I have an 1989 S10 blazer with a 4.3l V6. It has a G80 diff in the back and it's 2wd. Ever since spring started I started noticing the temperature on my truck starts rising when I'm at a traffic block or when I'm parked. It drops when I am on the move. In the last two years I've changed the AC clutch the heater core ,the water pump and the thermostat. I also checked the radiator hoses to see if there is any leak. There are none. It's maintaining the coolant level as well. I pressed the radiator hoses to see if they are pressurized after a drive and they are hard. I also changed the oil to synthetic around a month ago. I was wondering if someone could help me diagnose this issue.

Thank you.

  • 2
    Have you checked the radiator for flow? if it is partially blocked, that would cause it to overheat when stationary and be ok when moving due to the forced airflow. Check the radiator for obstructions to the airflow and to the water flow - especially water - has the radiator been replaced before? Or has someone used Barrs leaks or similar in the radiator?
    – Solar Mike
    Mar 26, 2019 at 15:46
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    I'm assuming you have a clutch fan up front? Can you spin it by hand easily? Is the fan shroud in place? Every thing you're stating leads to a fan issue (as long as temps go down when the vehicle is moving). If the fan turns easily, the clutch is most likely fried, which would cause a distinct lack of air flow through the radiator when the vehicle is stopped in traffic. Once moving, the air flow is plenty, so readily cools the system. Mar 26, 2019 at 17:01
  • @Pᴀᴜʟsᴛᴇʀ2 Hey paul. I just went to the parking lot and spun the fan, Yes it spins freely when i give it a whirl. I do have a question, wont the fan not spin when the engine is running if the clutch is fried?
    – goodcat
    Mar 26, 2019 at 18:27
  • @SolarMike Hello mike. Thank you for your response. I was thinking of taking it to the car wash today and shooting pressured water on the front of the radiator. Will that help with the blockage? or should i take the radiator out and drain the coolant and then run pressured water through it?
    – goodcat
    Mar 26, 2019 at 18:28

1 Answer 1


Since you have a clutch fan up front and it spins freely, I'd suggest your clutch is fried ... which considering how old the vehicle is, doesn't surprise me. The way the clutch is designed is it has a viscous coupler inside which, when the fan becomes warm, will lock it in place and pull more air. Even when the engine is completely cool, the fan should still have some amount of resistance as you spin it. If it spins easily at any time, the clutch is done and needs replaced. You can either find a replacement clutch at a junk yard (ie: pick-a-part; breakers; etc) or you can usually purchase them new from the aftermarket for a reasonable price. Considering what you've stated, this seems very likely and replacing the clutch should solve your overheating issue.

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