1996 cavalier 2.4 weird overheating issues
Asked by GuruDX1J2F Dec 03, 2024 at 07:58 PM about the 1996 Chevrolet Cavalier LS Convertible FWD
Question type: Maintenance & Repair
It only overheats at very low speeds low rpm’s or idling it boils a tiny bit but
does not build pressure, radiator is cold block tested it no head gasket leaks
bottom hose is cold upper inlet is hot. As long as i keep the rpm’s above 1500
it stays cool load makes no difference, it has tons of power runs like new but
temperature exceeds 215 while idling.
2 Answers
Sounds like the water pump. I had a similar issue with my 2000 Grand Prix several years ago. When I removed the water pump all the blades of the impeller were rusted away to the point that the pump was working, but at an extremely reduced capacity! The water pump was not leaking or noisy or anything. Also, be sure you don't have air trapped in the cooling system. Jim
GuruDX1J2F answered 2 weeks ago
It was a combination of a bad thermostat and the surge tank cap failing. Turns out if the surge tank doesn’t hold enough pressure it creates a pressure reversal in the radiator causing the reverse flow radiator to reverse its flow in the wrong direction through the surge tank. Think I saved the head gasket in time it’s now holding pressure and temperature is steady. Got a OEM 18 pound cap and put a fan switch that comes on at 195 degrees with a 180 degree failsafe thermostat. The reverse flow 2.2 scotch and 2.4 quad four between 95-2005 all have the same reverse flow surge tank systems on most models these engines were in. If it doesn’t hold pressure the coolant will not flow through the radiator instead it just sucks air in through the cap creating havoc. It’s never lost any coolant even when it would start to boil. But I have to drive it for 5k to really know if the head gasket is still ok. Ecu isn’t supposed to command the fan until 230 degrees really not smart engineering even though the thermostat OEM is 180.