911 SC Overheating and Stalling

[grovernk]

On an hour long shake out drive my 78 911 SC temp creeped right up to the bottom of the red on the temp gauge. I immediately pulled off the freeway and I noticed when I was downshifting that the rpms were dropping more than usual and it seemed like the idle wasnt catching, at the first stop I came to the car stalled. It took a few tries to get it started but i limped a few blocks home.

I had checked oil level halfway through the ride and it was ok

The car usually runs in the upper temp, but it has never crept to the bottom of the red

I just had a new alternator installed, could this have something to do with the stalling?

I was running the car pretty hard in 4th, could this have have it overheat?

What should I check?

[regency]

1st thing I'd do is check the fan belt, is it even there? Too tight / loose?

Steve

73 911 T MFI Coupe, Aubergine

[grovernk]

I'm a total newbie, so sorry if this is stupid, I have noticed since the alternator was replaced that the belt is squeaky, could this mean it is too tight?

[regency]

Well......thinking out loud, if there was no overheat problem before you had the alternator work done and now, it's overheating, then I'm thinking something's not right with the alt / belt. Now you're telling us the the belt is making noise. Why don't you get Wayne's Book 101 projects for your 911.

Hope you didn't hurt the engine.

Steve

73 911 T MFI Coupe, Aubergine

[timchar]

I think Steve has you on the right track... If your belt is making noise, something is up. How tight is it? Do you know how many bushings you used total? Tim

[rattlsnak]

What year is your SC? There are a few very important upgrades to the oil systems that can be done. Addresses the exact problem you have.

[ossiblue]

+1 on checking the belt tension first. There should be a total of 6 shims on the alternator shaft, dispersed between the belt pulley halves and/or between the nut and the outside pulley half. You can test your tension by pushing midway along the length of the belt and measure the deflection, or you can do a general test and see if you can turn the engine over by turning the alternator pulley, slowly (be sure the car is in neutral and the you turn the alternator nut clockwise only.) If you think the belt is too loose, remove the alternator nut using the proper pulley wrench, separate the pulley halves, remove one shim from between the pulley halves, replace the outside pulley half, and place the removed shim on the shaft between the outside half and the nut. Tighten the nut carefully ensuring the halves are aligned, and test tension again. Repeat if necessary.

If that doesn't solve the over heating and belt noise, you will need to hunt for another cause. under

[E Sully]

Besides making sure the fan belt is properly tightened, do you have an oil cooler in the front passenger fender? If so is it getting hot? When you had the alternator out, did you look to make sure no creatures had built a nest that might block the air flow?

[grovernk]

Thanks all I will check the tension and if the oil cooler is working, I'm also going to talk to the mechanic who did the alternator work

[LWJ]

I believe all SC's have the "trombone" oil cooler in the passenger front wheel well. Mine does. After you get the belt tension taken care of and double check the oil level (when running on a flat surface - use the dipstick - NOT the guage), drive around your neighborhood and watch the temps. If it warms up, check that the trombone is getting warm. There is a thermostat on the oil lines that can fail closed. Most likely not your issue - I vote for the fan belt - but it is worth checking.

Good luck.
Larry

[timmy2]

If the mechanic that did the work to your car did not put the air deflector at the back of the alternator on in the correct orientation, your engine would not get the correct airflow.

[grovernk]

So I just started the 911 up again after letting it sit from this morning, before i did this I push tested the alternator belt, seems pretty close to about a half inch of give, what I did notice when I started the car and watched the alternator belt is it isn't turning as smoothly as the other belts, it seems to have some play that is almost causing it to rattle. Could that be the issue?

I need to get the right tools to check and/or fix the tension

Appreciate all the comments

[ossiblue]

Originally Posted by grovernk

So I just started the 911 up again after letting it sit from this morning, before i did this I push tested the alternator belt, seems pretty close to about a half inch of give, what I did notice when I started the car and watched the alternator belt is it isn't turning as smoothly as the other belts, it seems to have some play that is almost causing it to rattle. Could that be the issue?

I need to get the right tools to check and/or fix the tension

Appreciate all the comments

That does sound like a too loose fan belt, and it would do no harm to tighten it a bit.

Timmy2 offered a very good point about the air deflector. If you see no change after a belt adjustment and the oil cooling is working, this is an area to follow up.

[timchar]

Bushings, meant shims... Tim

[timmy2]

Perhaps your mechanic did not know how to set belt tension with the shims when he put it back together. Your factory toolkit has the proper tools to adjust the belt. If you were nearby I'd do it for you...

[grovernk]

Hi All

Thanks again for the all the advice, the only thing more fun the being the proud owner of a 911 is how helpful all of you are. Unfortunately I am missing the factory tool kit, but I will find someone in San Francisco that can let me borrow one while I search for a set of tools.

Happy Driving All

Best
Nick

[rattlsnak]

Still havent answered what year car it is??

[grovernk]

Sorry all, 1978 SC, it had updated tensioners and pop off valve when I got it

The car had been sitting for almost 10 years, I had a good mechanic go through it all, he tuned it up, replaced the head studs, replaced some oil lines

Just had a Valero alternator installed about two weeks ago

Once I get this worked out I need to take out the clock and speedo, clock only works intermittently and odometer stopped counting on speedo, and the glovebox is stuck, hoping these are relatively easy fixes

All above being said, I live in SF but mechanic who has done the major work is about 40 minutes outside the city, can anyone recommend a shop in SF that I can take the SC too and check the belt tension since I don't have the tool

[LWJ]

You NEVER know what you will find in a 911 glove box! Kind of like opening Capone's vault.

Good luck!

Larry

[dyusem]

Originally Posted by grovernk

Sorry all, 1978 SC, it had updated tensioners and pop off valve when I got it

The car had been sitting for almost 10 years, I had a good mechanic go through it all, he tuned it up, replaced the head studs, replaced some oil lines

Just had a Valero alternator installed about two weeks ago

Once I get this worked out I need to take out the clock and speedo, clock only works intermittently and odometer stopped counting on speedo, and the glovebox is stuck, hoping these are relatively easy fixes

All above being said, I live in SF but mechanic who has done the major work is about 40 minutes outside the city, can anyone recommend a shop in SF that I can take the SC too and check the belt tension since I don't have the tool

I live in Mill Valley and can lend you my tool kit but I'm not returning home until Wed evening; I'll be traveling through SF on Fri to a mtg on the Peninsula and can drop it off then...

Aldo used to service my car when I worked in the city but he was in the process of moving recently and I'm not sure if he has landed yet but if he has I'd recommend him or The Stable. I don't have Aldo's contact info but just search for Aldo's + Porsche + San Francisco and you should find him.

Longer term I'd seriously consider Peter Wilms who has a small shop in San Rafael (Peter and Wolf Car Company). Peter worked at the Porsche factory for many years and he a straight shooter and knows the SC well.

Ping me if you need the tool kit and good luck chasing the problem down!
David