Overheating is an Understatement
Instructor
Joined: Aug 2001
Posts: 145
Likes: 1
From: Crown Point IN
Entrapped Air
The components you listed should have no problem keeping your engine running at the correct operating temperature. I suspect either blockage or air trapped in the cylinder heads (perhaps elsewhere). If the coolant tank is below any other part of the cooling system (radiator, cylinder heads, etc.) you will not be able to adequately fill the cooling system because the entry point is lower than the highest point in the system. I'll exaggerate to make my point - suppose your coolant tank was located just above the starter. You remove the pressure cap and try to add coolant. How are you going to make the coolant reach areas HIGHER than the coolant tank opening?
If this is the case, try filling through the upper radiator hose.
If this is the case, try filling through the upper radiator hose.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 162
Likes: 3
From: Denver CO
Thread Starter
Instructor
Joined: Dec 2009
Posts: 162
Likes: 3
From: Denver CO
The components you listed should have no problem keeping your engine running at the correct operating temperature. I suspect either blockage or air trapped in the cylinder heads (perhaps elsewhere). If the coolant tank is below any other part of the cooling system (radiator, cylinder heads, etc.) you will not be able to adequately fill the cooling system because the entry point is lower than the highest point in the system. I'll exaggerate to make my point - suppose your coolant tank was located just above the starter. You remove the pressure cap and try to add coolant. How are you going to make the coolant reach areas HIGHER than the coolant tank opening?
If this is the case, try filling through the upper radiator hose.
If this is the case, try filling through the upper radiator hose.
Burning Brakes
Joined: Sep 2001
Posts: 1,193
Likes: 194
From: East Coast
I’m running a numbers matching rebuilt 327/365hp motor in my ’64 coupe that is consistently overheating. Heading out on a drive I start with a 5 min drive to the highway and cruise at 60 mph. 15 min after that the needle climbs over 210 deg. This isn’t an issue of simply running hot, because it will continue over 210 if I don’t stop and it’s hard to completely enjoy a car that has a 20 min driving range. The temp grows consistently and only once did I let it go over 210 deg to puking (240+). That was a mistake I’ll only make once so to protect this motor.
I have gone through all the FAQ and Sticky threads on this forum and am at a dead end. References are listed in the links at the bottom for what I read through. The most helpful was John Hinckley’s article titled “Early Corvette Cooling”.
To follow Mr. Hinckley’s checklist:
Coolant – 50/50 mix with Water Wetter
Radiator – 6 years old aluminum Griffin that has been flushed regularly, is clean of debris, and has good flow. 20 deg of cooling when idling in garage (180 top, 160 bottom)
Expansion Tank – Filled exactly half way to the “Fill Cold” line
Water Pump – High flow replacement
Thermostat – New, tested 160 deg. (I know 160 vs. 180 is irrelevant)
Radiator Cap – 16# (13# used with same result)
Lower Radiator Hose – New and reinforced
Fan Shroud and Seals – All stock and accounted for
Fan and Clutch – Clutch fan working properly. Replaced with solid racing fan and got same result. Half-in/half-out
Temperature Gauge and Sending Unit – Verified accurate with IR gun
Ignition Timing – Total timing set to 34 deg results with a base timing of 12 deg. Less advanced timing provided the same result in temp.
Engine Bore – 4.06” diameter
I’ve had the car for two weeks and would like to “watch the scenery while cruising instead of the temperature gauge” so any input is much appreciated.
Thanks,
John
Reference material:
Overheating / Cooling FAQ - http://forums.corvetteforum.com/1558302870-post3.html
Barry and Linda’s Vette Tech Section - http://lbfun.com/Corvette/Tech/vettetech.html
Still boiling hot but there is light. - http://forums.corvetteforum.com/c1-a...post1561445673
66 corvette over heating - http://forums.corvetteforum.com/c1-a...r-heating.html
I have gone through all the FAQ and Sticky threads on this forum and am at a dead end. References are listed in the links at the bottom for what I read through. The most helpful was John Hinckley’s article titled “Early Corvette Cooling”.
