Overheating after alum radiator install
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
Overheating after alum radiator install
My 1981 Corvette was losing coolant, so I figured it was the radiator and replaced the radiator with a 3 core aluminum radiator. Even when the stock radiator was half full of coolant the car generally would not over heat. Now just following the alum radiator install, the car will heat up to the thermostat temp rating (thermostat then opens) and stay at 190 deg, while idling. The problem is when I start driving it, the temp always zooms up to about 230 deg and even beyond sometimes. I brought the car back to the driveway and let it idle, and looked under the car for leaks. No leaks. The radiator is full, but actually it seems to be still losing water somewhere. Still, I am scratching my head wondering why it overheats so quickly, I ran it around all over the place with the stock radiator half full and it usually didn't overheat. Bear in mind I'm in Houston and the outside temp is 90 deg + but I would still think that an 3 core alum radiator with dual electric fans on all the time, the temp should stay rock solid on 190 deg. Anyone have any ideas on what is causing this?
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
With my alum rad if I give just a bit of throttle to get the water pump spinning faster the temperature will drop quite a bit, just standing still.
I'd imagine you have an air bubble, when you filled the system was the front end raised? Did you have the heater running on full hot?
I'd imagine you have an air bubble, when you filled the system was the front end raised? Did you have the heater running on full hot?
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
With my alum rad if I give just a bit of throttle to get the water pump spinning faster the temperature will drop quite a bit, just standing still.
I'd imagine you have an air bubble, when you filled the system was the front end raised? Did you have the heater running on full hot?
I'd imagine you have an air bubble, when you filled the system was the front end raised? Did you have the heater running on full hot?
Drifting
Joined: Jul 2002
Posts: 1,995
Likes: 110
From: Garland Texas
Most likely you have 624 heads on the engine. These are prone to cracking just by staring at them. They always crack between the seats and only shows up when the engine is hot. Pressure testing the radiator won't show the problem unless you fill a cylinder and hydro the motor.
If you have plenty of anti-freeze in the engine your exhaust should have a sweet smell to it. You can also run the engine with the cap off. See if the radiator continues to blow bubbles in the coolant. But be very careful. If it burps you can get seriously burnt.
You can also pull the plugs and look for one that have been steam cleaned.
If you do pressurize the radiator do it with the engine running. Watch the pressure gauge. See if it keeps building pressure. If the crack is large enough you can force a misfire in the bad cylinder. Be sure to release the pressure before turning off the engine.
Mike
If you have plenty of anti-freeze in the engine your exhaust should have a sweet smell to it. You can also run the engine with the cap off. See if the radiator continues to blow bubbles in the coolant. But be very careful. If it burps you can get seriously burnt.
You can also pull the plugs and look for one that have been steam cleaned.
If you do pressurize the radiator do it with the engine running. Watch the pressure gauge. See if it keeps building pressure. If the crack is large enough you can force a misfire in the bad cylinder. Be sure to release the pressure before turning off the engine.
Mike
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
Well there is coolant dribbling out of both sidepipes so I guess that answers that question. What I don't understand is that the motor has gotten way hotter than that, so those heads must have been cracked for some time now, which explains the reason why the radiator was always low on coolant, but the temps always stayed under control until I replaced the stock with the alum radiator. I guess the outside heat is just too much, seems like last summer during august I had the same problem. When the temps cooled down some it was not a problem. Guess its time for some new heads, might as well buy a cam too!
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
Getting any exhaust smell in the coolant? Put it in gear and torque it up after its warmed up with the brake on. Have someone look for coolant from the exhaust. Pull your plugs and look for any signs of rusting.
Just a few things to help make up your mind.
Could be the heads might need resurfaced.
Just a few things to help make up your mind.
Could be the heads might need resurfaced.
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
Looks like you have your answer.
http://www.dragzine.com/features/pri...eads-from-afr/
Cheap, too. For the cost of no more than 3 driver quality late C3s you could have an engine running these.
I really would like to see a review on these, especially in a 'vette.
http://www.dragzine.com/features/pri...eads-from-afr/
Cheap, too. For the cost of no more than 3 driver quality late C3s you could have an engine running these.
I really would like to see a review on these, especially in a 'vette.
Thread Starter
Drifting
Joined: Jun 2011
Posts: 1,704
Likes: 27
Looks like you have your answer.
http://www.dragzine.com/features/pri...eads-from-afr/
Cheap, too. For the cost of no more than 3 driver quality late C3s you could have an engine running these.
I really would like to see a review on these, especially in a 'vette.
http://www.dragzine.com/features/pri...eads-from-afr/
Cheap, too. For the cost of no more than 3 driver quality late C3s you could have an engine running these.
I really would like to see a review on these, especially in a 'vette.I would think a head that flows 400 cfm, I'd lose all kinds of torque midrange wise with my little turd of an engine. But there I go again thinking...