Unusual heating problem
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Joined: Apr 2001
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From: Tampa, Florida, USA fl
Unusual heating problem
Recently I had my left fan motor replaced, my radiator cored (cleaned) and a 160 degree thermostat installed. The car runs fine around town. Recently, however, at highway speeds, the temp goes up to 120 when it used to hover around 200! I am at a loss. Could I have a bad thermostat?
Racer
Joined: Aug 2004
Posts: 379
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From: Buffalo Grove IL
Whoops, answered this in your Scan & Tune section post. What is your coolant temp when driving around town & stuck in traffic? 120 could be caused by a thermostat stuck open, but that seems really low--my car used to hang around 150 on the highway when the thermostat was stuck open.
Ben
Ben
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From: Tampa, Florida, USA fl
Unusal heating
Stuck in traffic can go as high as 228. This is a new problem. Normally the temp drops at highway speeds. I topped off my coolant to be sure -no visable leaks.
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
A 160 degree stat means that the stat is designed to be fully open at that water temerature allowing coolant to circulate. A 120 degree reading sounds as though the stat is stuck in a fully open position so the coolant is always circulating.
At 228 degrees, the secondary fan should be just about ready to turn on (it's controlled by the temp sensor) and will shut off when the temps drop by around 40 degrees. At freeway cruise speeds the fans should not normally come on as airflow should keep the coolant temps below where the fans should be coming on.
Are you seeing 120 on the display or 220 ?
At 228 degrees, the secondary fan should be just about ready to turn on (it's controlled by the temp sensor) and will shut off when the temps drop by around 40 degrees. At freeway cruise speeds the fans should not normally come on as airflow should keep the coolant temps below where the fans should be coming on.
Are you seeing 120 on the display or 220 ?
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
A stuck 'stat could be a possibility. Another possibility is air in the system. Did the system get filled properly? There are two bleed valves that need to be opened when refilling the cooling system. Not having these valves open may have caused air pockets to form resulting in higher temps.
Did you replace the upper and lower hoses? If not, it's possible that one of these hoses are collapsing and causing a reduction in flow.
If the radiator was pulled out for cleaning, then the intake area should be clean. But check the front of the A/C condensor for anything that may be blocking the flow of air. You may have picked up some leaves, plastic bags, papers, small animals, Honda's or who knows what
Did you replace the upper and lower hoses? If not, it's possible that one of these hoses are collapsing and causing a reduction in flow.
If the radiator was pulled out for cleaning, then the intake area should be clean. But check the front of the A/C condensor for anything that may be blocking the flow of air. You may have picked up some leaves, plastic bags, papers, small animals, Honda's or who knows what
Burning Brakes
Joined: Dec 2003
Posts: 770
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From: Madison Mississippi
Burp your baby!! wait until it cools and squeeze the top radiator hose until water dribbles out and shut the valve, repeat until you get all the air out. I did find rocks, plastic bags, and sticks up in front of my radiator too. Corvettes actually clean the environment as you drive around picking up trash
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Joined: Apr 2001
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From: Tampa, Florida, USA fl
I did check to see if the space between a/c and radiator was clean- This came on suddenly- so I suspect the thermostat- I will check the system for air bubbles 1st- Thanks for the help.
Team Owner
Joined: Dec 1999
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Check the coolant level in the expansion tank; remove the pressure cap to check for coolant level . Chances are the tank is very low or empty. Fill the tank to just below the cap sealing ring. Start the motor and let it get to operating temp. If there is coolant in the tank, when the thermostat opens you may see a sudden drop in the coolant level.
If the level does drop, run the motor at 1500 or so RPM and add a 50-50 mix of coolant until the level is maintained at just below the sealing ring. Replace the cap and let the engine idle. Make sure the overflow tank is filled to the HOT mark. Do a test drive to see what the temps are.
The service manual specifies that you should not attempt any WOT conditions until after 3 cycles of coolant temps from cold to hot to cold. This helps to work out any air pockets before you hit the gas hard.
If the level does drop, run the motor at 1500 or so RPM and add a 50-50 mix of coolant until the level is maintained at just below the sealing ring. Replace the cap and let the engine idle. Make sure the overflow tank is filled to the HOT mark. Do a test drive to see what the temps are.
The service manual specifies that you should not attempt any WOT conditions until after 3 cycles of coolant temps from cold to hot to cold. This helps to work out any air pockets before you hit the gas hard.
