I think my SC is still running Too Hot

[Joe Bob]

Just remember....oil coolers don't make the engine run cooler. They keep them at operating temps longer. Operating temps are a function of the thermostat. Thermostats open around 180-190F.....when they are working correctly. If they open higher, then that is the temp your engine will operate at.

Temps climb when you exceed the coolers capacity of maintaining operating temps. Fans on a cooler are only for bumper to bumper traffic and actually impede air flow when they are not operating.

[911SauCy]

Originally Posted by Joe Bob

Just remember....oil coolers don't make the engine run cooler. They keep them at operating temps longer. Operating temps are a function of the thermostat. Thermostats open around 180-190F.....when they are working correctly. If they open higher, then that is the temp your engine will operate at.

Temps climb when you exceed the coolers capacity of maintaining operating temps. Fans on a cooler are only for bumper to bumper traffic and actually impede air flow when they are not operating.

Stupid question of the day...can I change to a cooler t-stat?

It does get hotter when trashing is in order.

[Ronnie's.930]

Originally Posted by 911SauCy

This thread got me thinking...and so has my car since it's finally sorted and I have time to pay attention to how its driving instead of awaiting the next issue.

My '78 SC runs as pictured, took this after 20 minutes of driving, couple red-line shifts but mostly hanging around 2500-3500rpm. Car has completely stock trombone but I've added the air scoop. Its 75-80F here today.

I can't find the degree numbers mentioned, the picture is normal operating. It will go up another needle width if stop-go or I'm really thrashing it.

Is this normal for my set-up

Based on your picture, and the gauge information in the following thread, your engine oil is at pretty much the perfect temp (between 200-220). There are people on this forum that will tell you anything above 180 is bad, but they are mistaken and simply relaying the emotional responces they are having to a generalized idea in their heads regarding what is "too hot" (not to mention they are second guessing the very people that designed and built the engines in the first place).

Neat option for real numbers on the oil temp gauge

[Joe Bob]

I wouldn't....if the t-stat is working correctly keep it as-is. Test the t-stat, check gauge accuracy. If you are getting temps higher than 220F with 'normal driving' and the t-stat is working correctly and you don't have any internal issues.....then you need to add a front cooler.

Not cheap.....I would consider checking stuff first...

[911SauCy]

Originally Posted by Joe Bob

I wouldn't....if the t-stat is working correctly keep it as-is. Test the t-stat, check gauge accuracy. If you are getting temps higher than 220F with 'normal driving' and the t-stat is working correctly and you don't have any internal issues.....then you need to add a front cooler.

Not cheap.....I would consider checking stuff first...

Roger that.

[911SauCy]

Originally Posted by Ronnie's.930

Based on your picture, and the gauge information in the following thread, your engine oil is at pretty much the perfect temp (between 200-220). There are people on this forum that will tell you anything above 180 is bad, but they are mistaken and simply relaying the emotional responces they are having to a generalized idea in their heads regarding what is "too hot" (not to mention they are second guessing the very people that designed and built the engines in the first place).

Neat option for real numbers on the oil temp gauge

Perhaps I'm just freaking out because the 35y/o what was once a complete disaster is now working fine freak-outs have set in.

Coming from a supercharged liquid cooled unit...this silly stuff is still all new to me.

In my head the oil temp=coolant temp...

[mca]

Originally Posted by 911SauCy

This is what's in my '78SC. Those #s are really in there. There is a center line @ 9 O'Clock.

Top of bottom hollow white box looks to be 60C and the beginning of the red is 150C

Here is a better picture:
911 Gauge module overlays

Hard to tell from the angle of your pic, but slightly passed 9 o'clock puts you at 200 degrees. Your gauge has a small area between 200 and 240. To me it looks like you are at 210ish.

They are using your exact gauge in their photos so I'm not sure why you feel you are running hot.

[Ronnie's.930]

Originally Posted by 911SauCy

Perhaps I'm just freaking out because the 35y/o what was once a complete disaster is now working fine freak-outs have set in.

Coming from a supercharged liquid cooled unit...this silly stuff is still all new to me.

In my head the oil temp=coolant temp...

That makes sense. One thing to consider regarding oil v coolent temp: most engine oil will not boil (flash point) until they reach temps above 400 degrees - some considerably higher. This is just a comparison beteen coolant and oil temps - not saying it is safe to run with 400 degree oil temps in any engine.

[boyt911sc]

For peace of mind you have to check and inspect the engine and auxiliary thermostats operating conditions when you are having doubts about your operating engine temperature. Adding cooler without verifying or checking the thermostats is not a prudent course of action.

Picture below illustrates the three (3) different behavior or condition of the auxiliary thermostats. On the left most is the thermostat at fully stuck close condition, the middle is at the half-way open, and to the right is a normal operating thermostat (fully open). Water bath test temperature was between 185°F - 190°F.


Thermostats out from the water bath.


Auxiliary thermostats tested:


Tony

[911SauCy]

Originally Posted by mca

Here is a better picture:
911 Gauge module overlays

Hard to tell from the angle of your pic, but slightly passed 9 o'clock puts you at 200 degrees. Your gauge has a small area between 200 and 240. To me it looks like you are at 210ish.

They are using your exact gauge in their photos so I'm not sure why you feel you are running hot.

It's more of I'm just not exactly sure where it's supposed to operating than whether or not its running too hot.

Thanks for the info MCA.

[Joe Bob]

Porsche and VDO have been supplying "vague gauges" since the early 70s. Irksome at best. You want accuracy you change the gauge to a more precise device or use an outside device to calibrate.

The hand held IR temp gauge is cheap. Shoot the beam at the oil tank, base of the engine and the oil lines.

[Ronnie's.930]

Originally Posted by 911SauCy

It's more of I'm just not exactly sure where it's supposed to operating than whether or not its running too hot.

Thanks for the info MCA.

Oil operating temperature of 200-210 degrees Fahrenheit is about as perfect as you can get - among other things, this temp helps to burn off condensation, gasoline, and other contaminates in the oil . . .