Oil temperature issues - again!

[Adam]

Background - Euro 911S, 2.7 (911/42), ducted and sealed fender mount Elephant Racing Widemouth cooler, electric fan, HeetSheets etc...

In approx 80ºF temps, the oil temps on the highway rose from their normal 185ºF to around 210º, just on steady cruising.

When I stopped for gas, I checked the oil cooler wasn't full of leaves or anything and checked the oil. It was low on oil... infact, barely showing on the dipstick, which I am ashamed of. I hadn't checked it in quite a while (considering it's a garage queen and I drive it infrequently - a couple of extremely fast 3-4 hr mountain runs since the last oil check), so I added almost 3 litres, which restored the level and I expected it to fix the cooling issue.

It didn't.

When I arrived at my destination, I checked behind the fan with a flashlight to see if critters had made a nest ontop of my motor. I felt the oil cooler lines, and they were warm, but not as hot as they have been in the past.

On the return journey, I found that suburban driving kept temps at around 180-185ºF (normal), but once I hit 60+mph on the highway, the temps would quickly surge upto 210-215ºF. I pulled off the highway near my home, and after about 10-15 minutes of urban cruising, the temps were back to normal.

I'm going to get a buddy with a gas-tester to see if my mix/CO and timing are set correctly, as this is very unusual. I was able to drive in 105ºF heat last summer without reaching 210º...

Any suggestions? Could I have created a large airpocket in the oil cooler?

[Jack Olsen]

Could be a sticky thermostat.

[Paulporsche]

Besides checking your mixture, check your timing and (do you have them?) points/dwell.

[Adam]

Thanks, guys.

I recently replaced the thermostat pistons forward of the rear wheel arch, but the engine mounted thermostat might be the culprit.

I checked the fan belt tension, too.

[Bill Verburg]

The forward lines should have been too hot to keep you fingers on them at 210

[Grady Clay]

Adam,

Your profile says “11-blade fan.” Which one? Is the fan pulley ratio 1.82:1?
The primary cooling for a 911 is air. If the oil cooling is stressed then probably the air cooling should be improved.

Now, 210F is definitely not too high. Actually every 911 engine should reach this temperature every time it’s driven. This is what evaporates the water and unburned fuel from the combustion gasses out of the oil.

The issue with high temperatures is when the cooling systems (air & oil) won’t keep the oil temperature at 210-220F. This is where you need to seriously address the cooling systems. If the oil temperature is 250F and above, damage is being done.

Best,
Grady