AAZ overheat?

[Gizmoman]

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.

[92EcoDiesel Jetta]

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.

[92EcoDiesel Jetta]

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.

[libbydiesel]

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. 

[wolf_walker]

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.

[Gizmoman]

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   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.

[theman53]

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?

[the caveman]

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

[the caveman]

oh yeah, you will need to rebleed it again if you haven't already

[Gizmoman]

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

[wolf_walker]

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.

[Gizmoman]

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.

Looks like a cast impeller

Here's the previous pump - nothing wrong with it, just wanted a new one for the "new" engine.


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?

[the caveman]

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.

[745 turbogreasel]

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.

[Gizmoman]

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.