Overheating

2000 CHEVROLET BLAZER
130,000 MILES • 4.3L • V6 • 4WD • AUTOMATIC
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DRAKE78
  • MEMBER
  • 1 POST
This last weekend I replaced the thermostat and heater core hoses because
one hose had a pin hole in it. while the old hoses where still attached to the
heater core i used compressed air to reverse flush the heater core and to
check for leaks. then flushed several times back and forth between the
hoses with water until water was clear. then installed flush kit, removed
thermostat, put housing back on and flushed the whole system until water
was clear. then installed new thermostat and refilled the system with new
coolant (green kind, not dex, i heard dex can case issues in older vehicle)
checked for leaks again. and started vehicle. let run with heat on until
operating temperature then ran at 2,000 RPMs for 5-10 minutes. no problems. drove
the vehicle back to its owner 10 miles away, no problems, then today owner
sends me a pic of the temperature gauge in the red. any idea of why this is
happening?
May 25, 2021 at 12:36 PM
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JACOBANDNICKOLAS
  • Experienced Mechanic
  • 110,240 POSTS
Hi,

Was there any dexcool left in the system? Dexcool is fine as long as you don't mix other types of coolant with it.

As far as the overheating, did it happen in stop-and-go traffic or at highway speeds? Is the clutch fan working?

Take a look through this link and let me know if anything is helpful:

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Keep in mind, a bad head gasket can also cause overheating.

I attached a link below for checking for a head gasket issue.

https://www.2carpros.com/articles/head-gasket-blown-test

Here is a link you may find helpful as well. It discusses common symptoms of a faulty clutch fan.

https://www.2carpros.com/articles/fan-clutch-symptoms

Let me know.

Joe
May 26, 2021 at 12:06 PM
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