Temp. Indicators

Tiny
SHIRSCHBERG
  • MEMBER
  • CHEVROLET CAPRICE
Hello - I have a 1991 Chevy Caprice 351 Eng. With 80,000 miles.

For the last few months the temperature guage has been acting very strange. Soon after I start using the car each day (especially on highways) the temp. Guage goes all the way past the red zone. Also, the overheating light & the service engine light come on. This happens for about 1 minute, then the temp. Guage quickly falls back to the normal area. And both of the indicator lights go out. There is absolutley no evidence of overheating. My mechanic has changed the entire instrument cluster in addition to the Buffer. My mecanic has also tested the electrical circuts as well as the system codes but everything looks normal. There has been no lose of anti-freeze & the
radiator remains at the correct level. Sometimes after the car has been parked for an hour or more the temp. Guage goes to the 3 quarter mark and then falls back to normal. The car drives OK.
but because of this problem, I have no real way of knowing if &
when the car might be overheating - until it's to late.

This problem has really got me stumped. Any ideas as to what
the problem might be would be greatley appreciated.

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Tuesday, March 20th, 2007 AT 5:04 PM

5 Replies

Tiny
M_H_RITZEL
  • EXPERT
Have the thermastat checked or replaced, the thermastat could be binding up and staying closed to a point then opening, just before it overheated.
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Tuesday, March 20th, 2007 AT 5:29 PM
Tiny
SHIRSCHBERG
  • MEMBER
M_J_RITZEL, Thank you for your reply.

I neglected to mention in my original post, the thermostate has already been replaced when this first strated to happen. I told my
mechanic that I thought the thermostate might be sticking, but he
strongly feels that they car is not shwing the right symtoms for
a bad/malfuntioning thermostsate.

When my mechanic is puzzeled & troubled about problems it is
very strange, as he is extremely experienced. He has been in the
business for over 20 years. Now he could also be headstrong and
not want to admit that it might be as simple as a thermostate. But that just does not seem like him. My family has been using him
for years.

Do you think I should I just insist that he changes the thermostate again?
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Tuesday, March 20th, 2007 AT 7:21 PM
Tiny
SHIRSCHBERG
  • MEMBER
M_J_RITZEL - A little more information.

This problem only happens after the car has been parked for
an extended period of time (at least an hour) and especially
after parking it overnight.

After I have been driving it for a while, the indicators are normal.
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Tuesday, March 20th, 2007 AT 7:33 PM
Tiny
MACHEDBERG
  • MEMBER
Has the same problem for 2 year now.

Had a problem with sometimes there was coolant leakage under the car! Could t find any leak. And the expander was ok level. After a while I was in need to refill. Long time later I locate the leak, it was the waterpump.
And the same morning (a very cold morning, burr.) The motortemp whent up. # %% , Got the pump, and when I checked the waterlevel there where not problem.
I got a serviceshop to fix the change of the pump.
And when I was driving away the temp went up to red.
Talked to the serviceperson and they could't explain else that it was airbubbles.
Well that was 2 years ago, hade a new leak somewhere, finally located it to the radiator! Got a new one and also change the upper and lower tube also. And the upper was cracked (3 year old).
Well now it should work! Did a testrun and it seemed ok. No leaks. Next day, was stopping by a gasstation for a coffe. Come back to the car and a saw dripping again. What the. Open the hood and saw that the clam (new) had busted and the tube was lose to the radiator. Hmmm, got a new better clam and tied it up.
Now it was ok. For some day. Dripping again.
Toke apart and found that the new radiator was leaking.(Canadian! ) Ok. Away to buy a new one, to change, also got som coolant clean-up, flushed the system a few times, mounted the new radiator and use the clean-up, and when it was done, I have not been needed for refilling the coolant. But I still have the problem with the sensor is going skyhign. (Change the sensor earlier) If I use only Cold in the airflow, then the temp is ok. If I use a little bit of heat then the temp goes up and after a little while (as like the termo opens, change it also twice) it goes down. If I have full heat on the air, it feels like it takes some time to be really hot, even that the temp says "red".

When I try to explain to the technicians they do not understand either. But I think that when I use the heater, then I change the watercirkulation to go thrue the heater and strait out to raidiater. And therefore there are not enough pressure for the water to circlutate.
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Wednesday, October 31st, 2007 AT 8:43 PM
Tiny
M_H_RITZEL
  • EXPERT
Have the system pressure checked to see if there is any internal leaks. The majority of overheating problems are loose belt, thermastat, clogged system, lack of enough coolant or bad sending unit. Lose of fluid can be from leaky hoses, loose clamps, radiator leak blown head gasket, water pump. With bubbles air is getting into the system from somewhere in the engine or the coolant is boiling.
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Friday, November 2nd, 2007 AT 9:18 AM

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