What am I overlooking? Overheating issue
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
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What am I overlooking? Overheating issue
I have an 82 with 28K miles. I drove it from NJ to FL with no mechanical issues. I've been in the process of doing some resto work as the car sat neglected for a number of years.
I have replaced the radiator with a new 4 row, a new t-stat, new hoses, new temp sensor (the one in the left cyl head) and all new belts. The fan and fan clutch appear to be OK.
My issue is at idle the engine gets hot (temp over 200* per the gauge) but the radiator and coolant inside remain ice cold. I do not see any circulation in the radiator and once the engine comes up to temp the coolant rises to the top of the neck and "burps" out. I have the water pump out now but don't feel any bearing slop and the impeller appears to move as it should.
Am I overlooking something obvious? It's been a while since I've had a car without a serpentine belt and belt driven fan. I sold my last C3 in 1992. I've gone through a C4 and a C5 since and now drive a C6.
Any and all suggestions will be greatly appreciated. This is the last thing to get fixed to make it drivable again.
I have replaced the radiator with a new 4 row, a new t-stat, new hoses, new temp sensor (the one in the left cyl head) and all new belts. The fan and fan clutch appear to be OK.
My issue is at idle the engine gets hot (temp over 200* per the gauge) but the radiator and coolant inside remain ice cold. I do not see any circulation in the radiator and once the engine comes up to temp the coolant rises to the top of the neck and "burps" out. I have the water pump out now but don't feel any bearing slop and the impeller appears to move as it should.
Am I overlooking something obvious? It's been a while since I've had a car without a serpentine belt and belt driven fan. I sold my last C3 in 1992. I've gone through a C4 and a C5 since and now drive a C6.
Any and all suggestions will be greatly appreciated. This is the last thing to get fixed to make it drivable again.
Racer
Joined: Sep 2007
Posts: 295
Likes: 2
From: Concordia KS
It sounds like it has air in the sys. You can remove the thermostat and run without it to make sure you have all the air out, or drill 1 or two 1/8 holes in the thermostat to allow the air to bleed out. If it works fine after running it without the thermostat then I would try a new thermostat. You could have one that is not opening.
Racer
Joined: Feb 2007
Posts: 345
Likes: 0
From: Sebago Lake Maine
St. Jude Donor '09
Could be an air bubble in the top of the block. Prevents T-stat from opening. I had the same problem when I put a new aluminum radiator in. Someone on the forum suggested taking the thermostat out and drilling an 1/8 in. in the flat part of it on the edge. It lets air purge out through the upper hose but not enough coolant to affect the thermostat. I'm no expert but it worked great when I did it.
4th Gear
Joined: Dec 2010
Posts: 4
Likes: 0
you may want to check and see that you have the correct rotation waterpump, most serpentine belt system water pumps rotate backward compared to v belt style water pumps. If its spinning the wrong direction, it will not circulate the coolant correctly.
Melting Slicks
Joined: Mar 2009
Posts: 3,126
Likes: 15
What temp. thermostat are you using? With radiator cap off and thermostat open you should see coolant coming through the upper radiator tubes from drivers side to pass. side. Poss. air lock but I doubt it. Sounds more like thermostat is not opening. Burping is normal if radiator is full to top when cold, as water heats up it expands. Leave coolant a little low, about 3 or 4 inches below cap and leave cap off to test. When thermostat opens, water just below cap should start to move and upper hose will get hot. mike...
Last edited by mds3013; Dec 5, 2010 at 09:28 PM.
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
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I'm on my second new t-stat and both were installed correctly. I shut it down before the electric fan came on. The original t-stat was stuck in the open position and that would explain why it didn't overheat when I drove it down from NJ.
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Thread Starter
Race Director
Joined: Jul 2000
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
2021 C6 of the Year Winner - Modified
2020 C7 of the Year Finalist -- Modified
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I'll be installing a new water pump tomorrow. Drive belts are good with no slip. If it's the t-stat then I'm on a roll of bad luck. I'm on my second new one.
Thread Starter
Race Director
Joined: Jul 2000
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
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2021 C6 of the Year Winner - Modified
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What temp. thermostat are you using? With radiator cap off and thermostat open you should see coolant coming through the upper radiator tubes from drivers side to pass. side. Poss. air lock but I doubt it. Sounds more like thermostat is not opening. Burping is normal if radiator is full to top when cold, as water heats up it expands. Leave coolant a little low, about 3 or 4 inches below cap and leave cap off to test. When thermostat opens, water just below cap should start to move and upper hose will get hot. mike...
