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Over heating
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Author:  Jimmyb45 [ Fri May 29, 2015 9:33 pm ]
Over heating

Question on over heating on a 99 Olero 3.4 , I have put in a new thermostat , new radiator cap , & a new fan relay module & still over heats , only thing left is the PCM ? Thanks inadvanced

Author:  carriedi [ Sat May 30, 2015 2:21 am ]
Re: Over heating

wiring diagram for the fans:

http://econtent.autozone.com:24991/znet ... 23ae8e.gif

What's happening and when does it overheat? Overheat idling? overheat while driving? do the fans come on? Low speed? High speed? How's your coolant level? Are you loosing fluid? How high does the radiator pressure get? Do you have a plugged radiator? Do you have a blown head gasket?

Author:  Jimmyb45 [ Tue Jun 02, 2015 9:10 am ]
Re: Over heating

carriedi wrote:
wiring diagram for the fans:

http://econtent.autozone.com:24991/znet ... 23ae8e.gif

What's happening and when does it overheat? Overheat idling? overheat while driving? do the fans come on? Low speed? High speed? How's your coolant level? Are you loosing fluid? How high does the radiator pressure get? Do you have a plugged radiator? Do you have a blown head gasket?


Sorry it took so long to get back with you. Car was tested for blown head gasket ( OK ) there, fluid level ok, fans com on, throws out fluids when sitting & gets hot & or traveling, cap is a 15 lb gm cap, thermostat , fan relay module all gm. Coolant is always full, radiator put in 6yrs ago. That about it.

Author:  carriedi [ Tue Jun 02, 2015 10:22 am ]
Re: Over heating

If the cooling stays full and the fans are working then there should be a flow problem. Water pump not moving coolant or thermostat not allowing coolant flow of the radiator is plugged up. But you say that it throws out fluid. that should make the system not full.

from a cold start, how long does it take to get hot? How hot is hot? Do the fans come on as the temp reaches about 3/4 on the gauge?

With a new thermostat and all the other stuff you replaced, and the fans working properly, I would look at the radiator for cold spots, the water pump for flow, check the pressure being built up in the cooling system and and double check the gasses out of the radiator for hydrocarbons.

Author:  Jimmyb45 [ Tue Jun 02, 2015 10:38 am ]
Re: Over heating

carriedi wrote:
If the cooling stays full and the fans are working then there should be a flow problem. Water pump not moving coolant or thermostat not allowing coolant flow of the radiator is plugged up. But you say that it throws out fluid. that should make the system not full.

from a cold start, how long does it take to get hot? How hot is hot? Do the fans come on as the temp reaches about 3/4 on the gauge?

With a new thermostat and all the other stuff you replaced, and the fans working properly, I would look at the radiator for cold spots, the water pump for flow, check the pressure being built up in the cooling system and and double check the gasses out of the radiator for hydrocarbons.


OK ! will do more checking, Thanks

Author:  Jimmyb45 [ Wed Jun 03, 2015 9:08 am ]
Re: Over heating

Jimmyb45 wrote:
carriedi wrote:
If the cooling stays full and the fans are working then there should be a flow problem. Water pump not moving coolant or thermostat not allowing coolant flow of the radiator is plugged up. But you say that it throws out fluid. that should make the system not full.

from a cold start, how long does it take to get hot? How hot is hot? Do the fans come on as the temp reaches about 3/4 on the gauge?

Did more digging in to my over heating on my 99 olero. To make a long story short, i put in a new PCM & that took care of my problem, my old PCM was bad, it was not doing it's job, every thing is back to norm, NO over heating just normal stuff, i wanted to start out with the cheep way to go first then the HIGH price stuff for last. Thanks to all that put in their in put on this, i do Appreciate it, thanks again, i am glad i found this program. Jim
With a new thermostat and all the other stuff you replaced, and the fans working properly, I would look at the radiator for cold spots, the water pump for flow, check the pressure being built up in the cooling system and and double check the gasses out of the radiator for hydrocarbons.


OK ! will do more checking, Thanks

Author:  Beginnermechanic [ Fri May 20, 2016 11:05 am ]
Re: Over heating

I have a 04 alero that is overheating... The fans do not come on i have to turn the ac on.. When it does overheat there is no preasure on the reservoir. How would i know if my water pump dont work or the thermastat. ..or how would i know if i have a crack head

Author:  carriedi [ Fri May 20, 2016 8:40 pm ]
Re: Over heating

if your engine is overheating but it doesn't build up pressure in the cooling system, you need to check for a leak. When the coolant heats up it expands. If it expands in a closed system it builds up pressure. If the coolant gets hot but doesn't build up pressure in the system then the pressure is escaping somewhere. you should have the cooling system pressure tested.

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