How hot is too hot
Thread Starter
Race Director
Joined: Sep 2003
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From: Database Error Indiana
How hot is too hot
Rebuilt my L98 about a week ago. Bumped up the compression with flat top pistons and topped it off with a Miniram. Now it is running hot About 210* on the highway with AC on. That I can deal with, but it got to 235* several times in town with a bit of idling in traffic, but not that much. It is 92* F here but it has never gotten that hot before.
Any ideas ? I am open to any and all. How hot does it take to hurt the motor ? I would hate to blow that 20 year old radiator apart. Vette owner, since 1980 and never had this problem.
Any ideas ? I am open to any and all. How hot does it take to hurt the motor ? I would hate to blow that 20 year old radiator apart. Vette owner, since 1980 and never had this problem.
Le Mans Master
Joined: Feb 2005
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From: The Motor City
Does the temp come down after it peaks, or does it just stay at that temp? Are these scanner numbers or dash?
Intermediate
Joined: Apr 2007
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Running hot
I'm sure that everyone will jump on this reply but my 91 runs pretty cool on a 90 degree day with the AC on. It's completly stock. I jumped the intake heating hose to bypass the throttle body. The thermostat is removed during the summer months and the radiator cap gasket is cut with slots for zero pressure. I'm running about 5% antifreeze and one bottle of Water Wetter from Red Line. After the car is turned off, the overflow tank may dump some water, so I usually ad about a quart of water each Saturday. In the winter I run a 160 degree thermostat and 50% antifreez and a 10 LB pressure radiator cap. I live in New Jersey so you can use my info adjust to your location. Make sure your water system is flushed and clean.
Thread Starter
Race Director
Joined: Sep 2003
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From: Database Error Indiana
The datalog reads high also. Pretty sure it is not hurt yet. Fan comes on around 180* . Just burped it and drove it. Still got to 230* at idle. Stays there. Would maybe climb more but no point in pushing it.
Thread Starter
Race Director
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From: Database Error Indiana
I think the radiator is doing well. I pointed the laser thermometer at it and it was 160 when the dash said 220. I also tried turning on the heater. This did keep the temp from climbing.
I used GM L98 head gaskets. They have tiny cooling holes compared to Felpro. I did not like the looks but used them thinking there was maybe a reason for it.
I used GM L98 head gaskets. They have tiny cooling holes compared to Felpro. I did not like the looks but used them thinking there was maybe a reason for it.
Last edited by JackDidley; Jul 8, 2007 at 07:35 PM.
Le Mans Master
Joined: Feb 2005
Posts: 5,146
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From: The Motor City
which fan? I found when I tuned an 87 for a freind the temp wasn't going below 210*even though I lowered the fan temp. Realized it was controlling the little fan not the big fan on back of the rad. I then lowered the AC fan temp and now it stays around 185.
Thread Starter
Race Director
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From: Database Error Indiana
Race Director
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From: The Top of Utah
Originally Posted by Spankyellow
Any ideas ? I am open to any and all. How hot does it take to hurt the motor ? I would hate to blow that 20 year old radiator apart. Vette owner, since 1980 and never had this problem.
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Thread Starter
Race Director
Joined: Sep 2003
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From: Database Error Indiana
New, tight engines tend to run hotter than normal during break in. I would make sure the cooling system is freshly maintained, including cleaning in front of the radiator, and then just watch the temps to make sure it doesn't get TOO hot. As long as you have a good, functioning, radiator cap, the cooling system pressure won't go over the cap limit, 14 to 15 psi, regardless of how hot it gets. If that causes the radiator to blow, then it was too weak to begin with. Make sure your timing isn't retarded. Even a few extra degrees of advance may help. That 180° fan on temp only serves to waste gas and prematurely wear out your fan motor.
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RACE ON!!!
Race Director
Joined: Sep 2000
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From: The Top of Utah
SnowFLAKE2000 reincarnated??? NC Kid? NC Punk?
What does jumping on "the intake heating hose" accomplish?
Do you have ANY idea of the purpose of the thermostat? The pressure cap?
A sure recipe for disaster, if I ever saw one.
Now let's see how many threads THIS will spawn.
RACE ON!!!
Originally Posted by Mickey1539
I jumped the intake heating hose to bypass the throttle body.
Originally Posted by Mickey1539
The thermostat is removed during the summer months and the radiator cap gasket is cut with slots for zero pressure.
Originally Posted by Mickey1539
After the car is turned off, the overflow tank may dump some water, so I usually ad about a quart of water each Saturday. In the winter I run a 160 degree thermostat and 50% antifreez and a 10 LB pressure radiator cap.
Now let's see how many threads THIS will spawn.
RACE ON!!!
Thread Starter
Race Director
Joined: Sep 2003
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From: Database Error Indiana
Just to be clear, the Miniram requires removal of the water passage in the throttle body. Antifreeze is 25%. I did install a new 180* failsafe stat.
