My S-10 has been running hotter and hotter. I now this is a common problem with them, but it didn't used to get as hot as it does now. It is usually at a stoplight with the a/c on. Last year the waterpump started leaking real bad, so I replaced it with a new one. I want to flush the radiator (full flush). Is there anything I should use to help flush it?

How many miles? And how much do you drive it?

If it is older, with a lot of miles, and the core is messed up, I would replace or consider getting a new radiator.

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Its an '03 and just rolled to 86k. My commute to work is 10mi and takes 15 minutes. I have another car that I started to drive more to keep the miles off of the S-10. Yesterday it was 90deg here, and its temps were fine until I stopped for gas. When I restarted it the guage read 250, and within a few second dropped becuase it was able to circulate. But it wouldn't go below 210. It used to read around 195 and never sway, no matter what.

I never noticed any cooling problems with my or my BILs S10. I'm not sure if it's common on those. I'm wondering if you've got dexcool that's gunked up.

I have used those prestone adapters in the past and they seemed to work well with less mess. Some people just stuff a garden hose in the radiator. You might want to clean out the fins on the rad, and make sure you get a proper mix when you refill with radiator fluid.

Last year when I had to replace the pump I switched it from Dexcool. It still would get hot. I think I am going to pull the radiator to get it cleaned. I drained it this morning and used a hose to flush it out. With it drained I could tell there is a residue build up inside. I wiped part of it out with my finger, but will need a solvent to properly flush it. This was at the top, so I could only imagine the bottom of the radiator.

Maybe your fan clutch is bad? It's hydrostatic, the hotter it is, the more power to the fan blades... if it's running hot and you shut it off and the fan spins full speed for a longer then usual time, it might be shot.. you can also feel how much air flow you have passing through the fan..

Yes could be a radiator that is clogged internally or externaly ect.. just something I'd thought I'd throw out there, as the truck has a mechanical fan..

dexcool will really cause problems when mixed with the wrong green stuff.

leaking head gaskets.....check your oil, is there coolant in there? We had two different S-10's and both had head gasket problems. Did just what you are describing.

I have checked the fan clutch. You can hear it engage as the engine gets hotter. The anti freeze is the Prestone green "mix with any color". The oil is fine. It did have the intake gasket issue about two years ago, but it was leaking out instead of in.

The factory radiator is very small. Barely took a gallon to fill it back up. The oil change has maybe has 1k on it. I drove it after flushing the radiator, and it was fine until I shut off the engine. Then it wouldn't ever drop back to where it (I) would like for it to be again.

The ZR2 forum has a few post about this, but they all say to put on an electric with a bigger radiator. There has to be a better cure.

I took the radiator out yesterday and dropped it off this morning to be tested. When they called and said it was clogged it actually made me happy. I didn't have to continue with searching. It was $80 for a cleaning or $120 for a new one with a lifetime warranty. I paid the extra since I am not planning on getting rid of the truck.

Glad you found it. Sounds like dexcool sludge....ick. I'd power flush the block, too.