2003 C5 running hot at idle
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2003 C5 running hot at idle
Hello, I'm looking for information on what could be causing my car to run a bit hot at idle or slow speeds. Its hoovers around 240 temp but only does it at idle. When I'm driving at speed it's around 218, slightly under the middle mark on the temp gauge. As far as I can tell both fans are running and the coolant is a greenish yellow color. Im not seeing the the index marks that the manual says to use to check the coolant level, so I'm not sure if it's low or not. Any suggestions or info would be appreciated. Thanks
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well if you have done nothing to the car recently I would check the radiator for debris you will most likely have to get under there to really look....a plastic bag perhaps....dirt and grass ain't enough by itself.
any signs of leaking from the water pump? maybe the impeller is crap and not moving water as effectively as it should....
only time both fans run is if the AC is on or you reach 226 (I think)
I'm sure 8vette7 will be along shortly with his excellent primer on this issue
any signs of leaking from the water pump? maybe the impeller is crap and not moving water as effectively as it should....
only time both fans run is if the AC is on or you reach 226 (I think)
I'm sure 8vette7 will be along shortly with his excellent primer on this issue
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In regard to the fans, I let the car warm up in the driveway withe the a/c off. When I first cranked it there was only one fan on but when the temp reached around 220 the second fan would turn on, run for a bit, then turn off. It would repeat this process while the car was running at temp. I would assume that the fan is operating correctly doing this?
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when you say blow the radiator out, do you mean using a air compressor with a air nozzle?
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Hello, I'm looking for information on what could be causing my car to run a bit hot at idle or slow speeds. Its hoovers around 240 temp but only does it at idle. When I'm driving at speed it's around 218, slightly under the middle mark on the temp gauge. As far as I can tell both fans are running and the coolant is a greenish yellow color. Im not seeing the the index marks that the manual says to use to check the coolant level, so I'm not sure if it's low or not. Any suggestions or info would be appreciated. Thanks
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In regard to the fans, I let the car warm up in the driveway withe the a/c off. When I first cranked it there was only one fan on but when the temp reached around 220 the second fan would turn on, run for a bit, then turn off. It would repeat this process while the car was running at temp. I would assume that the fan is operating correctly doing this?
Last edited by 65GGvert; Sep 8, 2015 at 12:49 PM.
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Both fans should run on low speed, and both speeds should run on high speed. They don't ever run only one at a time. The temp these fans run low and high is set by the tune. If you're stock, both fans should run on high when temp reaches about 236 degrees and switch back to low when it reaches around 219. You may have one of the 30 amp fuses in the under hood fuse box blown. The fact that it cools down at speed tells you that the radiator is reasonably clear. The fans turn off at 35 mph and don't help cool. I'd look seriously at the fuses and/or relays that run the fans.
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I'll have to check it again... got it from a chevy dealership so I would assume that they checked the coolant to make sure it was right.
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I just replaced my water pump, hoses and radiator at 130,000 miles. The coolant temp is 200 or less while driving (outside temp at 100 dF). While idling it might reach 205.
Before I did this, it was between 225 and 235. I tried cleaning the old radiator and that helped a little.
I bought a exact gm radiator for $205. Totally fixed it.
Also be sure when you refill the coolant, that you burp the engine. This is a procedure to get the air out of the cooling system. It works.
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From: Dallas Tx
Get under the car and check for leaks. Use a good flash light and have a good look around.
On a 12 year old car, I would look carefully around the radiator hoses and water pump area. The overflow reservoir has a real thin plastic pipe (that connects to a small radiator hose) - that likes to crack. If there is any leak at all, the coolant will not get pressurized. I had to replace that reservoir also.
I tried to replace the hose clamps with some stainless steel type (with a screw). Those did not work at all. Ended up going back to the gm clamps I had.
Most of these parts are pretty cheap (in vette terms). Just get the exact gm replacement. The original stuff lasted 10 years - good enough for me...
On a 12 year old car, I would look carefully around the radiator hoses and water pump area. The overflow reservoir has a real thin plastic pipe (that connects to a small radiator hose) - that likes to crack. If there is any leak at all, the coolant will not get pressurized. I had to replace that reservoir also.
I tried to replace the hose clamps with some stainless steel type (with a screw). Those did not work at all. Ended up going back to the gm clamps I had.
Most of these parts are pretty cheap (in vette terms). Just get the exact gm replacement. The original stuff lasted 10 years - good enough for me...
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HOW did you get under the car and clean the Radiator?
The A/C Condenser sits in front of the radiator...unless you took the A/C Condenser OUT there is only about 3/4 of an inch between the A/C Condenser and the Radiator... I don't know how you would wash it.
The BEST method to REALLY clean your Radiator is to TAKE IT OUT...
The A/C Condenser sits in front of the radiator...unless you took the A/C Condenser OUT there is only about 3/4 of an inch between the A/C Condenser and the Radiator... I don't know how you would wash it.
The BEST method to REALLY clean your Radiator is to TAKE IT OUT...
Last edited by 73Corvette; Sep 8, 2015 at 05:31 PM.
Instructor
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From: Dallas Tx
HOW did you get under the car and clean the Radiator?
The A/C Condenser sits in front of the radiator...unless you took the A/C Condenser OUT there is only about 3/4 of an inch between the A/C Condenser and the Radiator... I don't know how you would wash it.
The BEST method to REALLY clean your Radiator is to TAKE IT OUT...
The A/C Condenser sits in front of the radiator...unless you took the A/C Condenser OUT there is only about 3/4 of an inch between the A/C Condenser and the Radiator... I don't know how you would wash it.
The BEST method to REALLY clean your Radiator is to TAKE IT OUT...
Easy to get under and blow out the dirt with a air compressor and wand. I take the top radiator holder off (4 bolts) and separate the a/c condenser and disconnect the fan. It is a pain but doable...
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From: OK
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Do a search here on overheating you will find good information on how to clean your radiator, the correct fluid, and other good suggestions on how to keep your cool.
It is also a good forum practice to post specifics about your car, i.e. is it modified with any power upgrades, exhaust, etc. This information helps folks respond to your question. My '04 is highly modified so I've done several upgrades to help keep it cool. If your's is not follow the advice that has been recommended. Clean out the radiator; change the fluid to the correct antifreeze; verify your thermostat is opening correctly; do a visual inspection for leaks; and make sure that you have cleared the air out of the system (burped it).
I've just changed out my radiator due to leaks, the OAT's have been around 90 to 100 and my temps run around 195 to 205. That being said I have a highly modified cooling system so I tend to run on the cooler side on the street so that I can hold temp on the track.
Welcome to the forum and always check here before you go to the dealer.
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I mentioned the 30 amp fuse because I had the same issue on a used 2004 I bought last year. Before I left the lot, their mechanic checked it out and one of the large green 30a fuses was blown. He changed it and I had no more trouble with the fans. My recollection is that there are 3 of them, but they're easy to measure.