2002 Chevrolet Trailblazer cooling system

Tiny
RMBKJ340
  • MEMBER
  • 2002 CHEVROLET TRAILBLAZER
  • 230,000 MILES
Replaced both the water pump and fan clutch at the same time. One week later vehicle started overheating. Replaced thermostat & tested old one to be positive it was stuck shut. Found old thermostat to be stuck shut. Vehicle still wants to run @ 240 to 250 degrees. Have good flow through the radiator & everything looks to be in good working order. There is no check engine light. Will replace radiator cap because of build up on the inside of the valve. Cleaned it good and it made no difference so will just replace it. Can a radiator cap cause a overheating problem? Any help is greatly appreciated.
Sunday, June 2nd, 2013 AT 7:21 PM

2 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,330 POSTS
Before you get wrapped around the axle, have your mechanic perform a "sniffer" test at the radiator. He will draw air from the radiator through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If a head gasket is leaking the liquid will turn bright yellow. Combustion gases can pool under the thermostat and prevent it from opening. Thermostats open in response to hot liquid, not hot air.

Your vehicle is getting to the age too that you could have corroded cooling fins on the radiator. That will prevent it from giving up the heat to the surrounding air. A clue is the engine temperature will come down pretty quickly if you run the heater on the highest fan speed, and it will overheat faster when the AC is turned on.
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Sunday, June 2nd, 2013 AT 8:25 PM
Tiny
RMBKJ340
  • MEMBER
  • 3 POSTS
Shop says its the new thermostat. Dont believe that because I checked it before installing it. Sounds like an air pocket to me. Shop it going to install another thermostat & I dont think he is telling my mother in law everything. Sounds shady! After sitting all night she had no problem driving it to work, she said it hovered around 210 ish.
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Monday, June 3rd, 2013 AT 7:02 AM

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