replaced waterpump , thermostat 185 degree, new water temp sensor, new hoses upper and lower, new coolant fan relay
my car still overheats at idle to 240 degrees in which i shut it down. when i replace the thermo i notice yellow-brownish rust, did the flush my self and installed everything above. Put fresh coolant in could there be air in the system?.could there still be debris in the coolant system and have to reflush? the heater is kicking out heat and both radiator hoses feel warm and full. there is no white smoke and no water on the dip stick ,the motor runs smooth. the fan kicks on at estimated 230 degrees put temp still rises to 240. any suggestions would be a great help.

 

Corvette are just hot running cars in my opinion. I would say you could replace the radiator to a better flowing one and that might help.

 

Your gauge may not be accurate. Use one of the hand held digital thermometers and confirm the 240 reading. If you do not have one they cost about $100.00 or you can rent one.

 

You put in the 185deg. stat but you still need to change your temp sensor for the fans to kick on earlier. On my 88 I have factory aux. fans (located on the front of the radiator)and they are controled by a switch thats on the drivers side of the block in the #5 cyl. area. Replace this switch with a lower temp switch. The switch I put in turns this fan on at 180 deg. The main fan on the engine side of the radiator is controlled by the ECM. If you have these aux. fans your good to go. Just add the switch.Like $30. otherwise you'll need to add aux fans.

Without getting your fans to come on sooner your temp will climb up to 240. the fan first starts at 230 and it just can't get rid of the heat fast enough without you moving at highway speeds.( I am assuming your checking these temps at an idle.)

 

Try running the hose over the radiator with the car running, this may keep the radiator cooler allowing the heat exchange to help the car run cooler. My father had this problem with his 94. Take the radiator out of the car and run the hose backwards through the fins pushing out dirt and leafs and rocks and all kinds of foreign objects into the cooling fins. Also, blow air through the cooling fins backwards. put it back in the car and away you go. Seems to work best by taking the radiator out of the car so you can see it and also clean the shroud.

Good Luck

 

This is gona sound very stipid but check between the radiator and the A/C condenser. You will be surprised to see what gets suck up there on a C4 and if the radiator doesn't get airflow it won't cool.

 

One thing you might want to try is "burping" the system. With the rad being lower than the engine, you can get air pockets in the engine. With the radiator cap off, start the car and leave it warm up until the thermostat opens up. Place a rag over the filler tank to keep antifreeze from splashing all over and then grab the upper radiator hose with both hands and give it a few good squeezes. Replace the radiator cap and squeeze the hose again. Shut the car off and let it cool and repeat the process.

All the information in this thread is very good but I tend to start with the simple stuff and work my way up.

 

One more thing to do is do a cooling system leak down test. If you have a bad head gasket it could poassbly be pushing heated combustion gases into your cooling system. I've never witnessed it but have heard of it happening. But there are many really good sugestions posted here. This would be a last resort item.