Thread Starter
Race Director
Joined: Jul 2000
Posts: 16,510
Likes: 2,400
From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
2021 C6 of the Year Winner - Modified
2020 C7 of the Year Finalist -- Modified
2020 C6 of the Year Finalist - Modified
The water pump I removed was the original so it should have had the correct rotation.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Even if you have a 180 stat installed, the engine will continue to heat up until the fans come on to cool the radiator down. If the temp switch for the fan doesn't come on till 200, that could be your problem. With a 180 stat, you want a 185 or 190 fan temp switch.
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
I have been working on an 82 recently. I went to fill up the cooling system and filled it through the radiator. I got the radiator filled but it would not go into the block. I thought this is strange and thought maybe a bad WP. It was brand new also. Then thinking the newer systems are much more air tight than my 72 I took off the coolant line right at the water bypass valve. This I could see was the highest point in the cooling system. As soon as the line came off I heard a big woosh of air from that line and the coolant in the radiator dropped immediatly. I stuck a funnel in the coolant line that went from the bypass valve to the back of the intake. I filled the system this way and could see it rising in the radiator. Waited until it started to spill from the radiator. Capped that and filled until I had fluid at the hose. This got all the air out and it works fine now.
I also just got it burping before I did this trick. Maybe just air locked.
I also just got it burping before I did this trick. Maybe just air locked.
Race Director
Joined: Jul 2001
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'73 and up Corvettes have sealed systems. Fill the rad to the top. Put on the cap. Fill the coolant recovery tank to the max cold mark. Start the engine- the air will burp out as it comes up to temp. Check the tank a few more times after driving the car and refill as required. Done.
Thread Starter
Race Director
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
2021 C6 of the Year Winner - Modified
2020 C7 of the Year Finalist -- Modified
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It's supposed to do that- you're trying to fix something that's not broken.
'73 and up Corvettes have sealed systems. Fill the rad to the top. Put on the cap. Fill the coolant recovery tank to the max cold mark. Start the engine- the air will burp out as it comes up to temp. Check the tank a few more times after driving the car and refill as required. Done.
'73 and up Corvettes have sealed systems. Fill the rad to the top. Put on the cap. Fill the coolant recovery tank to the max cold mark. Start the engine- the air will burp out as it comes up to temp. Check the tank a few more times after driving the car and refill as required. Done.
I've worked on my own cars since my first car back in 1974. This one has me baffled. Am I chasing a ghost?
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
If the engine temp is hot but the radiator is cold, then you obviously have a thermostat issue. Get a good Stewart Warner race stat that has the 3 3/16" holes drilled in it and put it in. The holes help burp the air out as well as let some coolant bypass. Most new thermostats are Chinese junk these days.
If you really want to test the theory, just leave the stat out and run it...you will see it runs very cool.....then put your stat back in after the test.
If you really want to test the theory, just leave the stat out and run it...you will see it runs very cool.....then put your stat back in after the test.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
I did that initially. The problem is the engine gets hot but the radiator stays cold. The gauge will climb past the 200* mark and will continue to climb if I don't shut it down. I changed one temp sensor (the one in the left head) as the gauge would initially peg full hot and then drop back below 200 and then sweep back and forth from full peg to below 200. After I changed the sensor the gauge starts off on a normal climb, rests near 200 and then starts climbing hotter.
I've worked on my own cars since my first car back in 1974. This one has me baffled. Am I chasing a ghost?
I've worked on my own cars since my first car back in 1974. This one has me baffled. Am I chasing a ghost?
If, after one of these overtemp excursions and you let the engine cool, is the rad full to the brim and there's still coolant in the recovery tank?
If so it's a flow issue. If not, there's still air in the system.
Thread Starter
Race Director
Joined: Jul 2000
Posts: 16,510
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From: Out Where the Buses Don't Run, Eglin AFB/ Niceville FL
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2022 Corvette of the Year Finalist -- Modified
2021 C6 of the Year Winner - Modified
2020 C7 of the Year Finalist -- Modified
2020 C6 of the Year Finalist - Modified
Thanks to everyone for their inputs and I'll keep you posted on what happens. Any more suggestions will be greatly appreciated as well.
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
The best way I've found to burp air out is to jack the right front of the car up, so the radiator cap is the highest point in the system, then run it with the cap off, and add coolant as needed. When mine had an air bubble in it, it did just what you said, the temp gauge quickly rose to higher than I was comfortable with, and just as you said, the radiator was ice cold. Getting the air out fixed the problem.