Odd problem for 911- engine temp (lack of)

[CMXI-SC]

With the out side air temp of anywhere from 40 to 80F my 82SCs engine temp never gets past 180 even with aggressive driving and trips of over 100 miles. I have the numerical gauge with the proper matching sender from our host so I believe the reading. In the past have never had a problem getting to 194 in less than 10 miles of driving . I have the Turbatrol front fender cooler and the piping is hot long before the gauge reads even close to warm. This leads me to think the thermostat in the right rear fender is stuck open. Has anyone run into this and if so do I need to drain the oil to replace the thermostat spring and cylinder?
Thanks in advance for your responses.

[pete3799]

You call 180F lack of heat?
Sounds normal to me.

[Hodgey]

sounds thermostat-ish to me too.....

I have to change a leaky seal on my thermostat housing, and the advice I got from this board was that there was no need to drain the oil completely although not sure about the actual thermostat itself...just my $0.02 worth

[boyt911sc]

Originally Posted by CMXI-SC

With the out side air temp of anywhere from 40 to 80F my 82SCs engine temp never gets past 180 even with aggressive driving and trips of over 100 miles. I have the numerical gauge with the proper matching sender from our host so I believe the reading. In the past have never had a problem getting to 194 in less than 10 miles of driving . I have the Turbatrol front fender cooler and the piping is hot long before the gauge reads even close to warm. This leads me to think the thermostat in the right rear fender is stuck open. Has anyone run into this and if so do I need to drain the oil to replace the thermostat spring and cylinder?
Thanks in advance for your responses.

Jack,

The auxiliary themostat under the R/R fender is normally closed below 186°F(+/- °F). It does not come into play until the oil temperature gets close to the 180° range. The numerical dash board gauge is notorious for giving faulty or inaccurate oil temp. reading. Get hold of an infrared temperature meter and start investigating. I would not suggest to remove and inspect the aux. thermostat until you find that it could be the cause. The temperature readings at different sections of the oil flow will give you a better understanding.

A simple way to test an auxiliary thermostat is in a water bath (oil is better). Heat the bath gradually with the thermostat complete submerged. Closely observe the sliding of the valve (from fully closed to initial opening). The test will confirm the condition of your thermostat. BTW, 180-190°F temperature for air cooled 911 engines is just approaching the 'optimum operating temp'. Keep us posted.

Tony

[CMXI-SC]

Thanks for the input guys:

Pete3799, I understood 194 is the optimal "normal running temperature" Am I wrong?

Hodgey, I believe I will get some drainage from the aux. oil cooler pipes however i wonder about the oil tank given the position relative to the thermostat.

Boyt911sc, Can't figure out how to completely submerge the T'stat to observe the sliding valve.

Thanks for your replies.

[boyt911sc]

Originally Posted by CMXI-SC

Thanks for the input guys:

Pete3799, I understood 194 is the optimal "normal running temperature" Am I wrong?

Hodgey, I believe I will get some drainage from the aux. oil cooler pipes however i wonder about the oil tank given the position relative to the thermostat.

Boyt911sc, Can't figure out how to completely submerge the T'stat to observe the sliding valve.Thanks for your replies.

Jack,

As I mentioned in my earlier post, I don't recommend removing the auxiliary thermostat unless the tests show an indication that it is not working right. Removing the hard oil lines and thermostat is a big undertaking. Then if you decide to inspect the auxiliary thermostat, removal is required.

Using the correct wrenches make the removal easier and faster. After you have disconnected the thermostat from the four (4) oil lines, it is time to investigate. Do not disassemble the AT (auxiliary thermostat) at this point.



Clean the unit before putting it in a water bath (or oil). It is normally closed and will gradually open as the temperature of the water bath goes up to 180°F plus and will continue to open wide as the temperature builds up. You could observe it clearly in hot water bath. Keep us posted.

Tony

[CMXI-SC]

Tony, Harbor Freight has a inexpensive IR temp meter and will pick one up . Where do you suggest I take readings from? Obvious is the filler neck at the oil tank when it is as hot as it will get. Then where? Shoot the Stat, front oil cooler? Don't want to pull the T'stat apart if not needed.
Thanks

[john walker's workshop]

my77 930 runs @ 190° normally. we had a 103° day a while ago and it got up to 210°. some just run cooler.

[CMXI-SC]

John, thanks for the reply. Understand all our cars have a comfortable "normal" range but 6 months ago the SC temp was running right between the 180 and 210 marks on the gauge ie. 194 so my concern is the change from my "normal".

[Bob Kontak]

I am jumping in a little late in the thread but you did not say and no one asked (that I can see from a quick scan) if anything was changed before an after the 194 vs 180 readings. Just a double check.

[CMXI-SC]

Bob, No, nothing changed. I am leaning twords 28 years of hot oil crud at the T'stat causing it to stay open. Your thoughts.

[CMXI-SC]

Bob
BTW I grew up in Warren. Get back once in a while. Great place in the summer.

[Bob Kontak]

Between Akron and Oil City/Franklin Pa have been my stomping grounds for a good chunk of my life. I actually live in Green, Ohio and found that Art Arfons' shop is about three miles from my house. He made the Green Monster that traded the land speed records with Craig Breedloves Spirit of America in the 1960's.

Drive thru Warren a lot seeing friends in Pa. Bummer not seeing the Youngstown Sheet and Tube factory humming.

[boyt911sc]

Originally Posted by CMXI-SC

Tony, Harbor Freight has a inexpensive IR temp meter and will pick one up . Where do you suggest I take readings from? Obvious is the filler neck at the oil tank when it is as hot as it will get. Then where? Shoot the Stat, front oil cooler? Don't want to pull the T'stat apart if not needed.
Thanks

Jack,

I also have the HF infrared thermometer and it works well for finding the thermal difference. Check the temperature of the oil lines (metal section) from engine, thermostat, cooler, oil tank, etc. At this time of the year (almost winter), I doubt if you could make the auxiliary thermostat to open for street driving unless you drive it for extended time (hours).

I've seen only over heating problems with the auxiliary thermostat in my very limited experience. That is the valve is stucked closed and preventing the warm oil to circulate through the auxiliary cooler. While it is possible that the thermostat is stucked open, which I doubt in your case, is to inspect it.

Confirm the temp gauge readings are similar to that of the temp obtained by the infrared instrument. Otherwise, your temp. gauge could also be a probable culprit. Do further investigation and keep us posted.

Tony

[CMXI-SC]

Tony,
Good to know the HF meter is usable. Will check tomorrow.

Bob,
Worked for about 3 mo. at Republic in Warren after high school. Decided I didn't want to do that the the rest of my life so enlisted in the Air Force ('65) Smart move.... Got to see more of Asia than I cared to. I go back and see the skeletons of the mills and remember the red skies at night. Know now why it's called the rust belt. Do miss the Fall colors.

[jwakil]

For all the people recommending IR temp meters as a quick and easy way to measure temps, think again. Those things depend on the emissivity of the surface you are measuring. So if you have a black surface you will get one temperature, if you have a white surface, you will get a totally different temperature (for the same temperature). You have to calibrate those things with a thermocouple or something, and then make sure the surface you calibrated with and the one you are measuring are the same. Or you have to know the emissivity of the surface to begin with. You cannot expect to measure both the black oil tank and brass pipes with the same settings.