High temperature while driving in City traffic

[Juan911]

Hi all, when I drive my 1991 964 in traffic and it sits idle, after about 20 minutes the temperature needle goes very high and a burnt smell creeps into the cabin of the car. Once I hit the freeway and start going the temperature reading goes back down to below the midle line. Is this normal or is there something malfunctioning? I have heard mixed comments so I really would like to know and I don't overheat my car while driving on the City. It has never reached the red but it has gotten very closed. My car has 80k miles and everything is original on it. Does anybody know where i can get a maintenance book so I know what parts I need to replace or what preventive maintenance I can do to my car at 80K?

Thanks in advance.

[Bill Verburg]

Originally Posted by Juan911

Hi all, when I drive my 1991 964 in traffic and it sits idle, after about 20 minutes the temperature needle goes very high and a burnt smell creeps into the cabin of the car. Once I hit the freeway and start going the temperature reading goes back down to below the midle line. Is this normal or is there something malfunctioning? I have heard mixed comments so I really would like to know and I don't overheat my car while driving on the City. It has never reached the red but it has gotten very closed. My car has 80k miles and everything is original on it. Does anybody know where i can get a maintenance book so I know what parts I need to replace or what preventive maintenance I can do to my car at 80K?

Thanks in advance.

Sounds like the oil cooling fan isn't working at all or maybe only works on low speed.

There are several possible causes, most likely the fan itself but also the fan resister is a known weak link.

It's fairly easy to change these parts out if you are mechanically inclined, otherwise take it to a reputable shop.

[911Urge]

Spend some time reading this.

964/993 Oil Cooler Fan Operation & Troubleshooting

[Juan911]

Thank you, after lightly reading some parts of it, it seems like that is my issue. I will check what is recommended and let you know. Yes my car is usually much higher when sitting in traffic and apparently is not normal. I'll try a couple of things to see what works best. Thanks in advance.

[Juan911]

Hi all I have to revive this post since for some reason my mechanic has not found the culprit to the running hot issue. We have replaced the A/C control unit ($750 dollars rebuilt) I have also replaced the thermostat, he check the fan funtionality and he said it was working fine. So after more than 2K the car still gets very hot in city driving and the needle never goes down below the most highest (10 o'clock marker). This is kind of frustrating because he now wants me to replace the thermostat housing and the hoses that go along with the new housing, he hasn't giving me a price but knowing him he will probably ask me for another 700 or 1K dollars. I had to fight him to replace the thermostat for a lower fee since it was part of the initial issue that he still hasn't fixed. I don't like confrontation but I think I should have to pay any more money for labor since his first quote stated that it was going to be fixed. With both times back to the shop it has cost me about 2.5K and the problem still persist. Any help and advice will be greatly appreciated. Thanks

[86 911 Targa]

Originally Posted by Juan911

Hi all I have to revive this post since for some reason my mechanic has not found the culprit to the running hot issue. We have replaced the A/C control unit ($750 dollars rebuilt) I have also replaced the thermostat, he check the fan funtionality and he said it was working fine. So after more than 2K the car still gets very hot in city driving and the needle never goes down below the most highest (10 o'clock marker). This is kind of frustrating because he now wants me to replace the thermostat housing and the hoses that go along with the new housing, he hasn't giving me a price but knowing him he will probably ask me for another 700 or 1K dollars. I had to fight him to replace the thermostat for a lower fee since it was part of the initial issue that he still hasn't fixed. I don't like confrontation but I think I should have to pay any more money for labor since his first quote stated that it was going to be fixed. With both times back to the shop it has cost me about 2.5K and the problem still persist. Any help and advice will be greatly appreciated. Thanks

It would appear that you are not getting a "fair" deal on this issue.

I'm not at all familiar with the 964 model year,
but these "ongoing" repairs do not appear to be justified.

My thoughts are, move on to a new mechanic.

Something is just not right.

Good luck,

Gerry

[computamedic]

I think you can do a few diagnostic checks yourself to help clarify the problem.

