Overheating 260+!
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Joined: Jul 2006
Posts: 97
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From: Cape Coral FL
Overheating 260+!
stock '02 34k miles...this overheating problem has got me stumped......I have replaced the thermostat......no luck......replaced the water pump and removed the thermostat and it's still overheating......fans work fine and turn on at correct temps......radiator is free of debris....oil is fine and no white smoke.......checked flow through the radiator with a water hose to check for some type of blockage and all is fine......this did start out as an intermittent problem...would get the coolant overtemp on the DIC I would pull over and let it cool....then drive again and the temps woulld start rising to overheat and then for no reason would drop off in 3-4 sec's back to 220 and be fine for a week......unfortunately now it just overheats everytime I start it up.........so any ideas as to what this could possibly be......something I've overlooked.....thanks!
Le Mans Master
Joined: Feb 2006
Posts: 5,267
Likes: 40
From: Phoenix AZ
Put a new thermostat back in.
When it "overheats", check the real temp of the radiator with a thermal probe.
Is the temp gauge accurate?
Is the bottom radiator hose collapsing?
If all else fails, when COLD COLD COLD, open cap and let pressure out. Put cap back on, start engine and rev a few times and see if there is instant pressure on the hoses.....as in blown head gasket.
When it "overheats", check the real temp of the radiator with a thermal probe.
Is the temp gauge accurate?
Is the bottom radiator hose collapsing?
If all else fails, when COLD COLD COLD, open cap and let pressure out. Put cap back on, start engine and rev a few times and see if there is instant pressure on the hoses.....as in blown head gasket.
Thread Starter
Advanced
Joined: Jul 2006
Posts: 97
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From: Cape Coral FL
Originally Posted by gpracer1
How fast from start up when cold does it overheat?
When cruising at 70 or in stop and go under 35?
When cruising at 70 or in stop and go under 35?
7th Gear
Joined: Sep 2006
Posts: 7
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I had the same problem recently on my Camaro and the diagnosis was that a blown head gasket/cracked head was causing compression into the radiator. Might want to check for that next. Hopefully this is not the problem tho 
Good luck
Good luck
Thread Starter
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Joined: Jul 2006
Posts: 97
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From: Cape Coral FL
[QUOTE=BlackAFZ06]I had the same problem recently on my Camaro and the diagnosis was that a blown head gasket/cracked head was causing compression into the radiator. Might want to check for that next. Hopefully this is not the problem tho
Any idea how to check for that? Someone mentioned using a NAPA block dye test for hydrocarbon??.....did your problem start out as intermittent like mine?
Any idea how to check for that? Someone mentioned using a NAPA block dye test for hydrocarbon??.....did your problem start out as intermittent like mine?
Drifting
Joined: May 2000
Posts: 1,917
Likes: 3
From: Southern NH
Make sure you don't have an air pocket in the system. It can prevent the water pump from properly circulating the coolant and result in the overheat condition.
Do a search on this - there should be a post on how to fill the coolant system to prevent this.
Do a search on this - there should be a post on how to fill the coolant system to prevent this.
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Racer
Joined: Nov 2002
Posts: 412
Likes: 1
From: CT
You could always try another thermostat, too. Might be a waste of time, but they're not too expensive and you might have picked up a dud... 5 minutes in the garage from stone cold to overheating is very fast. If the thermostat never opened, it would heat up fast... maybe not that fast though. The air pocket idea suggested above sounds like a possibility, too. Did you do a coolant flush or have one done by someone else before this started happening?
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,820
From: Charlotte, NC (formerly Endicott, NY)
Have you put your hand on the upper radiator hose to see if hot coolant is flowing into the radiator? With the stock thermo I was able to feel hot water beginning to flow at an indicated 150 degrees on the DIC.
Bill
Bill
Pro
Joined: Aug 2001
Posts: 724
Likes: 0
From: West Palm Beach FL
When you took out the thermostat did you block off the large 1 1/8 inch hole in the water pump? This is the bypass hole...without a thermostat you will be bypassing large amounts of fluid. If you look at the thermostat there is an extra "foot" . when it opens the foot actually blocks off the large whole I am talking about......that is why it needs to be blocked when you remove the thermostat.
Safety Car
Joined: Jun 2004
Posts: 3,555
Likes: 739
From: panama city beach florida USA
St. Jude Donor '09
like the man say put that stat back in. when the fans come on are they blowing hot air. a hose test in rad isnt the best way ,pull the rad and take it to a rad shop they will flow test it.if you have access to a rad psi tester pump it up to 12/14 lbs cold start motor and hold at 1500/2000 rpm for 1 min if psi goes up a compression leak is poss. good luck
Le Mans Master
Joined: Feb 2006
Posts: 5,267
Likes: 40
From: Phoenix AZ
From cold to overheating in 5 min is way too fast.
Im thinking head gasket leak or cracked head/block causing air in the system. You need a cooling system pressure tester and start from cold and see how fast and high the psi gets.
Im thinking head gasket leak or cracked head/block causing air in the system. You need a cooling system pressure tester and start from cold and see how fast and high the psi gets.
Melting Slicks
Joined: Jul 2004
Posts: 2,226
Likes: 65
From: West hills California
Originally Posted by JC in XTC5
Make sure you don't have an air pocket in the system. It can prevent the water pump from properly circulating the coolant and result in the overheat condition.
Do a search on this - there should be a post on how to fill the coolant system to prevent this.
Do a search on this - there should be a post on how to fill the coolant system to prevent this.
Burning Brakes
Joined: Aug 2006
Posts: 1,217
Likes: 5
From: Stark County Ohio
FYI – Keeping the thermostat in also regulates the rate at which the coolant circulates through the radiator.
Without any thermostat, the coolant would circulate too fast through the radiator so as to not allow adequate heat transfer into the atmosphere.
Without any thermostat, the coolant would circulate too fast through the radiator so as to not allow adequate heat transfer into the atmosphere.
Drifting
Joined: Jun 2005
Posts: 1,824
Likes: 1
From: Middleboro Massachusetts
You can test the thermostat by throwing it into a pot of boiling water to see if it opens properly. Check the oil for coolant, and the exhaust for a steamy appearence. Did you flush the radiator when you changed coolant? How is the coolant level in the resivoir? Did you use the orange coolant? You may have air in the sytem as stated above. It may be the water pump itself. There is alot to look for for sure.
Good luck and hope you find the problem.
Good luck and hope you find the problem.
