overheating issue
Thread Starter
Racer
Joined: Jun 2007
Posts: 459
Likes: 2
From: Hawaii
overheating issue
I own a 96 collector edition LT1 , the engine always peaks at 220 during highway driving, and after a long hard drive, it will shoot up to 230 at a light. I just replaced the Opti and brand new water pump and gave it a coolant flush. I know the cooling fans dont engage until 226+ degrees, the factory ECM settings are pathetic for a single core raditor. Does anybody know where I can find somebody or a online company that can reflash or reconfigure the ECM to run cooler??
The coolant system is 15 PSI or 16? cant find a 15 PSI cap....?????
The coolant system is 15 PSI or 16? cant find a 15 PSI cap....?????
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
15 psi cap mate 
Have you done a CO test on the coolant with the engine running? No good reason for it to be running that high.
Turning your fans on earlier wont help you one bit either, if youre going along the highway and its that warm, its got bugger all to do with fan on temps. If you want to put the fans on, putting the A/C on will put both fans on straight away.
The fan on temps is not your issue here.
Have you done a CO test on the coolant with the engine running? No good reason for it to be running that high.
Turning your fans on earlier wont help you one bit either, if youre going along the highway and its that warm, its got bugger all to do with fan on temps. If you want to put the fans on, putting the A/C on will put both fans on straight away.
The fan on temps is not your issue here.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
Those temps aren't seriously out of line. If 220° were too high, the fan would be programmed to come on by then. It is probably time for some maintenance. If you can't remember when the cooling system was flushed, last, that would be a good place to start. Then, pull the radiator, or at least the top half of the shroud and clean between the radiator and the condenser.
Either a 15# or 16# cap will do. One pound doesn't make a significant difference.
RACE ON!!!
Either a 15# or 16# cap will do. One pound doesn't make a significant difference.
RACE ON!!!
Race Director
Joined: Jan 2005
Posts: 10,641
Likes: 13
From: Slidell Louisiana
I own a 96 collector edition LT1 , the engine always peaks at 220 during highway driving, and after a long hard drive, it will shoot up to 230 at a light. I just replaced the Opti and brand new water pump and gave it a coolant flush. I know the cooling fans dont engage until 226+ degrees, the factory ECM settings are pathetic for a single core raditor. Does anybody know where I can find somebody or a online company that can reflash or reconfigure the ECM to run cooler??
The coolant system is 15 PSI or 16? cant find a 15 PSI cap....?????
The coolant system is 15 PSI or 16? cant find a 15 PSI cap....?????
Those temps aren't seriously out of line. If 220° were too high, the fan would be programmed to come on by then. It is probably time for some maintenance. If you can't remember when the cooling system was flushed, last, that would be a good place to start. Then, pull the radiator, or at least the top half of the shroud and clean between the radiator and the condenser.
Either a 15# or 16# cap will do. One pound doesn't make a significant difference.
RACE ON!!!
Either a 15# or 16# cap will do. One pound doesn't make a significant difference.
RACE ON!!!
I have to agree with CFI EFI this time.
Last edited by aboatguy; Jun 22, 2007 at 02:58 PM.
Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
Just have someone program your computer to make your primary fan kick in at 195 degrees. Simple. Jeez, I'm in Phoenix, AZ, and I seldom run more than 205 degrees (and it was 110 * today). Of course, I may be cheating because a have a Ron Davis radiator.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
195*F is too early to have the fan come on if youve got a 180*F stat in an LT1, way too early.
The GM service manual states in one section of book 1 that operating temp is 94*C or 201*F. My 94 will sit anywhere from 88*C up to 92*C when the car is moving, so if you set the fan on temp that low, they would probably be on all the time, and that wont help anything at all when youre cruising at 65mph down the highway.
You are cheating cause you have a Ron Davis radiator, but with a stock radiator setting the fans that low is too low.
The GM service manual states in one section of book 1 that operating temp is 94*C or 201*F. My 94 will sit anywhere from 88*C up to 92*C when the car is moving, so if you set the fan on temp that low, they would probably be on all the time, and that wont help anything at all when youre cruising at 65mph down the highway.
You are cheating cause you have a Ron Davis radiator, but with a stock radiator setting the fans that low is too low.
Melting Slicks
Joined: Dec 2004
Posts: 3,280
Likes: 50
From: Jacksonville, FL
St. Jude Donor '08 thru '25
If those are your highway crusing speed temps then I'm with the guys that say to look for junk in the rad, provided that you have kept up with cooling system maintenance. At anything over about 35 mph the air flow from car movement is way more than what the both fans can pull thru the rad....at least I think.
Do you have a screen covering the air intake above the air dam? If not, then you could have a collection of junk just like the picture. That will kill system effectiveness. Also any bent fins and small pebbles stuck in the fins will severely block air flow. The pebbles are a bear to get out....took me the better part of 4 hrs to do my rad and it almost came to the point of "It may be worth it to buy a new rad!"
JMHO
Tom
Do you have a screen covering the air intake above the air dam? If not, then you could have a collection of junk just like the picture. That will kill system effectiveness. Also any bent fins and small pebbles stuck in the fins will severely block air flow. The pebbles are a bear to get out....took me the better part of 4 hrs to do my rad and it almost came to the point of "It may be worth it to buy a new rad!"
JMHO
Tom
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