Running Hot
Thread Starter
Cruising
Joined: Aug 2006
Posts: 12
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From: Marysville Washington
Running Hot
I just got my Dad's '89 vette and when coming across the country it was running too hot, 225 f. So I stopped in a Chevy dealer in Nebraska. He did tests on the relays, etc and said it was the mother board. I drove home with the defrost A/C on, was the only setting for the fan to work. I notice there are many after market fan/thermostat products. Can I bypass the expensive mother board and run the fan with one of these after market products?
Matt
Matt
Le Mans Master
Joined: Jun 2006
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From: One day you're a Comet...the next day you're dust... Arkansas
Short answer is yes. It will be much easier if you have an aux. fan. See if there is a fan in front of the rad, if so, there should be a sensor switch between plugs 1 and 3 in the head on the drivers side. You can replace that sensor and turn on one or both fans from there. Please fill in your profile info, it will help answer some questions.
Race Director
Joined: Jun 2004
Posts: 13,924
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From: WI
I removed the aux. fan on mine and the temp. dropped as there was more flow on the radiator. A fan is not going to help at cruising speed. You probably need to clean out the space between the radiator of debris. Also, is the coolant old?
Thread Starter
Cruising
Joined: Aug 2006
Posts: 12
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From: Marysville Washington
The coolant was just changed. I will clean 'er up and try a after market fan. By the way, at highway speeds and the defrost A/C on it runs about 190F.
Thanks for your help.
Matt
Thanks for your help.
Matt
Last edited by MattElle; Sep 6, 2006 at 12:05 PM.
Thread Starter
Cruising
Joined: Aug 2006
Posts: 12
Likes: 0
From: Marysville Washington
Race Director
Joined: Jun 2004
Posts: 13,924
Likes: 700
From: WI
190° is a good temp. on the highway. Was the thermostat changed for a lower temp.? Stock is 195° so the car is running cooler then it did new. That kit would change the front aux. fan to come on sooner. On my car the main fan, controlled by the ECM is enough.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
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From: seattle WA
That switch will work.....but I think one with the on at 200 and off at 185 is less demanding on the fans...that's what I run on my 87 with a 180 thermo.....I rarely ever see over 210 in 90 degrees stop and go, and usually cruise around 180-185.
Race Director
Joined: Sep 2000
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From: The Top of Utah
Originally Posted by MattElle
I just got my Dad's '89 vette and when coming across the country it was running too hot, 225 f. So I stopped in a Chevy dealer in Nebraska. He did tests on the relays, etc and said it was the mother board.
Matt
Matt
RACE ON!!!
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Thread Starter
Cruising
Joined: Aug 2006
Posts: 12
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From: Marysville Washington
I appreciate everyone's input. The mechanic at the Chevy dealer said the mother board was showing a ground. He could not get the fan to come on. The only time it got hot was in traffic at slow speeds not at highway speed.
What is a hot temp for the L98?
Matt
What is a hot temp for the L98?
Matt
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by MattElle
I appreciate everyone's input. The mechanic at the Chevy dealer said the mother board was showing a ground. He could not get the fan to come on. The only time it got hot was in traffic at slow speeds not at highway speed.
What is a hot temp for the L98?
Matt
What is a hot temp for the L98?
Matt
RACE ON!!!
Le Mans Master
Joined: Jun 2006
Posts: 5,642
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From: One day you're a Comet...the next day you're dust... Arkansas
228* stop and go in the summer is not bad. Your main fan will come on at that temp if it were working correctly. Mid America has a 200* on 185* off sensor/switch kit. That is what I am using.
Thread Starter
Cruising
Joined: Aug 2006
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From: Marysville Washington
Wow, thanks everyone. I really do appreciate your assistance. I will do some research. I did not get an owners manual. When my father died I was left the vette, but couldn't find any manuals. I am ordering an owners manual and Chilton's. The car, unfortunately, will sit idle until I get back from Iraq.
Matt
Matt
Le Mans Master
Joined: Feb 2006
Posts: 8,753
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From: Louisiana
You really need a FSM, as suggested above, if you plan on doing any serious work on your vette. The Chiltons and Haynes manuals are O.K. to look at for pictures, but do not supply the information to specific things on your year car. The main fan should come on at 227* and aux fan at 235*. The main fan is controled by the ECM and the aux fan by a switch in the left head. If your temp was 225* on the highway then you have a cooling problem. Either debris between the radiator and condensor, air in the coolant, coolant leak, or faulty thermostat.
I would check the coolant level (flush if necessary), idle the car with the radiator cap off (watch temp) and fill as needed...this should release any air trapped in the system. Also at idle you will be able to see what temp the fan comes on at and check for leaks. Clean between the radiator/condensor. I wouldn't let the engine temp get past 240* at idle.
Do you remember what the oil temp was...related to the coolant temp?
I would check the coolant level (flush if necessary), idle the car with the radiator cap off (watch temp) and fill as needed...this should release any air trapped in the system. Also at idle you will be able to see what temp the fan comes on at and check for leaks. Clean between the radiator/condensor. I wouldn't let the engine temp get past 240* at idle.
Do you remember what the oil temp was...related to the coolant temp?
Thread Starter
Cruising
Joined: Aug 2006
Posts: 12
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From: Marysville Washington
Thanks for the tremendous amount of info. I will definitely get a factory service manual. I noticed the oil temp when I took out Labor Day was about 211 when the engine temp was 214.