1972T: Suddenly she's running too hot

[Stovepipe]

I'm looking after my friend's Porsche while he's overseas. I know, it's a tough job but someone's got to step up to the plate.

The car is a '72 911T with a later 2.7L motor with RS-spec pistons, webers, no external oil cooler.

Up until recently, it ran in the 180-210F range according to the gauge even during spirited drives, no problems. The car was in for service not long ago where they fixed a leaky fitting, and did an oil change. Since then it has run hot -- it reached almost 250F even on highway driving, with ambient around 75F. My buddy was puzzled by this but did not resolve the problem before he left.

I've had it out just twice for low speed cruising (not stop and go, mostly 20-40mph with the occasional freeway blast), and it gradually creeps up to 250F after about 1/2hr of driving, in 70F ambient temps.

Could the issue be simply an underfill of the oil at the last oil change? Checking on the dipstick it seems to fall between the marks, but it's hard to read it with the oil splashing by. Would being down 1/2L to 1L make a 50F difference in the engine's cooling abilities? I wouldn't have guessed, but i don't know these cars.

I promised my buddy I'd keep the car well-used, but assuming the gauge is not lying, 250F sounds too hot. He's running a non-synthetic Castrol 5W-20 oil I think.

Anything obvious I can check?

Thanks for the help.

[jwernquist]

I had a similar issue almost exact, what it turned out to be was the timing had advanced not sure why this happened etc but one we re-timed it all was back to normal.

Check timing, it shouldn't be too hard with the webers to remove the oil thermostat and test it with the old boiling water trick, might need replacement or cleaning etc.

Just a thought,

Jon W.

[moneymanager]

Your oil levels are fine; even a couple of quarts low shouldn't have the effect you are reporting. Got to be something else: timing, a mouse resident in the oil cooler, a thermostat failure, a rag left in the motor, etc. I wonder what the fitting they replaced was? Could it have been the oil temp sensor? If yes, might be worth swapping another one in to see what happens. Some years ago I replaced my sensor and the average temps dropped 20°...indicating a fair amount of variation in these units.

[Bobboloo]

Probably lack of proper air flow.

1. Check for oil on fan belt.
2. Check tension of fan belt.
3. Check for mice.
4. Check for missing or disconnected heater hoses.

Also check the timing like Jon suggested.

[ossiblue]

All good advice given and, please, report back anything you find, steps you've taken, and most important, the solution you found. Every problem solved, no matter how small it may appear, helps everyone on the board. Good luck.

[Stovepipe]

I still haven't resolved this. I don't have any shop manuals, and I've never set timing before. I did a search but it didn't turn up how exactly to check it, and what it should be set to. I will have access to a timing light in a few days. Can anyone point me to a link on how to set it, and to how many degrees advance?

No sign of any mice, fan belt is dry and doesn't seem to slip.

She's been running fine otherwise, except I had the car towed home after it got stuck in reverse and left me stranded! A search on Pelican revealed how to remove the reverse light switch and push the pin back in, unjamming the tranny and she was back on the road again.

These cars sure turn you into mechanics!


Thanks for the help.

[EarlyPorsche]

Get it to any mechanic that has timed any older engine and they can do it. Just wait until someone posts the correct timing degree and RPM's and give it to him. It would take no longer than 10 minutes if you give him a warm engine. Should be cheap and easy. I had an engine fall out of timing before too. Its easy to do with older engines.

[berettafan]

not your car.....i'd be very, very, very, very, very, very, very, very weary of dicking around with the timing and such.

[tobluforu]

Like stated before, get under car and look between cylinders and make sure there isn't a bunch of crap in between them. Is the fan shroud in good shape and still connected as well as all of the engine tin/deflectors? Did you take the external oil cooler off that would be located in the rear next to pass. side wheel well?
yes it could be lack of oil, does the internal oil gauge still work even though they can be deceiving?

[sballard]

This is a longshot but there were several posts awhile back about using lower viscosity oils to lower engine temps in hot climates. It seemed to have a surprisingly large effect Is it possible that the shop did the opposite - used a thicker oil than was in the car before it was serviced?

[Mysterytrain]

Running 5w20 ?? That can't be right..or good?