To follow Mr. Hinckley’s checklist:
Coolant – 50/50 mix with Water Wetter
Radiator – 6 years old aluminum Griffin that has been flushed regularly, is clean of debris, and has good flow. 20 deg of cooling when idling in garage (180 top, 160 bottom)
Expansion Tank – Filled exactly half way to the “Fill Cold” line
Water Pump – High flow replacement
Thermostat – New, tested 160 deg. (I know 160 vs. 180 is irrelevant)
Radiator Cap – 16# (13# used with same result)
Lower Radiator Hose – New and reinforced
Fan Shroud and Seals – All stock and accounted for
Fan and Clutch – Clutch fan working properly. Replaced with solid racing fan and got same result. Half-in/half-out
Temperature Gauge and Sending Unit – Verified accurate with IR gun
Ignition Timing – Total timing set to 34 deg results with a base timing of 12 deg. Less advanced timing provided the same result in temp.
Engine Bore – 4.06” diameter
I’ve had the car for two weeks and would like to “watch the scenery while cruising instead of the temperature gauge” so any input is much appreciated.
Thanks,
John
Reference material:
Overheating / Cooling FAQ - http://forums.corvetteforum.com/1558302870-post3.html
Barry and Linda’s Vette Tech Section - http://lbfun.com/Corvette/Tech/vettetech.html
Still boiling hot but there is light. - http://forums.corvetteforum.com/c1-a...post1561445673
66 corvette over heating - http://forums.corvetteforum.com/c1-a...r-heating.html
This is a DA question;
Did you replace the head gasket and some how install it backwards and cover the water outlets?
Thread Starter
Instructor
Joined: Dec 2009
Posts: 162
Likes: 3
From: Denver CO
Thread Starter
Instructor
Joined: Dec 2009
Posts: 162
Likes: 3
From: Denver CO
Here are a couple sheets from the build:
Le Mans Master
Joined: Dec 2007
Posts: 8,000
Likes: 659
From: Puget Sound
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
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
Le Mans Master
Joined: Feb 2008
Posts: 6,528
Likes: 1,939
From: Folsom CA
Fill from the Thermostat housing, yes I know this means it has to be unbolted from the manifold. Fel Pro makes a Perma Dry plus gasket for the thermostat that is re useable and does not need any sealant.
Part # 35562T it uses a solid body with rubberized silicone so it seals more like modern gaskets. ( Will not pass judging if this car is NCRS points car ) This does allow you to quickly remove the two bolts lift up the thermostat, check your fluid level and re install with no clean up or wasted time.
If your fluid level is not at the thermostat when you open it up you have trapped air. The location of the Corvette overflow tank is a cause of trapped air because it is located low in the fender, you can't fill a Corvette completely from the coolant tank. You do not have to drain and refill, just open the thermostat and burp any trapped air and re fill directly into the thermostat housing hole, thermostat removed, with the car parked front end up. Most driveways have enough grade to do this.
This is not new science, modern cars have burp valves positioned at the highest point to get air out of the systems, some have multiple burp points. You could always drill and tap a burp valve into the top of the thermostat housing, it would sure make this job easy. ( would not please the points judge ).
When you fill the block do it where it is quiet and listen as you fill, you will hear air escaping, stop frequently and let the air escape before continuing your fill to avoid trapping air in the system.
Hope this helps.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 162
Likes: 3
From: Denver CO
Thread Starter
Instructor
Joined: Dec 2009
Posts: 162
Likes: 3
From: Denver CO
Fill from the Thermostat housing, yes I know this means it has to be unbolted from the manifold. Fel Pro makes a Perma Dry plus gasket for the thermostat that is re useable and does not need any sealant.
Part # 35562T it uses a solid body with rubberized silicone so it seals more like modern gaskets. ( Will not pass judging if this car is NCRS points car ) This does allow you to quickly remove the two bolts lift up the thermostat, check your fluid level and re install with no clean up or wasted time.
