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General Information => Troubleshooting => Topic started by: rabbitman on January 18, 2012, 07:55:41 pm
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So I've never had a good heater in the rabbit, it'll blow "warm" all winter but never HOT except in summer. Lots of new t-stats, 3 new heater cores and numerous times of taking the heater box in and out trying to find ANY problem with it. The engine DOES get up to temp, verified several times using different methods.
Outside temp is -35F. If I start it and idle WITHOUT the heater fan on the engine will get fully up to temp within a half hour.
However, same outside temp and same idle time but if I turn the fan on LOW the engine will never get hot. Even driving it with the fan on low makes it hard to heat the engine up and if I idle it up to temp and then turn the fan on the engine will cool right down.
So the heater system IS removing lots of heat from the cooling system, but why is the air not hot?
Remember, this is MK1, there are no hot/cold air mixing flaps inside the heater box, it's all controlled by a valve in the heater hose.
Any takers?
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its gotta be sucking cold air from somewhere.. does your heatercore have the foam gaskets on the sides/bottom of it to keep the air from blowing around it?
how hot is your t-stat?
i recently put a 190* t-stat in my car, and the heater works MUCH better now..
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BECAUSE ITS F****** MINUS 35 DEGREES FAHRENHEIT!!!
;D Your cooling system is just ridiculously efficient, that is all. RIDICULOUSLY. so much so that the tiny radiator that is the heater core, has the ability to fully cool the motor.
At those temperatures, i really doubt the engine ever actually gets to the point that the thermostat opens.. unless you have a very low degree thermo in there. Which is why you can maintain steady higher temps with the coolant valve shut for the heater core.
As soon as you open the heater core valve it is allowing the now freezing cold cabin air to take the not so hot air from the coolant.
The air is likely not hot because your body is too damn numb to tell the difference.. ;)
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Are your side vents fully closed? Those never get hot air. That foam around the heater core is also very, very important.
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What happens if you completely cover up the radiator. You can always keep an eye on the temp gauge just in case. You know how you see the semi's have those custom covers oner their radiators. Then letting more air pass thru till it's right on the temp gauge.
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Are your side vents fully closed? Those never get hot air. That foam around the heater core is also very, very important.
x2 on the side vents.. they are just straight outside air..
forgot about them for a sec, thanks for the reminder Tyler!
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What happens if you completely cover up the radiator. You can always keep an eye on the temp gauge just in case. You know how you see the semi's have those custom covers oner their radiators. Then letting more air pass thru till it's right on the temp gauge.
It wont matter to the coolant unless the thermostat has opened. However at cruising speed it will help cold air from blowing across the motor.
I love the cold air vents.. they are my favourite mk1 feature :)
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8V, you have me busting a gut here. Too numb to tell the difference? I'd say so.
Having a heater that doesn't crank the heat is so non-VW. I get heat out of the defroster within 3 blocks of the house after startup. At the temps you have going there I think the heater core is indeed working like the radiator. Do you block the radiator off in these kinds of temps. You should, cardboard, a vinyl flap, something, think like a trucker. On second thought, no don't do that, they are a nasty bunch. But do block the rad.
You say you have put in several t-stats. Temp ranges? I run the 190 degree one and that is hotter than the one that came in it a year or so ago.
I didn't see where you have checked the water pump for a free spinning or poorly functioning vane in there. Pumping that hot water into the core is kind of critical.
I must say getting a car running in that temp has to be an art. My sympathies. We had cold on the coast, 30F and even being bundled in coveralls I sissied out working on the timing as my hands wouldn't hold the wrenches anymore.
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What happens if you completely cover up the radiator. You can always keep an eye on the temp gauge just in case. You know how you see the semi's have those custom covers oner their radiators. Then letting more air pass thru till it's right on the temp gauge.
It wont matter to the coolant unless the thermostat has opened. However at cruising speed it will help cold air from blowing across the motor.
I love the cold air vents.. they are my favourite mk1 feature :)
all mk2 cars got them also, buddy..
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What happens if you completely cover up the radiator. You can always keep an eye on the temp gauge just in case. You know how you see the semi's have those custom covers oner their radiators. Then letting more air pass thru till it's right on the temp gauge.
It wont matter to the coolant unless the thermostat has opened. However at cruising speed it will help cold air from blowing across the motor.
I love the cold air vents.. they are my favourite mk1 feature :)
all mk2 cars got them also, buddy..
no they didn't? I have yet to see an mk2 that has the cold air vents.. yours were all A/C maybe that makes a difference? I have a 90 wolfsburg built jetta. Heat comes out of all the vents in the car. Window, feet, and passenger vents.
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Think like a trucker. +2
I think I'm running a 92C T-stat.
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Think like a trucker. +2
I think I'm running a 92C T-stat.
87c is 190*f
92c is 200*f
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How's your electrical system? My van would magically 'cool off' depending on electric load, such as fan motor, headlights, etc...
