LaughaC

Outside temperature dropped to 40' today and my engine never warmed up beyond 135' or so after an hour of driving. What should I do?

JackOlsen

Check your internal thermostat. It might be stuck open, which would keep the oil feeding through the engine-mounted cooler all the time.

If it's okay, and your car also has an external oil cooler in the front passenger side fender, check the second thermostat in the rear passenger wheel well. If the second one is stuck open, you'll feel warmth in the oil lines that lead to the front of the car before the engine temp has gotten up to 180.

theiceman

Hey jack how can you tell 180 degrees

does it correspond to one of the hash marks on the gage ?

ron mcatee

You'll know it's 180 degrees when you touch it. It will be hotter than hell and almost burn you.

LaughaC

Thanks. Yes, I have an external oil cooler in the rf wheel well and can check the thermostat in the rr wheel well.

How and where would I check the internal thermostat? I have not found an engine-mounted thermostsat on the car.

Peter Zimmermann

ice: With a small flashlight in hand, lean close to your oil temp gauge. Direct the light beam sideways and under (through the glass pointing the flashlight to your left) the gauge bezel. Place yourself so you can look behind the bezel and you will see tiny, white numbers, which are Centigrade readings for your oil temp.
Pete

Mike Murphy

Please tell me if I'm looking at this correctly - My '88 Carrera appears to have a stuck-open thermostat. When driving in cold temperatures (35F or less), the car warms up to about the middle between the 1st and 2nd white lines (first line is 140F and second line is 194 degrees F). The problem is, how do I know which thermostat is stuck-open? At 176F, the internal thermostat opens up. At 181F, the external thermostat opens. So it could really be either thermostat at this point. I assume I should feel the oil cooler line by the right front fender to see if they are warm? Is this an accurate way to test? Finally, if it is the external thermostat, should I rebuild the one I have or just buy a new one? They run about $300 on Pelican...

Is there any problem with running the car this cold? If Porsche set the internal thermostat to 176, and you wanted to drive the car in extremely cold weather, your car might not ever get above 176 if it's cold enough. That still seems a little cold to me, right?

Mike Murphy

Oh, I forgot to mention - when I park the car and let the engine idle, the temperature starts to climb. Then when I drive off at highway speeds, the temperature start dropping again...

DBrisson

Is there really something as to cold on an air cooled car? sure your oil temp is down but I have to guess the head temps are good or else it would be running poorly.

Mike Murphy

I think I answered my own question. I found Bruce Anderson's oil temp chart. I think "too cold" may be a problem with condensate not evaporating off properly, and anything below 180 looks to be "too cold." I wish Bruce said something about "too cold" and "too damn cold."

glenncof

murphy,

Did you reconcile this issue concerning cold operation ?

I had mine out today in San Fran area, low 40's and never got above mid-point of two lower marks (~75C) on 20miles of highway. It's really slow to get there also.

I could pull thermostat and test it but don't have spec.

Did you resolve ?

LaughaC

My guess is that my internal thermostat is stuck open. Any advice short of ordering a rebuild kit for it?

Am I apt to ruin the gasket by pulling it apart to take a look at it?

ron mcatee

The internal thermostat is on top of the engine, just to the right of center. If you remove it, make sure you put a new "O" ring on the new thermostat. Oil causes the rubber goods to swell a little and heat causes them to compress. That will ensure you don't have a leak. Also make sure you lubricate the "O" ring so it glides into the engine cavity. If not lubricated, You risk possible "cutting or shaving" of the "O" ring and will almost always develop a leak since that cut or shave part of the "O ring will be a weak point on the seal. I always buy two in case I mess one up. If I don't need it I take the unused one back or keep it as a spare.

Jay H

This post is more for the archives since I bet Murphy's got this issue long resolved. My trusted mechanic replaced the 'plunger' portion of the external thermostat as a precautionary measure when I had a hard oil line replaced. The plunger cost ~$85 from my dealer and probably didn't take all that much labor to replace. Replacing the entire housing isn't necessary.

BMWDavid

You know my oil temp is about the same during 25*-35* driving. Regarding the internal thermostat...is it removable without much work?

What is involved doing the work?

David