Now I have to go mow for an hour.
Now I have to go mow for an hour.
Drifting
Joined: Apr 2007
Posts: 1,339
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From: port charlotte fl
This is such a repetitive subject and I'm sure,without offending anyone,that advice changes. I believe you have made those little explosions hotter with your mods and the temps are going to increase.Having said that 210 highway with a/c on in 92 ambient is perfectly acceptable. As is 235 in town(if the a/c was on). I've read posts from guys here that say they run highway a/c on at 200 mph and it never goes above 185 .Bull@#$%^. Anything over 180 with previous cars,boats,planes used to scare the crap out of me.Then you are told vettes are built to run hot to reach the emmissions standards. When mine gets to 220 the heater goes on!!!!!
Drifting
Joined: Apr 2007
Posts: 1,339
Likes: 2
From: port charlotte fl
SnowFLAKE2000 reincarnated??? NC Kid? NC Punk?
What does jumping on "the intake heating hose" accomplish?
Do you have ANY idea of the purpose of the thermostat? The pressure cap?
A sure recipe for disaster, if I ever saw one.
Now let's see how many threads THIS will spawn.
RACE ON!!!
What does jumping on "the intake heating hose" accomplish?
Do you have ANY idea of the purpose of the thermostat? The pressure cap?
A sure recipe for disaster, if I ever saw one.
Now let's see how many threads THIS will spawn.
RACE ON!!!
7th Gear
Joined: Jul 2007
Posts: 7
Likes: 0
From: Sterling Heights MI
So it looks like an agreement that somewhere around 220 is acceptable? I just replaced an intake gasket on my C4 and my operating temp has risen from 170 to 200 (225 oil temp) while on the highway. Is there no concerns with that?
Race Director
Joined: Oct 2005
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
The pressure is what raises the boiling point, so it won't dump water when shut off. Then you wouldn't have to add coolant to it every Saturday. The factory engineers are not as dumb as some people think they are.
Advanced
Joined: Jul 2006
Posts: 53
Likes: 0
From: las vegas nv
not trying to cause truble here..however my understanding is that a thermostat is pretty important..
it keeps coolant in the radiator long enuff to let it cool off..if you have no thermostat it free flows and water cant stay in the radiator long enuff to cool down..
thus leading to overheating.
if no thermostat is a viable option and im mistaken id like to learn more.
Bret
in the kiln called las vegas
it keeps coolant in the radiator long enuff to let it cool off..if you have no thermostat it free flows and water cant stay in the radiator long enuff to cool down..
thus leading to overheating.
if no thermostat is a viable option and im mistaken id like to learn more.
Bret
in the kiln called las vegas
Race Director
Joined: Oct 2005
Posts: 11,772
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
not trying to cause truble here..however my understanding is that a thermostat is pretty important..
it keeps coolant in the radiator long enuff to let it cool off..if you have no thermostat it free flows and water cant stay in the radiator long enuff to cool down..
thus leading to overheating.
if no thermostat is a viable option and im mistaken id like to learn more.
Bret
in the kiln called las vegas
it keeps coolant in the radiator long enuff to let it cool off..if you have no thermostat it free flows and water cant stay in the radiator long enuff to cool down..
thus leading to overheating.
if no thermostat is a viable option and im mistaken id like to learn more.
Bret
in the kiln called las vegas
No, you understand it correctly
It also allows your engine to reach proper operating temps. quicker.
Drifting
Joined: Oct 2006
Posts: 1,934
Likes: 3
From: Citrus Heights California
Personally I consider 235*F too hot. You might find some good information on these websites. I installed a Dewitt's radiator and did some mods to make the fan come on earlier. It helped a great deal.
http://gmtips.com/3rd-degree/dox/tips/cool/cool.htm
http://www.racerpartswholesale.com/redtech3.htm
http://gmtips.com/3rd-degree/dox/tips/cool/cool.htm
http://www.racerpartswholesale.com/redtech3.htm
Thread Starter
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
This is such a repetitive subject and I'm sure,without offending anyone,that advice changes. I believe you have made those little explosions hotter with your mods and the temps are going to increase.Having said that 210 highway with a/c on in 92 ambient is perfectly acceptable. As is 235 in town(if the a/c was on). I Anything over 180 with previous cars,boats,planes used to scare the crap out of me.Then you are told vettes are built to run hot to reach the emmissions standards. When mine gets to 220 the heater goes on!!!!!
I am one of those old guys that is more used to seeing 180* as normal. I totally agree that the increased compression has made those little explosions hotter. I feel this is a major factor in this. I am still wondering, if I changed to gaskets with bigger coolant holes would it go away ?? I would also like to hear from some Arizona guys, if they are actually running 235* on a daily basis.