91 Honda Civic over heating

Tiny
GLADYSONFIRE
  • MEMBER
  • 1991 HONDA CIVIC
I have had problems with the tempature running hot. I have changed the heater core which had a small leak and thermostat. Took out for a test run and it over heated and blew out the top radiator hose!

Any suggestions on what else it could be?
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Monday, June 18th, 2007 AT 6:41 PM

5 Replies

Tiny
BRUCE HUNT
  • EXPERT
Has the car been losing coolant? Does the coolant level drop?
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Monday, June 18th, 2007 AT 11:23 PM
Tiny
GLADYSONFIRE
  • MEMBER
It was losing coolant before we changed the heater core and hose leading from it. It does not seem to be since then. Just running very hot to the point of complete over heating yesterday.
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Tuesday, June 19th, 2007 AT 7:08 AM
Tiny
BRUCE HUNT
  • EXPERT
After you did the work, did you purge the system of air? You did put a new thermostat in I believe you said, have you ever added stop leak or such to the system?
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Tuesday, June 19th, 2007 AT 7:54 AM
Tiny
GLADYSONFIRE
  • MEMBER
Yep we tried that. After looking at it more tonight we have figured out that the cooling fans are not coming on. How do you figure out if it's just the switch or the fan it self?
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Tuesday, June 19th, 2007 AT 6:36 PM
Tiny
ALWAYSLEARY
  • MEMBER
Go to the relay box near the battery. Open it up and find the fan relay. You have to jump two pins. I don't remember if it was 3 and 7 or 5 and 7. Anyway, do some research online on how to jump your fan relay pins. If the fan comes on after jumping the pins then your fan sensor that is in the coolant system is either no good, or you have a pocket of air built up in your coolant system around the fan sensor. When there is a pocket of air built up around the fan sensor the sensor doesn't know how hot the coolant is since no coolant is running over the sensor itself. You need to run the engine and use the little piss valve that is near the top radiator hose on the engine. Open this valve slowly with a box wrench or a socket wrench set. Let the coolant flow out until you see a steady stream. Make sure your radiator cap is on tight. You should never open the radiator cap. You should use your overflow res to replace antifreeze. Make sure the overflow res is filled up to the fill line. Let the car cool down. If you notice that the overlfow res is empty or lower than where you filled it too, then your coolant system has replaced the air pocket with antifreeze. Fill the overflow res back to where it it supposed to be, start your car, let it run and make sure the hoses get hard when the car is at operating temp. If the hoses are soft while the car is running hot, then you have an air blockage and that is why your fan is not coming on. Always bleed that valve if this keeps happening. You may need to have your head gasket replaced.
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Sunday, June 24th, 2007 AT 2:19 PM

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