1999 GMC Sonoma

1999 GMC SONOMA
98,000 MILES • 6 CYL • 4WD • AUTOMATIC
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JKLEIN
  • MEMBER
  • 2 POSTS
I have replaced thermostat, flushed system, put on 2 800 cfm cooling fans. the motor will flush through once then starts to overheat. Any suggestions on what can be done?
Jun 26, 2010 at 1:07 PM
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KHLOW2008
  • CAR REPAIR CONTRIBUTOR
  • 41,814 POSTS
Hi jklein,

Thank you for the donation.

Can you describe your problem in more details? I am not able to understand the actual situation.

Do you have coolant losses issues?
Jun 27, 2010 at 3:47 PM
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JKLEIN
  • MEMBER
  • 2 POSTS
From cold, the motor heats to about 200.(195 thermostat) The thermostat opens, coolant cycles once, then heats up and overheats.
I've replaced thermostat 3 times, had the system flushed by the dealer, the only thing not replaced is the waterpump and radiator.
Any suggestions on what to do next?
Thanks.
Jun 27, 2010 at 8:06 PM
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KHLOW2008
  • CAR REPAIR CONTRIBUTOR
  • 41,814 POSTS
Try removing the thermostat and running the engine to test if it still overheats.

It is possible for a bad water pump to be the cause. The fins might be worn resulting in insufficient coolanr flow.

If it is the radiator, the air blowing out from the fans would be cool whereas the upper hose would be hot and lower hose cool.
Jun 28, 2010 at 7:06 AM
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