sunfire overheating but radiator is cool.

[disturbed]

Hello my daughter recently purchased a 2000 sunfire(2.2L). The heat was blowing cold air. When i removed the thermostat house so i could check it there wasn't one present. I installed a 180 degree thermostat. The car now has heat until it hits around 195 on the gauge then it looses heat. Temp gauge will climb to just under 260. The radiator is cold however(i can place my hand on it). It appeared to have a new water pump on it but i replaced it anyway. I've borrowed a block tester kit from a buddy. Has anyone ran into this issue,if so what was the fix? My gut tells me that if it's in the head the radiator would still be getting warm.

 

[disturbed]

radiator fan does kick on

 

[melsg5]

sounds like you have air in the cooling system

 

[disturbed]

I had bleeder screw open when filling(threw reservoir) . I've also tried to burp it. Is there a better way to fill it. Ie remove upper radiator hose and ensure that the radiator is full and not air locked ?

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[melsg5]

this is on a 98 cavalier which may be similar

http://www.justanswer.com/chevy/3j0pb-bleed-cooling-system-98-cavalier-2-2-eng.html

 

[sunfire2door]

Faulty thermostat? I've seen new thermostats fail just like that. Make sure you burp the cooling system properly.

 

[disturbed]

@sunfire I've tried 2 both with same results....haven't had a chance to work on it over the past few days. I'm going to block test it tomorrow or wednesday.

 

[disturbed]

got a chance to use the block tester today.....fluid turned from a deep blue...to a light blue/greenish....i'm guessing that indicates the presence of combustion gasses.

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[sunfire2door]

Rats! How many miles on the engine? Is the oil milky?

 

[disturbed]

odometer shows 120,000. I don't think it's the original motor though. Valve cover has yellow writing on it(makes me think it's a junkyard motor). Hood bolts have been removed at some point. The oil is not milky.

 

[tuck69]

thermostat

my mom has the same car and did the same thing, I drilled a tiny hole in the edge of the thermostat and that solved the problem. It had a vapor lock that I couldn't get out until I did that.
the way I knew that it was a vapor lock was the temp went up to about 200 then jumped to 260, it should of went up steadily, not jumping.
the hole allows the air out below the thermostat. good luck

 

[disturbed]

i pulled thermostat so the car could at least be driven.....how big a hole did you drill and where on thermostat was it located(top??)

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[melsg5]

this link shows a drilled thermostat

http://www.cherokeeforum.com/f2/photo-thermostat-drilled-holes-25710/