If your fluid level is not at the thermostat when you open it up you have trapped air. The location of the Corvette overflow tank is a cause of trapped air because it is located low in the fender, you can't fill a Corvette completely from the coolant tank. You do not have to drain and refill, just open the thermostat and burp any trapped air and re fill directly into the thermostat housing hole, thermostat removed, with the car parked front end up.
Part # 35562T it uses a solid body with rubberized silicone so it seals more like modern gaskets. ( Will not pass judging if this car is NCRS points car ) This does allow you to quickly remove the two bolts lift up the thermostat, check your fluid level and re install with no clean up or wasted time.
If your fluid level is not at the thermostat when you open it up you have trapped air. The location of the Corvette overflow tank is a cause of trapped air because it is located low in the fender, you can't fill a Corvette completely from the coolant tank. You do not have to drain and refill, just open the thermostat and burp any trapped air and re fill directly into the thermostat housing hole, thermostat removed, with the car parked front end up.
Le Mans Master
Joined: Feb 2008
Posts: 6,528
Likes: 1,939
From: Folsom CA
You may have already done this and have a full engine but it sure won't hurt to know. I really hope you get it running so you can start to drive and enjoy. ( the dirty secret is many on this forum enjoy the tinkering it takes to keep one of these old machines running otherwise we could just buy a new car and turn the key )
Thread Starter
Instructor
Joined: Dec 2009
Posts: 162
Likes: 3
From: Denver CO
You may have already done this and have a full engine but it sure won't hurt to know. I really hope you get it running so you can start to drive and enjoy. ( the dirty secret is many on this forum enjoy the tinkering it takes to keep one of these old machines running otherwise we could just buy a new car and turn the key )
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
You can bleed off any trapped air by loosening the thermostat housing.
Le Mans Master
Joined: Feb 2008
Posts: 6,528
Likes: 1,939
From: Folsom CA
I think loosening the T stat housing is another way of skinning the same horse, should work just fine. Watch the escaping air till you get fluid with no air bubbles and your good to go. I like that re useable gasket for this type work. It saves tearing a Paper or fiber design or needing sealer. I replaced the water pump on my wifes 530i Straight 6 cyl, it had a purge at the front of the engine and another on the top of the radiator, made it very easy to purge the air. I fill them carefully and was surprised how much air was still trapped on start up.
Le Mans Master
Joined: Feb 2008
Posts: 6,528
Likes: 1,939
From: Folsom CA
The head piston Engineer for Sealed Power built a 496 for his pickup back in 2001, he tows his 70 Buick to the race track with the pickup, the pickup will run a high 13 second qtr mile with this new 496.
His Piston to wall clearance is .0009, under one thou clearance.
He built this engine with Hypereutectics not forged but it works, to tow and to race when he wants to. He did this because he knows it works in a perfect engine.
Modern manufacturing of engines has piston installs of .0006 in production engines with Hyper pistons and skirt coatings.
His Piston to wall clearance is .0009, under one thou clearance.
He built this engine with Hypereutectics not forged but it works, to tow and to race when he wants to. He did this because he knows it works in a perfect engine.
Modern manufacturing of engines has piston installs of .0006 in production engines with Hyper pistons and skirt coatings.
Race Director
Joined: Jul 2002
Posts: 11,593
Likes: 173
From: Clayton NC
After reading through the thread.. First to everyone that thinks the stock pumps that you can buy over the counter are just as good as the old pumps haven't taken the back off them.. The cast impeller moved water.. the stamped ones that you see now don't do as good as a job.
I don't think it's a pump problem regardless if it's a high flow pump. I have a Stewarts Stage II pump and it keeps the car cooled even on the hottest days.
I do agree that someone else should take a look at the car and you have one hell of a engine guy in your backyard there in Denver. He's here on the forum and his name is Lars.
Hitch
I don't think it's a pump problem regardless if it's a high flow pump. I have a Stewarts Stage II pump and it keeps the car cooled even on the hottest days.
I do agree that someone else should take a look at the car and you have one hell of a engine guy in your backyard there in Denver. He's here on the forum and his name is Lars.
Hitch