Specific overheating problem, please help!
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Instructor
Joined: Apr 2015
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From: San Antonio TX
Specific overheating problem, please help!
Hey everyone, I'm having a specific overheating problem that hopefully someone can help me figure out. When the car is moving the coolant temp is perfect around 190. If I start the car and let it idle for a while the temp will go up to about 206 then drop down to 196 after the second fan turns on. If I am driving around and stop at a fast food drive through for example the temp will go all the way up to high 240s then SLOWLY drop to normal temp or it will just stay at high 230s till I start moving again. What is the most likely cause for the car to be overheating at a stop but nice and cool while moving?
2003 C5 Z06 stock 160k miles. Water pump replaced at 80k miles. I use the correct 50/50 premixed coolant last year. No dirt or debris in the radiator.
2003 C5 Z06 stock 160k miles. Water pump replaced at 80k miles. I use the correct 50/50 premixed coolant last year. No dirt or debris in the radiator.
Last edited by JDMricist_03; Aug 21, 2020 at 11:50 PM.
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Impossible to say for sure without knowing anything about your car specifically, but I’d guess a good cleaning of your radiator and condenser would be a good place to start.
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From: San Antonio TX
Added a bit more info on the last sentence. We can agree that these temps aren't normal right? People keep trying to tell me it's normal but it never used to get over 134* even in the middle of summer parked and running for 15+ minutes. Also if it was the water pump it would get hot even when moving right?
Last edited by JDMricist_03; Aug 21, 2020 at 11:58 PM.
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Added a bit more info on the last sentence. We can agree that these temps aren't normal right? People keep trying to tell me it's normal but it never used to get over 134* even in the middle of summer parked and running for 15+ minutes. Also if it was the water pump it would get hot even when moving right?
Has the radiator and condenser ever been cleaned out? If it has 160K miles and hasn't, I bet there is more stuff in there than you think. I clean mine out at least once every year and there is always small pieces of grass and bugs and everything else on the road that gets sucked up in there, being a bottom feeder. (I am supercharged and that makes it way worse, my car is like a street sweeper)
Again, impossible to say with absolute certainty, but if it has never done this before, something has changed that is causing it to not run normal.
Have you also checked to make sure both fans are working?
Your OEM fan settings are set to come on @ low speed fan should come on at 226* and high speed fan at 235*, unless these parameters have been changed by a tuner.
Based on what your saying, my best guess again is an airflow issue, and these are the things that affect airflow.
Hope that helps.
Pro
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Difficult to tell the difference between "idling for a while' at 206 and stopping after driving in the 240's.
Generally, problems while stopped are the fans, although a dirty radiator can also contribute. The second fan does not come on, both run together on either high or low speed. IIRC, low on a 225 off at 219, high on at 235, off at 226.
I have lost two fan motors. The second one was intermittent until it finally quit, which could be your problem
When it gives the problem while stopped, check that both fans are operating and at what speed by listening and carefully putting your hand behind the fans.
Generally, problems while stopped are the fans, although a dirty radiator can also contribute. The second fan does not come on, both run together on either high or low speed. IIRC, low on a 225 off at 219, high on at 235, off at 226.
I have lost two fan motors. The second one was intermittent until it finally quit, which could be your problem
When it gives the problem while stopped, check that both fans are operating and at what speed by listening and carefully putting your hand behind the fans.
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Hey everyone, I'm having a specific overheating problem that hopefully someone can help me figure out. When the car is moving the coolant temp is perfect around 190. If I start the car and let it idle for a while the temp will go up to about 206 then drop down to 196 after the second fan turns on. If I am driving around and stop at a fast food drive through for example the temp will go all the way up to high 240s then SLOWLY drop to normal temp or it will just stay at high 230s till I start moving again. What is the most likely cause for the car to be overheating at a stop but nice and cool while moving?
2003 C5 Z06 stock 160k miles. Water pump replaced at 80k miles. I use the correct 50/50 premixed coolant last year. No dirt or debris in the radiator.
