Had the baby out for a spin and noticed when driving up a hill the temp gage went up to around 220. Everything settled back around 200 when I went back down the car overheated, spilling out from the overflow tank. I'm the new owner of the car, a 79 auto, and the previous owner had new belts, hoses, radiator cap and supposedly drained and flushed the system. By the looks of the overflow container there appears to be some sludge. Any suggestions on where to start the problem finding process?

All C3's have over heating problems. Of course you should do the normal flushing stuff to make sure the fluid is good. Also check the thermostat and hoses etc. Another thing you should look at are the spacers around the radiator and the hood. I'm not sure what they are called, but they block the air from going past the radiator, making it directed onto it. Just missing one of these things can make a difference.

Maybe someone else could comment on what they are called, or other things to look for.
Glenn

It's fairly rare that a tech will clean out the overflow tank when flushing a system. They should, but most don't do it.

If all of that has been done (maybe not) I would look at the fan, the fan clutch, and the shrouding around the radiator and fan. These are common.

If the car is stock and has an EGR valve, make sure it's working. Oddly enough, an EGR valve not working will make the car run hotter. You may also want to check for advanced timing and lean fuel mixture.

I knew Ken would know more things to look for!

Thanks. I'm headed out to the driveway for some fun (?) with a wrench. Speak with you guys later.

Is it an L82? Make sure the electric auxiliary fan is hooked up and working. L82/AC equipted only. Mike

Not an L82 but does have a/c that is non-functional. The fluid appears to run through the radiator as the thermostat opens. I couldn't see anything obviously causing a problem so I took it out for a spin. What actually happens is that the temp stays stable around 180 then goes to 220 then back down to 180. It will bounce around every so often. Maybe the thermostat? I'll pull it later unless someone has any suggestions.

Thanks,Fran

I have run the full gambit with overheating in a '76. There were no profound problems found, but each thing I did helped. First, the original shroud was missing when I bought the car. This is a must have unless you want to go full blown high performance aftermarket radiator and fans. Second, the lower spoiler was missing. Another must have, especially if overheating at highway speeds. Third, radiator/hood weather strip seals. As mentioned, they direct the air through the radiator rather than around. Don't forget one at the top of the radiator, below the top of the frame. This one is not normally there but you will need one if the shroud is missing.

I went the 'upgrade' route and ended up with aluminum radiator, electric fans, high flow water pump, and all the stuff listed above except the original shroud. Worked out well for me but cost about $600. Remember that cooling in the C3s is marginal at best and any 'go fast' performance mods to the engine will complicate things somewhat.

Just my two cents....

Ken's right about the EGR. My '78 L82 was running a constant 210 degrees, even after a full power flush. I eventually removed the EGR and associated stuff and now the engine runs no more than 195-200 degrees.

Don't overlook the radiator cap. If it can't hold pressure anymore the car will overheat. That should be a standard thing to check when also doing a pressure test on the whole cooling system, but often gets overlooked.

Owen, are you happy with the performance now?? And when replacing with ele fans, do you still need the shroud? Im rebuilding my 71 with a little more HP and the old radiator is toast. I was considering the same but was unsure if it was worth the extra $$..

Thanks