Firstly, when you drive from cold, check the action of the oil temperature gauge. It would normally rise quite slowly as the engine warms up - probably over a 10 minute period of driving. When the temperature gauge reaches to around the first graduation mark you SHOULD notice that there is a sharp drop to, perhaps, half that level. That sharp drop is coincident with the oil thermostat opening.

I have found that in normal everyday driving the oil temperature rarely rises much above that level. However, with either some spirited driving or standing in traffic the oil temperature can very easily rise considerably. After all, the engine is partly cooled by air flowing over the barrels and when standing still the engine cooling is dependent on the air driven from the main cooling fan and the cooling of the oil in the oil cooler.

The fan on the oil cooler should normally come on at low speed once the oil temperature starts to rise much above the first mark. The high speed will only be selected if the temperature continues to rise to a much higher level. This will rarely happen in normal driving but it IS possible if standing still for an extended time.

If the oil cooler fan checks out OK it remains to be seen if the oil is reaching the cooler. A hand on the front right fender should tell you if it's hot to the touch.

Hope that helps.

Regards

Dave

[bazar01]

Originally Posted by Juan911

Hi all I have to revive this post since for some reason my mechanic has not found the culprit to the running hot issue. We have replaced the A/C control unit ($750 dollars rebuilt) I have also replaced the thermostat, he check the fan funtionality and he said it was working fine. So after more than 2K the car still gets very hot in city driving and the needle never goes down below the most highest (10 o'clock marker). This is kind of frustrating because he now wants me to replace the thermostat housing and the hoses that go along with the new housing, he hasn't giving me a price but knowing him he will probably ask me for another 700 or 1K dollars. I had to fight him to replace the thermostat for a lower fee since it was part of the initial issue that he still hasn't fixed. I don't like confrontation but I think I should have to pay any more money for labor since his first quote stated that it was going to be fixed. With both times back to the shop it has cost me about 2.5K and the problem still persist. Any help and advice will be greatly appreciated. Thanks

Are you comfortable with a digital meter and do you have one? It will save you lots of mulah if you do. $2.5k could have gone to some good upgrades if you can do some simple tests.

This is a similar issue you can read.
http://forums.pelicanparts.com/porsche-964-993-technical-forum/524323-95-993-condenser-oil-fan-issues.html

[Juan911]

HI computamedic, yes i've been very observant regarding the rising of the temperature. I think the Thermostat is not operating correctly since there is no drop in temperature at all when sitting iddle or driving in city traffic. Yes when i open it up in the freeway the temp does come down a bit but not as much as to what is recommended with some of the other posts and a great doc I received from one of the fellow pelicans.

I also think it has something to do with the mechanic just like 86 911 Targa said. He is kind of shady but again, it's been very dificult to find an honest mechanic.

I don't know much about the works ins and outs fo my car but I'm sure learning and I would like to learn more, but it looks like it's been very expesive so far for something that still hasn't been fixed.

So to go back to the original issue; the marker just keeps rising without a break. I've seen how the temp goes up and then it comes down in other cars but my car does not do that. Again, my mechanic has already made me replaced the A/C control unit (750 dollars rebuilt) the thermostat and now he wants me to replace the housing and some hoses which by the way he said are not cheap.

Thanks all for your great input, I'll see how things go when I bring my car back to my mechanic and ask him to look into what he's done so far and make sure he gets it working.

[cjoenck]

It is possible your thermostat does not open, i.e. you don't get oil flow through the oil cooler. That would explain why the fan does not come on. It is easy to check if the thermostat works. Your right front fender of the car should get warm to the touch when your engine is hot. If you do not feel a significant temperature difference between the right and left side, I would bet money your thermostat does not open.

Basically repeating the comment from computamedic above for emphasis - because it is so easy to test.

You can easily check the temperature sensor. Remove the wires from the sensor and attach a variable resistor to the wire. Simulate the temperature sensor by gently decreasing resistance and you should see the fan operating in both low and high speed. You can buy a variable resistor for a couple of bucks at Radio Shack.