LT4 Engine Overheating
Thread Starter
2nd Gear
Joined: Oct 2007
Posts: 2
Likes: 0
LT4 Engine Overheating
The engine in my 1996 LT4 Corvette is over heating in the range of 235 degrees to 240 degrees F. Two mechanics have told me they doubt that it's the thermostat. On suggested the Dex coolent used in these cars has a tendency to clog and obstruct the coolent flow and another told me he thinks there may be an air pocket in the cooling system. I had the engine burped and it still over heats. Any ideas what could be causing this? Could it be as easy as just installing a new thermostat? Has anyone had a similar problem? What is normal engine temp?
Race Director
Joined: Oct 2005
Posts: 11,772
Likes: 177
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
The engine in my 1996 LT4 Corvette is over heating in the range of 235 degrees to 240 degrees F. Two mechanics have told me they doubt that it's the thermostat. On suggested the Dex coolent used in these cars has a tendency to clog and obstruct the coolent flow and another told me he thinks there may be an air pocket in the cooling system. I had the engine burped and it still over heats. Any ideas what could be causing this? Could it be as easy as just installing a new thermostat? Has anyone had a similar problem? What is normal engine temp?
I don't believe the Dex coolent by itself causes clogs. Millions of cars have it in their system. But what WILL cause problems is mixing the Dex Cool with the old green stuff. They do not mix well, and will cause the clogs.
An air pocket is also possible, but you said you had it burped.
Next up, I would check for an airflow blockage. Crawl under the front nose, and look up into the airflow inlet to the radiator. These cars will suck up every type of trash, leaves, etc. there is.
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
It has to be burbed at op temp with t/stat open to get all the air out, hope it was done right. Turn on AC and see if fans are coming on and like Rolla said check for radiator blockage.
Advanced
Joined: Sep 2007
Posts: 50
Likes: 0
From: lexington nc
The deal with dexcool is if the system gets low, and air get in the system, it tends to solidify and get crusty, but it usually flushes out quite easily, have you had the cooling system pressure tested? including the radiator cap? if the system is leaking pressure the coolant will boil before it reaches coolant fan operating temp, any older car can have a suspect thermostat, but cooling system problems tend to be a real hands on diagnosis and very diifficult to talk someone through.
Team Owner
Joined: Mar 2001
Posts: 30,858
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Race Director
Joined: Oct 2005
Posts: 11,772
Likes: 177
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
I have two GM autos with over 100K miles, both using Dexcool. No problems at all.
My '96 Vette also has Dexcool in it, with around 80K miles. Again, no issues.
It's all in the maintenance.
A lot of the problems you hear about would have happened no matter what coolant the owner was using, just because they didn't do the proper maintenance on the car.
My '96 Vette also has Dexcool in it, with around 80K miles. Again, no issues.
It's all in the maintenance.
A lot of the problems you hear about would have happened no matter what coolant the owner was using, just because they didn't do the proper maintenance on the car.
Instructor
Joined: Jun 2003
Posts: 199
Likes: 0
From: National City MI
Are your fans coming on @ the overheat temp? If not run the A/C and see if it still overheats.
Like stated first check for radiator obstructions , but after all that I would go to the thermostat next. Just because someone says they doubt it is bad doesn't mean it isn't.
Like stated first check for radiator obstructions , but after all that I would go to the thermostat next. Just because someone says they doubt it is bad doesn't mean it isn't.
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
Le Mans Master
Joined: Aug 2004
Posts: 5,141
Likes: 7
From: Metairie Louisiana
Dexcool is bad! I would get rid of it. I flushed it completely out and replaced with the green stuff. No problems since.
Last edited by rickneworleansla; Nov 19, 2007 at 10:51 AM.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Its really great that your mechanics have such powers and abilities to just look at the engine and eliminate the thermostat, not to be sarcastic.
Take a quick look just to make sure there are no airflow restrictions.
When you turn on you’re A/C, on both fans should be running in low speed. With the outside temperatures this time a year you should not even get to the 215* mark. As long as the fans are running, that’s check #1. Under 70* I don’t even need fans to keep it under 200*.
A partially closed stat will cause that problem. The temperature will just keep climbing slowly depending on the health of the stat. Step #2 is the change the stat, cheep and easy before you escalate your repair process. And I know you will flush and add new coolant.
Do the basics before you go for the radiators and head gaskets.
I use dexcool in my chev 01 truck, I change it and no problems.
PS: Fill in your profile so we can see where you and the car lives.
Charge on
Take a quick look just to make sure there are no airflow restrictions.
When you turn on you’re A/C, on both fans should be running in low speed. With the outside temperatures this time a year you should not even get to the 215* mark. As long as the fans are running, that’s check #1. Under 70* I don’t even need fans to keep it under 200*.
A partially closed stat will cause that problem. The temperature will just keep climbing slowly depending on the health of the stat. Step #2 is the change the stat, cheep and easy before you escalate your repair process. And I know you will flush and add new coolant.
Do the basics before you go for the radiators and head gaskets.
I use dexcool in my chev 01 truck, I change it and no problems.
PS: Fill in your profile so we can see where you and the car lives.
Charge on
Race Director
Joined: Oct 2005
Posts: 11,772
Likes: 177
From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Le Mans Master
Joined: Aug 2004
Posts: 5,141
Likes: 7
From: Metairie Louisiana
Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
and I have 3 cars with dexcool. what is the problem ??
but to the first guy, put a 160 degree thermostat in there and see what happens. you may have to get it from hypertech, or other aftermarket source.
you need to eliminate 1 possibility at a time.
but to the first guy, put a 160 degree thermostat in there and see what happens. you may have to get it from hypertech, or other aftermarket source.
you need to eliminate 1 possibility at a time.
Le Mans Master
Joined: Aug 2004
Posts: 5,141
Likes: 7
From: Metairie Louisiana
