge because it's wired backward from the VDO oil temp gauge I got the connector from.
I subsequently repined the connector so my colors were back to right.
Make a pump-bracket mark, light time, rotate your pump in 1mm increments till you find the spot you like, then check time again will cut some hassle time.
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Keep at it, if it was easy everyone would do it. :)
I found a stout engine oil cooler to be of benefit on a hard working TD, and pleasant overkill on a NA motor.
Easier said than done on a Vanagon I guess, but it's a thought.
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I'm much closer to the my goal but your right, it's that last 10% that's bugging me. This van/project is a concept that is supposed to bring endless joy and minimal sorrow at the drop of a hat, under extreme conditions. My patience is (or lack of) is allowing compromise creep in. On the other hand, spending every weekend "working on the van" is getting old, especially for my sweetheart.
There is after all, another life (I think).
Finish the air cleaner build, and mess with the timing light and timing - one, two days max, done.
I can feel your frustration\pain - as I've been there many times with diff. projects (putting a steel roof on my multi angled roof house by myself - 2wks straight turned into 4 wks ???)
But seems that you are just about there & it is a new year!! A bit more finetuning and you'll have a super rig to drive in.
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I do have a good oil cooler and remote filter mounted. Fan turns on at 180 F. I've heard it several times.
Good idea on the timing marks before I move it. Right now it starts easy - almost too easy. I'm hoping to quiet the intake with something I will fab up today. I think a lot of the noise in the cab can be attributed to it, but that's way off topic. Messing with the IP timing may reduce my EGT's a bit as Mark and several others have pointed out.
Thanks all - Happy New Year
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Speaking of your intake, where is the filter located? I tried the best I could to isolate mine from engine heat. I built a lexan shield over the filter so that it would take more of the cold air rather than the engine air. That could be part of your issue is pulling hot air once the thing warms up.
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Speaking of your intake, where is the filter located? I tried the best I could to isolate mine from engine heat. I built a lexan shield over the filter so that it would take more of the cold air rather than the engine air. That could be part of your issue is pulling hot air once the thing warms up.
The intake used to be a K&N filter (don't like them personally) located at the end of some ABS fittings and stuffed into the driver's side pillar (the inside corner of the van where outside air is supposedly directed into the bay at speed ( now that sounds funny). I may block that off so the engine heat doesn't get to it as you suggest. It will also limit the air from cooling the bay though.
Right now I have a huge round filter but I'm thinking of starting over with a rectangular one from the local FLAPS and building a metal housing for it. Trying to reduce noise is the goal here and I doubt the round one is going to help that much.