2003 C5 Z06 stock 160k miles. Water pump replaced at 80k miles. I use the correct 50/50 premixed coolant last year. No dirt or debris in the radiator.
In other words sounds like the car is fine.
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From: Chandler AZ
I think 228 is the highest my Corvette has gotten to in a long drive thru without A/C on, and it seems it's cooler with A/C on because fans run non stop.
Are you sure your coolant pressure tank is ok?
Mine had a hidden crack where the hose slips on, and would leak a tiny bit of coolant but only after a long drive.
Apparently it's a common issue on these cars and might be caused by leaning over fender to work on car.
Or a leaking radiator hose, or like others said dirty radiator.
It can be hard to tell if both fans are running, especially the driver's side but you can check next time you have car on ramps or jack stands, get under car to see.
How old is the coolant? Edit I forgot it was new coolant.
Are you sure your coolant pressure tank is ok?
Mine had a hidden crack where the hose slips on, and would leak a tiny bit of coolant but only after a long drive.
Apparently it's a common issue on these cars and might be caused by leaning over fender to work on car.
Or a leaking radiator hose, or like others said dirty radiator.
It can be hard to tell if both fans are running, especially the driver's side but you can check next time you have car on ramps or jack stands, get under car to see.
How old is the coolant? Edit I forgot it was new coolant.
Last edited by 1999corvettels1; Aug 22, 2020 at 07:01 AM.
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These cars are designed to run warm. Yours sounds normal. Mine got warm, 230ish stopped in traffic and leaving the A/C (on which keeps the fans running) cured that concern. (as previously said)
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As U know these cars run hot and what you describe is not excessive heat. My Z heats up quickly sitting in stop and go traffic and drive through until fans come on. If your fans are working properly get you a coolit mod device from sac city that allows you to turn on you high speed fan anytime with a fob. Around 140.00 and installs in 10 minutes. Several post on here about coolit mod. Good luck with it.
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Considering the fans don't kick on to 235 I really don't see 240 as being too extreme. Personally, I don't like temps that high. If I was in your shoes, I'd clean the radiator (again) and also the condenser. If that doesn't fix the problem, I would either have the fans reprogrammed to come on earlier or get a Coolit.
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Everybody has the right idea. Rad clean, fans programmed. and 160 thermostat.
Good luck
Good luck
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From: San Antonio TX
Hey guys, everyone that responded, thank you so much for yall's input. Pretty much every post helped in some sort of way so again, thanks. Coolant pressure is good, no blockages, probably not the water pump, but it looks like the drivers side fan isn't spinning but the passenger's side fan turns on at about 225ish. The driver side fan is supposed to be spinning before the passenger side fan does right?
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Right, the drivers side is the low speed fan and should be the first one to come on. With your mileage, maybe time for new fans. They aren’t too expensive to replace.
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Both fans come on at low speed or high speed. As for as temps this is a quote from Evil Twin
FYI:
Depending on the model year...
For later model years:01-04
The low speed cooling fans are commanded on when the coolant temperature reaches 108°C (226°F). They are turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fans are commanded on when the coolant temperature reaches 113°C (235°F). They are turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fans will be turned on at vehicle speeds less than 56 kPh (35 mph).
For early model years:97-00
Low speed fans come on at 219,high speed fans come on at 228,low speed with a/c on...
FYI:
Depending on the model year...
For later model years:01-04
The low speed cooling fans are commanded on when the coolant temperature reaches 108°C (226°F). They are turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fans are commanded on when the coolant temperature reaches 113°C (235°F). They are turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fans will be turned on at vehicle speeds less than 56 kPh (35 mph).
For early model years:97-00
Low speed fans come on at 219,high speed fans come on at 228,low speed with a/c on...
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I stand corrected, yes both fans should be running either at low speed or high speed at the above mentioned temps.Still sounds like your drivers side fan has run its course.
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