Coolant System Trouble?

So I have been having this problem consistently for the last 2 years. My car tends to overheat in the summer, quickly when it is really hot, or slowly when i am travelling longer distances and the weather is mild. I have replaced the fan clutch, the thermostat, and have had it looked at by several mechanics, there appears to be no pressure problems or leaks and the everything else seems to be working fine other than the fact that it overheats (only in the summer). Any suggestions?

Not a mechanic or anything but, have you tried using that 'super coolant' stuff that they have at auto parts stores? thats what I would try...

Sounds to me that your cooling system doesn't have the capacity. You might need to have the radiator rodded out. Can you give some specifics, such as engine size, car year etc?

maybe try a hi-flow waterpump

If your was an 80s model, your radiator is plugged up (hence reduced cooling capacity). It's also a 2-row core, and I went to a 3-row. Worked great for many years.

I also installed an external trans cooler (in series) to take some of the stress off the cooling system.

When I swap engines out (I keep saying I'm gonna do that, but the engine simply won't die on its own), I plan on going with an engine oil cooler as well.

I'd go with the bad radiator diagnosis. I have never had a Caprice overheat on me, it's not in the car's nature to do so. The radiator might be full of stop leak or some other cooling additive. When you get a new one (check out NAPA they got good price$) compare the weight of the old one, if the old one is a lot heavier, it was definitely clogged up.

Bob

gotta 96 caprice 9c1 had the same problem in mine in the summer time pissed me off cuz i couldn't take long trips. anywayz the caprices have a lil weak spot which is the coolant box, it breaks easily. mine had a hair line crack but it sipping out alot of pressure. got it changed an it worked fine.check the radiator also. if urz was a 9c1 the rad fail that easily.

good luck!

gotta 96 caprice 9c1 had the same problem in mine in the summer time pissed me off cuz i couldn't take long trips. anywayz the caprices have a lil weak spot which is the coolant box, it breaks easily. mine had a hair line crack but it sipping out alot of pressure. got it changed an it worked fine.check the radiator also. if urz was a 9c1 the rad **shouldn't** fail that easily.

good luck!