SC Running Really hot

[dandrews64]

So with the summer heat coming I need to solve this problem that I've ignored during the winter.

My '82 SC with 139K miles runs hot. Engine is bone stock.

After about 30-60 minutes of 80mph cruising in 80+ degree heat, the temp guage registers between the upper white hash mark and the red zone (10:30, if the guage were a clock). Let me know if I need to post a pic of the guage.

On even hotter days and longer drives it reaches the bottom of the red zone (11 o'clock). This has to be bad. During the cold weather, it has run in the normal temp zone (9 o'clock)

Data:
- The oil lines and trombone cooler are really hot to the touch.
- Only one small dent in the line, and in my non-expert opinion can't be having a material impact - or can it? You tell me. Can post pic if needed.
- Have installed the oil cooler scoop in the marker light
- I run 20/50 non-synthetic Castrol and yes, the level is up.
- The fan belt is tight. Is there a tension/free-play test to check it?
- When I did the plug wires I was lazy and did not use the rubber wire routers that plug into the shroud. So there are 3 or 4 small holes in the shroud where the routers should be. Would this have a material impact?
- The part number on the fan/shroud is 930.XXX.XXX. Does this mean a PO upgraded to a turbo fan?


Should I bite the bullet and try the oil thermostat ? (yuk, PITA)

I've heard an old/bad catalytic converter can make it run hot. Would that be bullet #2 to bite? Car seems to have good power, so it doesn't drive like the exhaust is clogged, but I also wouldn't know what it *should* feel like. It's my first 911.

Other ideas, from this crowd of experts?

[edward993]

Wow, that IS hot for only 80+ degrees and at cruising speed...and at colder temps I NEVER see even close to 9:00, even stuck in traffic. I'd check the fins and engine area completely (PITA, but behind the fan, too) to make sure you don't have debris (or a mouse's den) stuffed up in the crevices. Then maybe check that you're not running too lean. Once you find the problem, it may be worth it to you to get a cooler (Jared Fenton mentioned in another thread he found a Euro 28-row cheap ...might be a poss for you). Hope this helps. Post back your findings ...I'm curious, anyway.

Edward

[sammyg2]

Yup, something is seriously wrong. Under those conditions my SC never gets off the white mark.
Either the oil isn't flowing as it should, or it is getting too hot in the first place. Is your engine running extra lean?
I think I'd pull a spark plug or two and see what they look like, if its running lean that would make it run hotter.
A useaful tool is an infra-red temperature gun. You could map out the temperatures to make sure you have a temperature drop across the lines to the trombone cooler.

[aigel]

Do you park the car where critters could get to it and move in? I have seen mice set up camp on top of the cylinders - not good - but you can usually smell that.

Any chance it is running lean?

My bet is a thermostat.

George

[oneblueyedog]

My engine before rebuild had this problem. It was a non functional engine thermostat.

[Miguel Antonett]

Just too hot. I would not drive it that hot becuse if you encounter some traffic during your ride it could really hurt the engine... however, no panic yet, it could be as simple as a faulty sender or temp. gage, thermostat... Go by elimination until you get to the real problem.

[kstylianos]

It was a non functional engine thermostat.

BTDT, this was the problem. Use a pyrometer on the oil lines, or better yet on the temp sensor to verify your gauge readings. You were running between 250-300 degrees.

[dandrews64]

Thanks for all the ideas.

Can't wait to get home, open the Bentley book and start poking around.

[Chuck Moreland]

It is likely the on-engine thermostat. Test by carefully reaching under the on-engine cooler and touching it. It should be too hot to keep your hand on it. Watch out for the exhuast.

[Howard M]

Could it be that old problem with some SC's: cavitation in the oil pickup? This is cured by installation of an updated engine drain plate that includes a reformed strainer screen, which sacrifices the drain plug (I think). This problem usually happens at high RPM and is accompanied by loss of oil pressure.

Howard

[KNS]

The oil-pick-up problem was with 78 and 79s. I would check behind the alternator as others have suggested. Also the gauge itself to see if it's reading correctly and matched with the sender.

[Mysterytrain]

How long have you had the car and did it run cool before? My 78 before the major rebuild ran hot. When we tore it down we saw the engine oil cooler was coated and clogged from an oil leak. Might be something for you to look at while you are investigating the thermostat.

[ubiquity0]

Check the accurancy of your gauge & sender.

[Paulporsche]

did this just suddenly start? Make sure your timing is not too advanced. Is your WUR OK?

[air-cool-me]

problem found...


- The oil lines and >>>>>trombone cooler<<<<< are really hot to the touch.


euro 28 rows are cheap!

but if it was fine before... my guess is the t-stat.

[echrisconnor]

That's hot! If all is well with the engine, the trombone should keep this thing cool unless you're driving the pi$$ out it. Check the internal cooler to see it's circulating oil. If so, before you put in an additional cooler, find the problem.

I suspect if you richen and retard, you'll see a difference. Check your timing and make sure you're not too far advanced. Then if you haven't had your mixture checked do so or, just richen by an 1/16 - 1/8 of a turn.

[Carl83911]

Originally posted by air-cool-me
problem found...


- The oil lines and >>>>>trombone cooler<<<<< are really hot to the touch.


euro 28 rows are cheap!

but if it was fine before... my guess is the t-stat.

__

I don't see that as a problem. The oil lines going to the trombone cooler should be hot after a long drive. That's an indication the thermostat is openning.

[sammyg2]

I'd venture to guess that the trombone cooler and lines shouldn't be hotter than 210 or so under those conditions.
Upgrading to a better cooler would be a band-aid in this case, trying to treat the symptom and not the disease.

[aigel]

There is two thermostats on your car. The one to the trombone needs to open, but also the one letting the oil go to oil cooler on the engine. That thermostat is located on top of the engine case in the front.

George

[air-cool-me]

"The oil lines and trombone cooler are really hot to the touch. "


then at least that T-stat is working...