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C4 Cooling and Heating Systems

my 1990 runs above 230 degrees (1/35)
 8/21/12 12:35am
BillyDee
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Vette(s):
1990 convertible corvette,owned 1 year


Joined: 8/9/2012
Posts: 51

   My 1990 runs above 230 at a stop light has went as high as 250 and this concerns me but back on the hihgway its runs at 160 thats a big difference.Im thinking of installing a extra fan but its very tight in the engine compartment,has anyone installed a cooloing fan and if so did it help and where did you put it? Thanks for any info

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Re: my 1990 runs above 230 degrees (2/35)
 8/21/12 8:10am
SAYWHEN
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Posts: 82

'90 should already have two cooling fans ??...one behind the radiator and a aux. fan in front of the radiator/ condenser. 230* (which IMO is hot) is NORMAL for these cars to run in the summer heat, sitting idling. However 250* is NOT normal and not good....be certain both fans are running. If the fans are both there and running..check for debri (leaves,paper/plastic bags etc.) in front of the condenser and between the condenser and the radiator. Any sort of blockage of the fins on the condenser or radiator can cause overheating. The opening at the front of these cars doesn't let much air in...but it does work well as a vacuum cleaner for sucking up road debri..LOL
 
The thermostat controls the low side of engine temp---the fans SHOULD be controling the high side of engine temps when idling. The 165* highway temps sound low..... should be around 195* (stock thermostat) It's possible the thermostat may be partially stuck open.
 
The above ideas are based on a STOCK C4---if any mods or repairs (water pump,hoses,system flushing, lower temp. thermostat etc.) have been performed recently it's also possible you have air in the system. JMO


|UPDATED|8/21/2012 5:10:41 AM (AZT)|/UPDATED|
Re: my 1990 runs above 230 degrees (3/35)
 8/21/12 1:11pm
Adams' Apple
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Duncanville, TX - USA

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1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
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WOW!!! I agree...250* is TOO hot! 230 is fairly normal in town/traffic/stopped, but seeing 250 would scare the bejezzus outta me.
If it cools back down once you get moving, I'd also agree that you may have a cooling fan problem. You should be able to hear the fan(s) come on if you're siting in traffic, or at a light. The main fan should come on around 228 or so, but should definitely be on by 240.
The fan relays have been a problem on some year cars. If you fan does not run at all, even with the A/C on, I'd start with fuses, then relays, then check to see if the fans will run if hot-wired.


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Re: my 1990 runs above 230 degrees (4/35)
 8/30/12 12:52pm
epohdivad
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Kearns, UT - USA

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1990, L98, 6 Speed Manual, Brilliant red metallic


Joined: 4/6/2012
Posts: 86

My '90 was doing the same thing.  Per comments on this forum I pulled the radiator cover and found fur, bags, grease etc all over the radiator.  I got that all cleaned up (driveway was nasty!).  It was running much better at speed, but still when stopped the gauge climbed and I even had the "check gauges" light come on the dash.  I wasn't able to ever hear the main fan come on, and am not able to with my schedule to see if the relay/fuses/fan were okay.  I took it to my local dealership and they found the main fan shorted out along with the fusible link.  I had them check the radiator fluid and it wasn't very good so they did a drain and fill.  They also noted the thermostat wasn't working to well so they swapped that too.  Bit expensive of a job, but much better than a major breakdown due to overheating!



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Re: my 1990 runs above 230 degrees (5/35)
 10/6/12 10:32pm
BillyDee
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1990 convertible corvette,owned 1 year


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Posts: 51

Thanks to all for the info and i have checked alot thats been suggested except the hot wiring  of a particular fan could you tell me exactly how thats done?I have noticed that the driver side fan comes on when the a/c is on but neither of the fans come on at all even at 235 degres fortunately the car doesnt overheat but i feel that the fans are the issue and or the radiator to some degree.Ive heard of fuses and relays im not sure where their located so i can check them again any info on this issue is apprecited and thanks again

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Re: my 1990 runs above 230 degrees (6/35)
 10/6/12 10:34pm
BillyDee
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1990 convertible corvette,owned 1 year


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Posts: 51

Thanks to all for the info and i have checked alot thats been suggested except the hot wiring  of a particular fan could you tell me exactly how thats done?I have noticed that the driver side fan comes on when the a/c is on but neither of the fans come on at all even at 235 degres fortunately the car doesnt overheat but i feel that the fans are the issue and or the radiator to some degree.Ive heard of fuses and relays im not sure where their located so i can check them again any info on this issue is apprecited and thanks again

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Re: my 1990 runs above 230 degrees (7/35)
 10/8/12 10:49pm
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2135

BillyDee said: fortunately the car doesn't overheat but i feel that the fans are the issue and or the radiator to some degree.

If it is actually getting to 250 deg, it IS overheating! I would suggest that you maybe get/borrow an infrared temp gun and actually check the temps...the gauge may be wrong, and that would explain why the fans are not coming on when you think they should be on. If the fan is coming on with the A/C, then that fan, and relay are good, as are the fuses for that fan.
The ECT(engine coolant temp) sensor, which sends coolant temp info the the ECM, is different from the temp sensor, which ONLY supplies info for the gauge. Your ECT may be fine, but the temp sensor for the gauge may be flaky....


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Re: my 1990 runs above 230 degrees (8/35)
 10/10/12 7:24pm
helphos
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Olney, MD - USA

Vette(s):
93 Polo Green Convertible with Bilstein Shocks, Autopower RollBar, Simpson 5 point harness, Grand Sport wheels, bald tires and dirty air filter!


Joined: 10/20/2010
Posts: 44

Previous owner installed a fan ovverride switch that allows me to force one or both fans on at any time.  That was useful when my Vette was overheating.
But I decided to find the underlying problem, and sure enough, it turned out to be debris between the radiator and the AC condenser.  I vacuumed it out with a shop vac and that solved the overheating problem (mine was going over 240, which was scaring me!).

New antifreeze with "Water Wetter" (commercial product to make the water flow faster) also gave me peace of mind.

Good luck!
Paul


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Re: my 1990 runs above 230 degrees (9/35)
 10/22/12 6:09am
BillyDee
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Vette(s):
1990 convertible corvette,owned 1 year


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Posts: 51

     Thanks to all for the info and im still having temp issues and from what iv read im going to remove the radiator and clean it maybe replace it and while im in there check out the cooling fans now the primary fan on the drivers side comes on only when the a/c is turned on but i dont think either fan works like they are supposed to  on their own, how do i check them? i have read that you can wire them so that both fans come on when the primary comes on but it doesnt come on as you can see this is my first vette actually a surprise birthday present from my awesome wife a 1990 convertible and it has issues but im gonna try like hell to her road worthy now that i know vettes run higher on temps im not so worried but i do need to get the cooling fans fixed plus is there a video on intake removal cause mine has a intake leak on the passenger side that must be fixed...again any and all info is greatly appreciated and im so glad i found this site cause you all help others so much and to me thats pretty cool

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Re: my 1990 runs above 230 degrees (10/35)
 10/22/12 10:14am
Adams' Apple
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Duncanville, TX - USA

Vette(s):
1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.


Joined: 3/18/2009
Posts: 2135

Bill, I sent you some troubleshooting info, and the cooling fan wiring diagrams....hope those help. Thumbs Up

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Joel Adams  
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"