Any ideas what's going on. The engine runs about 190 while driving around, but, in stop and go traffic the temps go all the way to 240. If I rev it up while at a stop the temps go down immediately. The radiator is in good shape as is the clutch fan and I have a 180 thermostat. The water pump does not leak. Any suggestions?

 

I dont know much about the clutch fans, but i think they go the same speed as the rpm's of the engine, so at idle its not spinning fast enough to cool down the engine, but if u bring up the rpm's the fan spins faster cooling it down some more.

what radiator cap and coolant mixture are u running?

 

Sounds like your water pump isn't moving enough coolant at idle. May be time for a new one. You should pop the radiator cap off at idle and watch to see if the coolant moves into the radiator turbulently. It should.

 

I'm running a new 16psi cap and I pressure tested the radiator. I just recently flushed the system and am running about an 80 percent water solution with anitfreeze and water wetter. Also, should it be fairly easy to squeeze down on the upper radiator hose with the engine hot and running? I think this overheating issue may be the cause of my car cutting out at the top of first gear when I stand on it and the engine is over 220.

 

It should be too hot to squeeze it. Like I said, make sure there is good coolant flow. It sounds like you may have an obstruction or a badly rusted/decayed water pump that isn't moving enough coolant.

You only need to pressure test if your coolant is boiling or if you think you have a leak.

 

Sounds like you need a high-flow water pump.