1999 GMC Sonoma

JKLEIN

MEMBER
1999 GMC SONOMA
6 CYL
4WD
AUTOMATIC
98,000 MILES

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?

Saturday, June 26th, 2010 AT 1:07 PM

3 Replies

KHLOW2008

MECHANIC
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?

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Sunday, June 27th, 2010 AT 3:47 PM

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.

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Sunday, June 27th, 2010 AT 8:06 PM

KHLOW2008

MECHANIC
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.

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Monday, June 28th, 2010 AT 7:06 AM