What could cause a C5 n/a ls1 eng. to overheat when both fans are running? Checked fluid level which was fine and both fans are running. It began to run hot today for the first time this summer. (240 degs.) With the a/c off it seems to be ok, only run hot with the a/c on. There was no trash on the radiator. Outside temp. was about 94 degs.

 

Did it actually overheat, or just get hotter than you expected. 240 is not the end of the world!

Anyway, check the front of your radiator for debris. If you have had any reason to drain the coolant, there could be a bubble in the system, but that doesn't sound like a possibility for you.

If you were at 240 in traffic, idle, etc, I wouldn't worry about it. If you are at 240 cruising down the highway, you may have something going on.

Dave

 

How do you get bubbles out of the system. My coolant was recently changed and I don't thik the mechanic did it correctly. Im running hotter now.

 

If your pump is good , thermostat, dexcool, and the fans are working...its possible to hit 240 F... although I was amazed at how much junk and debris and feathers and twigs and pollen etc, I removed from between the radiator and condensor... if you look up between the two from the bottom you will see what i mean.. I removed a clump of crap fromthis area that you would not beloieve I am sorry I didnt take a picture,... but it looked like what would come out of a vacuum cleaner bag.... a clump of stuff about 6 X 6 inches by 4 inches.. I made two tools to clean this area...one was a detail brush on a 18 inch dowel for brushing the stuff lose. then I made an air adaptor from a piece of 1/2 in copper tubing I flattened it, drilled a few holes in it and added a fitting for my compressor... to blow the lossened stuff out.... it made a big difference...btw the fans cycle from high speed to low speed... and come on earlier if the ac is turned on...the high speed fans comes on around 220 . with the ac on, the high speed fans will cycle periodically to reduce the head pressure/...( compressor ) the car should run cooler with the ac on .. that is unless the condenser is clogged...


[Modified by Evil-Twin, 6:57 PM 7/12/2003]

 

I`ll take a look between the rad. and the condenser and hope that`s all it is. I thought it may have been the fan not working because the eng. temp. dropped pretty fast when I turn the a/c off, but temp. went up fast as well when I turned the a/c on. :confused: