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C5 Overheating BAD!! Help!

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Old Jun 16, 2022 | 10:53 PM
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Sounds like you were around town type driving.

First thing I would check would be the fan operation, both on low at 226 F, both on high at 235. Both on aqt 185 with A/C.

I have had several fan motor failures.
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Old Jun 17, 2022 | 01:20 AM
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I have done a 80/20 mix water to anti freeze my temps never get over 210 degrees, Mycar is cammed procharged making over 800 hp. I live in fla so it does not freeze here.
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Old Jun 17, 2022 | 02:03 AM
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Originally Posted by gimp
Pull off to a parking lot, pop the hood, check to see if they are spinning. Or listen for the sound of them turning on. Some people even wire a light into the circuit, though I wouldn't recommend doing that unless you know exactly how.
Thanks, that was what I was thinking, but I saw a YouTube vid where the dude said he could not see the fans. I guess I gave up too soon after hearing that. I will be checking that tomorrow. But not the wire a light into the circuit idea, I am not that competent nor confident.
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Old Jun 17, 2022 | 02:09 AM
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Originally Posted by wrmiles
Sounds like you were around town type driving.

First thing I would check would be the fan operation, both on low at 226 F, both on high at 235. Both on aqt 185 with A/C.

I have had several fan motor failures.
My C5 only gets to 218-220 F. with the AC off. Perhaps I'll try to activate the AC and check the fans; if the needle starts heading to the right, I will shut the engine down. Thank you.
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Old Jun 17, 2022 | 02:12 AM
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Originally Posted by corvet786c
I have done a 80/20 mix water to anti freeze my temps never get over 210 degrees, Mycar is cammed procharged making over 800 hp. I live in fla so it does not freeze here.
Nice numbers. My 2010 SS Camaro dynoed 769 rwhp, charged and cammed with every single bolt on and tuning. But it's a moot point now. The SS is a pile of ashes as of 4 months ago.
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Old Jun 17, 2022 | 10:48 AM
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Originally Posted by zztopo
Nice numbers. My 2010 SS Camaro dynoed 769 rwhp, charged and cammed with every single bolt on and tuning. But it's a moot point now. The SS is a pile of ashes as of 4 months ago.
If u have someone by the fans , when u turn on a/c u will definitely hear the fan kick on. Dont b dumb like GRINDER. He had someone turn on the a/c and he checked with his fingers. Maybe thats why he always giving me the bird when he wavies at me when he gets home. I just thought he didn't like me..Last finger standing. dumb butt. God if i told u all the things hes done working on peoples cars, i would have to have finger replacements.
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Old Jun 17, 2022 | 11:15 AM
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Lower temp Tstat won't help since the stock is opened fully at 186°.
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Old Jun 17, 2022 | 11:36 AM
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Originally Posted by zztopo
Thank you very much. I was hoping for a "false alarm," but it is real. I just took it for a quick spin without the AC on, and it stayed at 218F* F. What a shitty time for the engine and AC to hate each other; we're breaking heat records with no end in sight! I guess I'll be sweating my *** off until I do what you suggested. I don't have $ for a new water pump. Question: I want to change to 160* stat. I don't like my engines running that warm in this goddamn heat. Good idea?

Again, thank you for responding.
I hope this isn't the problem, but I'll share it anyway; I had an '85 IROC Z. Had a mild 350 SBC transplanted by someone before I bought it. Whenever the A/C was used, the engine would overheat, even at 65-70mph freeway speeds. I later discovered that as soon as the compressor put that extra 3-5hp drag on the engine, air bubbles in the recovery tank!! Found out one blind hole in the front of the block had a bolt that was maybe 1/4 too long. When torqued down, it didn't clamp nearly down enough to seal head gasket to block and head!!! Ground the bolt shorter, no more overheating. Most all the late model blocks, SBC, etc. all have blind holes. The early small block with open threaded holes wouldn't have had this issue. That extra drag was enough to cause the headgasket to leak combustion chamber heat into the coolant, boiling it..........
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Old Jun 18, 2022 | 06:57 PM
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Ok guys poked inside the engine bay to check out the fans. The passenger-side fan is the low speed fan, right? It kicked on at around 215*. With that said, I tried to see the other fan (driver's side) but I can' t see it. Am I missing something?

Also I discovered this behind the airbox. Did the shop disconnect this when they installed my new MSD 2 step?

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Old Jun 18, 2022 | 07:09 PM
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Should be two fans they both turn on together on low speed at the lower temp set point, and then both go to high speed when the higher temp set point is reached.
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Old Jun 18, 2022 | 08:08 PM
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Originally Posted by jim993
Has there been any work on the cooling system recently? What is the coolant level?
Coolant level is up. But the C5 was bought from a private owner and there were no maintenance records.
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Old Jun 18, 2022 | 08:09 PM
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Originally Posted by mmartinez
Should be two fans they both turn on together on low speed at the lower temp set point, and then both go to high speed when the higher temp set point is reached.
Do the 2 fans sit side-by-side. I got shitty 61 year old eyes, I'll double check tomorrow to see if I can eyeball both fans.
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Old Jun 18, 2022 | 08:16 PM
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If the fans are running you can feel air coming out the back of the shrowd at each fan.
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Old Jun 18, 2022 | 08:19 PM
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Originally Posted by wrmiles
Sounds like you were around town type driving.

First thing I would check would be the fan operation, both on low at 226 F, both on high at 235. Both on aqt 185 with A/C.

I have had several fan motor failures.
Ok thanks!

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Old Jun 18, 2022 | 08:20 PM
  #35  
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Originally Posted by jim993
If the fans are running you can feel air coming out the back of the shrowd at each fan.
I can't wait to check tomorrow, thanks!
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Old Jun 18, 2022 | 10:16 PM
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Originally Posted by Cohiba
Lower temp Tstat won't help since the stock is opened fully at 186°.
Yup, I've ditched that idea after all the research I've done, thanks.
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Old Jun 18, 2022 | 10:21 PM
  #37  
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I'm thinking condenser overheat and/or leak in the AC system. I'm thinking the fans are ok. If the fans are the problem, then (I think) my water temps would be high when running without the AC. The C5 ran at a steady 215* today, and it is still hot out.

Hopefully, the C5 just needs a blow job.

Just like me.
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To C5 Overheating BAD!! Help!

Old Jun 19, 2022 | 02:27 AM
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Is that 215° with ac on?

I was driving around today in the 90’s with the ac on and the water temp was holding about 200°. You may indeed have some blockage.

Check out this post…

https://www.corvetteforum.com/forums...post1605291551
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Old Jun 19, 2022 | 11:05 AM
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Originally Posted by vette4fl
Is that 215° with ac on?

I was driving around today in the 90’s with the ac on and the water temp was holding about 200°. You may indeed have some blockage.

Check out this post…

https://www.corvetteforum.com/forums...post1605291551
215* with AC off.

Hey thanks!
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Old Jun 19, 2022 | 01:01 PM
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Just a quick reminder that in a stock C5 your stage 1 fan isn't even set to come on until your engine reaches 226°. Also it has conditions for the A/C.
If the A/C is on, the 1st fan should come on at 185° which means it should basically be on all the time if everything is working correctly as you have a 187° thermostat.
My first step would be making sure the car has enough coolant, then check the cap, then hoses and fans before I thought about the water pump unless your car is leaving puddles after being parked.
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