Heater Problem

WAKeele

Veteran Member
Joined
Jan 2, 2008
Location
Missoula, Montana
TDI
2002 Jetta GLS
Well two days ago while just starting to leave Chicago on the Dan Ryan to drive back home to Tennessee, I noticed my tempature gauge was reading about 230ish shortly after the 94/57 split (I was averaging about 80mph). It always sits at 190 after warming up (keep in mind I've only owned a Jetta TDI for less than a month).

Since I wasn't in a good place to investigate it futher, I turned the heat up all the way to try to get the temp down a little, while slowing down to about 65mph. It got hot in the car quite fast (the wind chill about that time was -25 F) so I had to crack the windows to keep from overheating myself.

So after a few minutes it temp started dropping slowly. I was going to stop for fuel once I got into Indiana anyways, so once I crossed the border I started looking for stations. During this time, the temp dropped about 10 degrees to 190 pretty quickly but steady once it got to 190. While headed down the offramp, the temp starts dropping rapidly as a slow. So within about a minute and a half it goes all the way to starting temp.

After pulling up to a pump and popping the hood, I let it idle for about a minute or two. After getting out and checking the engine, I notice the engine is pretty cool and didn't show any signs of overheating. I pumped fuel and such then went back to take a closer look. The coolant level was fine.

So I headed back on the road. The temp started going up again as I pulled away from the station (to the third tick in the cool zone) but by after about 100 meters, it starts going back down.

Now back on the interstate (with no temp reading) I notice it's not warming up at all in the car. I had the heat all the way up and it was just luke warm.

I'm guessing it's a thermostat problem due to the around zone temps in Chicago the nights before. The antifreeze ratio wasn't mixed for weather below 20F by what the previous owner said, so I added more when the weather got colder when I was in Cincinnati before Chicago.

So for the rest of trip, it stayed all the way down with mildly warm air. A similar instance has happened with a 92 Jeep Cherokee and it was the thermostat.

Tomorrow I start going through the books and tinkering with it. Any suggestions or advice?

It's a 2001 Jetta TDI manual with 186.000 miles.

Thanks!
--Adam

On a side note, I'm looking for a skid plate, front ground spoiler, front door lights, a new or rebuilt EGR (mine started spitting oil) and a set of 15" alloy wheels if anyone is trying to get rid of any.
 
Last edited:

lost1wing

Veteran Member
Joined
Jan 23, 2007
Location
USA, Georgia, Homerville
TDI
2003, 2003, 2002, 2000 ,2000
Looks like the thermostat was stuck closed at first, then opened and remained open. That is why the car wouldn't warm up completly when you got it back on the road. That is a good place to start anyway, replacing the thermostat.
 

mrGutWrench

Top Post Dawg
Joined
Aug 29, 2002
Location
Wallace, NC
TDI
'03 Jetta Wagon
lost1wing said:
Looks like the thermostat was stuck closed at first, then opened and remained open. That is why the car wouldn't warm up completly when you got it back on the road. That is a good place to start anyway, replacing the thermostat.
__. Whatever, these are screwy symptoms. I was thinking:

1) Maybe the guage is just acting up, or,

2) It's the thermostat.

__. If there's a real problem, I agree with Wing that it's probably the thermostat. (The only other thing I can think of is a head gasket problem and we *really* don't want that!)
 

WAKeele

Veteran Member
Joined
Jan 2, 2008
Location
Missoula, Montana
TDI
2002 Jetta GLS
Thanks guys!

I removed the thermostat and have it a look over. I asked the guy I just bought it from and he said he had just replaced it not long ago with one with a fail-safe. That explains it remaining in the open position. I couldn't find any reason it wouldn't work properly mechanically and reinstalled it. No problems in almost two weeks.

I'm guessing the significantly colder temps in Chicago (no warmer than 10F and -25F windchill while I was there) over TN or Houston (where it came from). Also, I don't think I mentioned that day after sitting all night in the cold, I didn't let the car warm up as usual before driving off. I was in a rush to get a friend to the airport. So I figure something with that caused it to stick in the closed position and the outside temp keep the engine heat down until I started driving hard leaving the city.
 

Lex4TDI4Life

Top Post Dawg
Joined
Jun 22, 2006
Location
Stamford, CT
TDI
2001 Golf-Ute TDI GLS 5spd Manual
WAKeele said:
Also, I don't think I mentioned that day after sitting all night in the cold, I didn't let the car warm up as usual before driving off.
You generally shouldn't let the car idle to warm up. Not only is it ineffective due to the thermal efficiency of the engine, it allows for oil to leak past the turbo seals. Too much of that and you get oil feeding your engine - not cool.

In any weather, I start her up, wait maybe 10 seconds for idle to even out and oil to get flowing, and then I start driving.
 
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