Temperature too low

Car is running OK, but the temperature gage reads about 70C deg (158F), which has been confirmed with ScanGauge II. I have removed the bottom cover (skid plate - damaged) and disabled EGR cycle. During summer the temperature will reach normal temperature. Is there 'too much' cooling because of so much draft through the engine compartment in winter months and is the engine going to be affected in any way, long term? Is there perhaps different thermostat that would be able to compensate for this? It takes forever to get any significant heat to passenger compartment when the outside temperature is bellow 0C deg.

Consider a winter front. It's available from VW.

I don't know. If the dash and Scan guage temperatures agree, and the cabin is not getting heat, that points away from the Coolant Temperature Sensor as the culprit, even though they're notorius for failing. I read that the thermostat is designed to fail in the open position, which would result in a cooler engine, but that wouldn't explain how your temperature is normal in the summer. Unless this only started happening this winter. Problem is, VW thermostats are supposed to be pretty reliable.

Ontario+diesel+cold temperature=hard to get hot vw tdi. Do what DD suggested, or search for the mod on the pipe insulation mod to restrict air movement into the radiator.

I'm not going to say it's not the thermostat, but sticking a piece of cardboard or whatever to block the air flow is a quick and easy check.

Are the thermostats in these cars problematic?

I've got 190,000 miles on my thermostat...

never had to replace one... however I've heard you need three peices, the thermostat, the housing, and the o ring otherwise it'll leak.

You didn't say where in Ontario, but it gets as cold here as anywhere south of James Bay and I have never had low engine temperature due to low ambient temperature and never blocked off the rad. I also have not removed my bottom plate, and if you would rather not buy a new oil pan, consider replacing yours. I doubt that losses from the block are a factor. I am with the "failed thermostat" camp. It happens, and they all fail open. Some aftermarket ones fail after a single overtemperature incident.

alphaseinor said:

I've got 190,000 miles on my thermostat...

never had to replace one... however I've heard you need three peices, the thermostat, the housing, and the o ring otherwise it'll leak.

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I replaced mine a few weeks ago because my car took forever to heat up. You do not need to replace the housing, but you will likely break the 2 pins that hold the thermostat in place because the thermostat will be stuck to the engine. If they break off, putting the thermostat back in will be very hard and annoying but it is doable. You will also need the o ring seal.

My car warms up within 5km of me leaving my house now.

SilveR316 said:

My car warms up within 5km of me leaving my house now.

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Is that better or worse than before

I just replaced the thermostat and if you twist the housing clockwise first (it wont twist much) and wiggle it a bit you can get it out without breaking off the fingers. They are only there to hold the thermostat and )-Ring in place as you insert it back into the engine. Having said that I ordered a new housing for $5.95 just in case but did not need to use it. You will need to order some G12 too as you loose some during this work. I found that the 1.5 Litre bottle was enough for me.

Thank you for all the responses. I live in the Southern part (close to Windsor). I noticed this condition since the delation of EGR and other mods (see the signature). This is the second winter having this issue. Better cold than overheating. After all, when you are using only 4.5L/100km there is not much left to heat the cabin. I may just try a new thermostat.

I've seen a thermostat fail. Had to replace the one in my dad's 96 Passat TDI. It failed in the open position, and the symptoms were as follows:

- low reading on temp gauge
- very little cabin heat, even after 30 minutes.
- if you drove it onto the highway, the temp gauge would read even lower and you got zero cabin heat.

Replacing the tstat solved it. If it's *really* cold out, you might experience similar symptoms even though everything's working just fine. I had that happen one winter driving through Vermont. I came up with a make-shift winter front using split foam pipe insulation and zip ties to completely block the upper and lower grille. I had nice heat after that.

I suspect that your primary issue is the thermostat.

While your messing with this, I would definitely replace the lower engine cover. Even in Kansas I had lost mine at the end of winter from some heavy snow. I went into the summer with it off and did not notice any real difference. Once I got into the colder weather again I noticed it being slower to heat up and also seemed to take a significant hit on my mileage. The mpgs came back up when I installed a new bottom engine cover.

While ordering a new thermostat I noticed that they had three different temprature designation, 70C, 80C and 90C. Since mine seems to stay at 70C (according to ScanGauge) I will try the 90C and see what hapends. It was less than $7.00 at RockAuto.com. As far as engine cover goes I am sure that it doesn't help not having it in place, but I got tired of taking it on-off (frequent oil changes) and torn side covers don't help to keep it in proper place (went through deep snow once). I think all the troubles started with missing screws and clips after few oil changes done by the 'profesionals' of VW of A.

dieseldorf said:

Consider a winter front. It's available from VW.

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Just a quick FYI, they're not available thru VW anymore. Numbers aren't even in their computers...at least not in WI or northern IL. Haven't checked for myself yet, but, I'm told Impex has 'em.

Wolf, if you do find 'em, lemme know...I need one