Chris
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That's why it reads 203-5 at the coolant coming out of the head. ;D
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That's why it reads 203-5 at the coolant coming out of the head. ;D
That is beauty for keeping a diesel warm in the winter.
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Is your coolant level a little low? That'll kill the heat.
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B_Y_M thanks for the reminder that mine is short in the reservoir and causes the gauge at the flange to read a bit low. How did you know?
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B_Y_M thanks for the reminder that mine is short in the reservoir and causes the gauge at the flange to read a bit low. How did you know?
after you log soo many miles in a mk1. you kinda have a mental connection to the car.. you know the cars every move, and whats right.. and any little change!
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Wow, thanks for all the replys!!
I do have the radiator almost completely blocked. But like 8V said, I don't think it helps other than to keep the cold air off the engine itself.
T-stat is "I think" a 195F. I just had a 87C in there and swapped it out for the slightly hotter one.
The cold air side vents are blocked off at the heater box, I never had the ducts to carry the air to the vents, I think the PO lost 'em.
Coolant level is good.
My electical system is ok, sometimes I see a difference in the gauge that I can't account for but it's usually short lived and then goes back to normal.
Water pump is for sure good. The skinny return hose is always squirting even at idle and then really hard revved up......haven't checked this pump with the screwdriver jamming method though.
-50F is not very nice to the poor car, I have all the engine heaters so it's actually easy to start but turning the steering wheel is difficult and if you thought the MK1 body rattled bad you should hear one that's really cold......no suspension at all. 8)
I also have an electric after run water pump off a '95 passat in the feed line to the heater core. It helps a lot at idle and a little bit revved up.
I've changed heater cores 3 times and have always really checked the foam seal around it and it's always been good. Last winter I installed a VEMO brand heater core and it was pretty good until this winter.
I flushed the system a year or two ago and it was clean.
I'll update as I think of more stuff.
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OK, so what do you think about removing the valve that controls the heat so you get max flow through the heater core. Should be easy and quick and lose hardly any coolant in the process.
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Honestly, I do not think that is the problem. Any of the gas mk1 vw's dont have any issue with heat. and they use the exact same valve.. its just that the motor is literally making no heat and it being that cold its probably struggling to maintain optimum combustion temperatures too.. lol
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I just finished changing out the blower motor on my 81. High speed was ok but the lower two were squealing to beat the band. Out did the music most times. What I noticed between the two heater cores I was working with is that they both had stuff piled up on them. I live around a lot of trees and all kinds of needles, leaves and stuff was coating part of my heater core. The blower motor was not really bound up, more of a wear issue at the bearing but it really couldn't force are down through the heater core to the rest of the plastic housing. I put in a motor from a car that had air conditioning and it really pushes the air now.
What are the chances that something is inside the blower motor squirrel cage? You should be able to see in there from outside the car under the rain tray. Anything plastered in there that would reduce air flow? Does it spin up good?
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B_Y_M thanks for the reminder that mine is short in the reservoir and causes the gauge at the flange to read a bit low. How did you know?
Because my mom's is low ;D
PM sent
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OK, so what do you think about removing the valve that controls the heat so you get max flow through the heater core. Should be easy and quick and lose hardly any coolant in the process.
I did that a few years ago and it didn't fix anything and then earlier this year I looked through the valve and it was totally clear so I didn't think it was worth leaving it out.
8V, my engine does get completely hot, it just takes a while.
ORcoaster, I had the heater core out a year ago so I doubt it would have blockage so soon, it also blows hard.
And to throw another wrench into it. I also have an auxilary heater with the coolant routed in series, first through the stock heater and then through the aux heater..........as soon as the temp needle starts to move the aux heater is blowing "heated" air, by the time the engine is up to temp the air is HOT. Yet the stock heater is only a little warm.
So in summary: The engine does get to operating temp, the stock heater does remove heat from the cooling system, the aux heater blows hot air, but the stock heater is somehow losing the heated air or getting cold air into the system.
I feel like I've overlooked something for the last 5 years and I'm dyin' to find what it is.......I really don't want to throw money at another heater core.......
The fact that the aux heater works so good really has me confused.
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your problems are INSIDE the box.. there isnt foam somewhere that foam needs to be..
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On the heater box I was working with this weekend there was a layer of foam at the joint where it connects to the hole in the rain tray, between the motor and the box and then there is foam all around all sides of the heater core. When I pulled the core out to check it for ability to hold water under pressure I noted foam on the sides of it, and it was totally mush. I could see that cold air could draft past the heater core as it is the path of least resistance. Foam also on the end where it goes into the box on the end opposite the hoses. If that foam was gone missing air would flow there as well. I am not sure the heat from the core can go any other place than out the bottom of the box.
I agree you need some foam somewhere.
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Maybe I have to look it over again.
A couple years ago I reached in the hole where the fan mounts and put duct tape around the outside of the heater core, it didn't help at all.
I also had some heater cores that I could shine a light in the inlet and see light in the outlet.........so that meant the coolant was allowed to shortcut and NOT go to the end and back. That was when I got the vemo core and it mostly fixed it for one winter.
