Re: [mg-tabc] Oil Temperature Problem

[Bob McClaren]

Listers,

While driving TC-3443 yesterday running about 50 mph, the oil temperature
gauge went from a normal 65-70 degrees C. to about 100 degrees C. Oil
pressure remained around 40+ psi under load and 20 when idling. Water
temperature remained around 70 degrees C. at all times. TC-3443 is
basically box stock, no internal modifications have been made to the engine
that I am aware of. I did change to the spin-on oil filter after one oil
pipe cracked.

When I noticed the oil temperature had gone up, I pulled off at the first
opportunity and examined the engine. There was no noticeable leaks under or
around the engine and both oil pipes were intact. (The last time the oil
temperature went up high like yesterday was when one of the oil pipe
fractured and I pumped most of the oil out on to the road.)

I checked the sump oil level and the dip stick indicated that I was low on
oil. Clean oil is hard to see. I added a quart of oil and watched the gages
until the oil temperature and water temperature were again indicating
approximately the same. (Actually the car drew a crowd of on-lookers and by
the time I had answered all of their questions the temperature had
subsided.)

The engine started right up and everything indicated as expected so I
continued the remaining 4 miles to my home. At traffic lights the oil
temperature marched up the gauge but would return to normal at speed.

I think the problem has to do with being low on oil...but where did it go?
Her normal engine leakage is not very bad, perhaps a silver dollar-sized
puddle coming from the rear seal when I shut it off. I have no indication
of any abnormal leaks and no noticeable oil burning smoke.

After church services this morning I will do some further investigation to
see whether the oil level is truly low or if the oil was not returning from
the valve cover area. Beyond that I have no explanation what is causing the
problem.

Clueless in Virginia Beach,

Bob McClaren
TC-3443

[CFritz7001@aol.com]

Bob,
It sounded to me from your description that, once you'd added oil, the
oil temp returned to and remained within its "normal" range, or nearly so; am
I correct??
Since oil has a relatively low heat-holding capacity, compared with that
of water, it seems quite logical to me that being low on oil would produce a
higher-than-usual oil temperature. (After all, if you are one quart low, you
are shy fully one-fifth of your sump's normal ability to absorb, contain &
release heat.) Seems to me that "low" oil level was the key ingredient.
As for some other factor which might have been at work, i don't know what
it could be. I don't think it could be the oil remaining too long in the
valve-cover/ head area, since there are so many good-sized oil-return
passages from there to the sump.
Where did the "missing" oil go?? Well, if it didn't leak out the bottom,
it must have either been burned in the cylinders, pushed out the "draft"
tube by pressure in the crankcas, or found its way into the cooling system by
way of a leaky head gasket/cracked head. If it wasn't one or a combination
of these things, I'm really stumped.
Hope this helps,