Using exhaust for heat?

[Juanito84]

My 1985 Golf diesel is worse than my 1971 Bug when it comes to heating. If I'm going down the highway it's ok. But for around town it isn't. I have a 1,600W circulating engine heater I use before driving. That will make the temp gauge move in about 1 to 2 hours, depending on ambient temperatures. Then I get in and drive. If I leave the heater alone the temp gauge continues to climb. If I turn on the heater the temp gauge drops and within a few minutes it's blowing cold air, and if it's -30° F or colder the air only comes out warm not hot even when the engine is within running temperatures, although soon the engine temperature drops. Usually the defrost doesn't do a thing because I cannot get enough heat for long enough.

Yes, I have a working thermostat. Yes, I block off most the radiator with cardboard. The only thing cooling down the engine coolant is the cabin heater.

I was thinking of using the exhaut to heat the water some how. Maybe I could implement a newer TDI EGR cooler to do the trick? Any ideas?
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

[ps2375]

Sounds like your thermostat is a cold one or is stuck at some point. My gasser Rabbit could cook me out of the car sitting still, in town or on the highway.

[Juanito84]

I'm sure the thermostat is fine. I've tested it and it is the OE specified temp too.

There's a big difference between gasoline and diesel engines when it comes to heat. For putting around town a diesel passes a lot more air through because they don't have a throttle to restrict it so they therefore burn much cooler. Idling hardly warms them because of all the cold air passing into the intake. Also being that diesels are more efficient they turn more fuel into power and less of it into heat. I can get 50mpg on the highway and not too bad in town either out of this engine on diesel fuel which has less energy than gasoline! Then add -30° F bellow to the equation and heat becomes impossible to produce.

Sure, out on the highway and the engine heats up to running temperatures. But for in town it doesn't unless I don't use my heater.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

[stewardc]

Well, it certainly sounds like you have a problem. I'll admit that my Caddy has a smaller cabin, but the heater is fabulous at all times....and remember that I live in the land of COLD, Canada. Check the thermostat, heater valve, flush out the heater core and check for debris in the fan.

[Old n' slow]

I had the same problem in two 1981 Rabbit diesels that I drove for 10 years . With everything working properly (thermostats , water pumps) I would freeze inside when the temperatures were in the single digits and I was driving at 55mph . My current 1991 doesn't seem to be as bad . Maybe the heater cores are bigger or maybe it's because I don't get up at 4 am in the winter and drive 75 miles (one way ) on the highway to work

I wish I knew a way to get more heat using the exhaust .
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Currently own : 1969 Beetle w/ 1600cc, Single Port, Solex 30 PICT 2, Dist. 113 905 205 T, stock exhaust.
All my daily drivers gone but not forgotten;

1964(sunroof)1967 & (2)1968 Beetles , 1968 Squareback , 1963 (23 window )Deluxe Sunroof Bus , 1969 Westphalia camper, 1974 Dasher , 1985 Vanagon , (2) 1981 Rabbit Diesels & a 1991 Jetta Diesel .

[Juanito84]

Well I know it's not the heater core, because if the engine is warm then heat comes out. But as I drive the temp gauge drops and so does heat.

Newer diesels have a few advantages that warm them up better. For one, they are a larger displacement and more powerful. It seems to me that that would give the engine more surface area to assorb heat out of the combustion gasses as well as having the abillity to create more combustion gasses. And second, the fact newer ones have EGR systems that cool the EGR gasses with engine coolant, therefore heating up the coolant. And third, newer vehicles tend to weigh more meaning the engine has to do more work to get the car moving down the road. Add all the accesories, like power steering, that the engine now has to drive and that also requires more power and means more heat.

In mine I get heat going down the highway. It's in town where the problem is.
_________________
If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

[ps2375]

I described this to a fellow dubber, he said could also be the waterpump. You might want to check the impellor.

[Juanito84]

[ps2375]

It not motor temp, it's water flow thru heater core.

[ps2375]

[bvolks]

I drove a 1985 Diesel Jetta for 12 years and never had any problems with it not producing enough heat, and it gets quite cold here in the winter.
Your problem sounds sounds exactly like when I had a bad thermostat in my '89 GLI.
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1985 Diesel Jetta Coupe (temporarily retired at
756,000 km)
1971 Doublecab project
1995 Golf CL
1974 Beetle
1978 Westfalia

[Juanito84]

The problem only appears when it's well below zero and I drive around town at 25mph or less and have the heater on full blast, which right now is all it does because the resistor board is bad.

I havent actually taken out the thermostat recently but I have tested it in the past and from what I can tell it's still working fine.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

[ps2375]

So, you don't actually know if the thermostat is still good or not. Go buy a new one and give it a go, then you'll at least know it's good.

[Juanito84]

That's what I did last winter. And the new thermostat didn't make a difference. I'd rather put it in a pan of water with a thermometer and see if it's opening at the right temp. Usually just taking it out will show you if it's stuck open or not.

If I do get another one I'm tempted to put in a hotter thermostat. Any reason not to?
_________________
If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

[ps2375]

[Juanito84]

Let me explain the history of this car.

When I first bought it it had a colder thermostat, the coldest one available (72°C 161°F). I think the PO did that to make up for the fan not working, which I fixed. The temp gauge would normallyjust move a little; summer, winter, it didn't matter. Except when I turned on the heater full blast at below zero temps around town. Heat would come out, but the gauge would soon drop the little bit it could and not long after the air would come out colder and colder.

Well I took the thermostat out and tested it last winter. It worked fine for it's temp rating, but I bought an original temp thermostat (87°C 189°F) to see if that would help. Well now the temp gauge normally rests right in the middle. Except when I turn the heater on full blast around town during below freezing weather, it does the same thing that it did with the last thermostat. The temp gauge drops and it blows colder and colder.

Now to me this is normal. I've driven plently of vehicles of all shapes and sizes that do the same thing. It gets to -40°F (-40°C) around here. My Golf only does it around town, at speeds of 25mph or less. At higher speeds the engine keeps up with the heat and the temp gauge stays up. Mind you, my Golf doesn't have a way to heat recirculated air. So if it's -20°F, -30°F or -40°F, that's the temp the air is that is blowing through the heater core. Can a 1.6L diesel engine burn enough fuel between idle and 25mph to heat -40°F air up warm enough to heat the interior of the car? I know lots of people who have the same problem I do.

Now I might try a hotter thermostat. But I do feel that even if I blocked the water passage to the radiator completely it would still do the same thing. If it does then using exhaust heat would probably be my best bet to heating the interior of the car. Either that or an auxiliary heater that burns diesel to heat the water. Or maybe fabricating a recirculating duct over the heater core.
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If a water cooled engine cools its water with air, isn't it just an overcomplicated air cooled engine?

[ps2375]

I have never dealt with a Diesel car and I don't know that I've ever puttered around that slow in temps that cold, so I'll leave it others that have.

[HeidelbergJohn4.0]

Are you sure you are getting good flow through/to the heater core? if you don't have an air recirculation option, sounds like you are trying to heat cold air with cold water.
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71 LWB Manx style dunebuggy
71 Beetle
71 Volksrod
Machette Speedster
2012 Passat TDI SE (sadly sitting in a buyback parking lot somewhere waiting for it's heart to be ripped out.)

[Juanito84]

[HeidelbergJohn4.0]

there's always

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71 LWB Manx style dunebuggy
71 Beetle
71 Volksrod
Machette Speedster
2012 Passat TDI SE (sadly sitting in a buyback parking lot somewhere waiting for it's heart to be ripped out.)