Maybe a mouse got in there and chewed the foam out...........
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Wouldn't be the first time. I have heard tales or tails where nests were built on top of those cores and when the new owner turned on the heat they started smelling all that nasty stuff and couldn't figure out what it was.
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You said the cores are in serries, wich one is first? Have you tried them in parallel? Where is the aux core located in the car?
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You said the cores are in serries, wich one is first? Have you tried them in parallel? Where is the aux core located in the car?
The stock heater comes first so it can have the hottest coolant available going through it. I did try running them parallel and it didn't seem to be much different than series.
(http://i249.photobucket.com/albums/gg218/rabbitdude82/Rabbit015.jpg)
Wasn't too bad last night at -25F but this morning at -45F the air coming in was warmer than -45 but wasn't warm enough to be called heat.....
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Nifty heater my good sir.
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Nifty heater my good sir.
Thanks, I think it's probably saved my life a few times haha. Puts out some hot air, just not a lot of volume.
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Well we got us a heater heating a heater here or what? If I understand this setup you are removing heat through the stock core so you can keep the defroster and such working. Then if there is heat still left in the coolant you run it through a second core with a second fan behind it? Not sure I can tell from the picture. So heat from core #2 is dependent on residual heat from core # 1 and the amount of air being pushed through it.
At -45 degrees you are completely cooling your car with these two cores I am sure of it. If you have air blowing in through the engine bay, like most of us do and can't stop it, then you are getting all you are going to get. The only thing I think left for your setup is a very high temp thermostat. Or consider an electric accessory heater. Don't you have a monster battery in this or is that 8 V that does. Big battery equals inverter plus electric heater that is low enough watts to use without major mods to the electrical system.
Time to wrap the front end up like they do the big rigs. Underpan to keep air out.
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Me gots 1000 cca ;) But a measly 65a alternator.. Tdi swap will have 120amp booyeah. Its got coolant glow plugs right in the coolant neck feeding the heater core! :D
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Me gots 1000 cca ;) But a measly 65a alternator.. Tdi swap will have 120amp booyeah. Its got coolant glow plugs right in the coolant neck feeding the heater core! :D
that do basically nothing but waste power.. they dont even heat up the coolant faster.. there kinda a waste of time, or atleast thats the general concensus..
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ORcoaster, the aux heater comes second but blows WAAAAY notter air than the stock heater ever blows, I know it will seem hotter since it has interior air blowing through it but it starts heating before the stock heater ever dreams of making heat.
-60F this morning, bunny not happy. The interior never got above about -45F haha........
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ORcoaster, the aux heater comes second but blows WAAAAY notter air than the stock heater ever blows, I know it will seem hotter since it has interior air blowing through it but it starts heating before the stock heater ever dreams of making heat.
-60F this morning, bunny not happy. The interior never got above about -45F haha........
theres not enough air passing THRU your heater core.. its all going AROUND it..
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Maybe a daft suggestion, but could the blower motor be spinning the wrong way? kind of sucking the heat away rather than blowing air through the matrix? is that a possibility?
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Maybe a daft suggestion, but could the blower motor be spinning the wrong way? kind of sucking the heat away rather than blowing air through the matrix? is that a possibility?
you can spin a squirrel cage fan both directions, and it will still push air the same way. just pushes more spinning one way, than it does the other..
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I have air coming out the vents so no problems there.
I'll have to tear into this again, sometime.....maybe.....it's starting to feel like I've done it before......like at least 10 times.
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I'll have to tear into this again, sometime.....maybe.....it's starting to feel like I've done it before......like at least 10 times.
At anything below -25F you won't get much heat, period. As someone else said, it's too efficient an engine. We had the same problems with MKI and II's when I was a kid in eastern Canada. You learned not to breathe in the car so the windows wouldn't fog up :o
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That's massively cold. I'm willing to bet the engine doesn't get hot enough for you to even notice...
in -30c (-22f) my car blew cold air all the time so long as it was moving (and i know my t-stat isn't stuck open).
try letting it idle and get up to temp for at least 15-20 minutes then turn on your heat...
that's crazy cold...
What do you use for fuel at -60F?
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That's massively cold. I'm willing to bet the engine doesn't get hot enough for you to even notice...
in -30c (-22f) my car blew cold air all the time so long as it was moving (and i know my t-stat isn't stuck open).
try letting it idle and get up to temp for at least 15-20 minutes then turn on your heat...
that's crazy cold...
What do you use for fuel at -60F?
They winterize the fuel here, works good but if you have a car sit 'til winter with summer fuel you'll have issues for sure.
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ok, so, your aftermarket heater is pulling air from in the car and heating it right? your factory heater is pulling outside air and trying to heat it correct? I think that may be your problem? turn the factory heaters blower fan OFF, does the aftermarket heater get hotter? turb it back on, aftermarket cool down a little? with the tempt you are talking I wouldnt be supprized if there just isnt enough heat going through the core to compensate for the cool air its sucking from OUTSIDE.