Hey all, I'm new here so thanks for letting me join. My 2006 G35 sedan overheats. It is in Port good shape with about 110k miles on it. The overheating started because the car would never warm all the way up. So I went to replace the thermostat and found that it didn't have one in it. Probably to hide the overheating issue. It was regular but kind of intermittent at first and then got worse. Heater doesn't blow warm air. It loses water but not into the oil, I think it boils out, the overflow tank will literally be at a rolling boil. I had it pressure tested and the head gaskets passed. Water pump had been replaced and radiator cap. Mostly everything really in the cooling system accept the radiator and the heater core. It would do this strange thing where it would get hot all of a side then cool off and be fine. It also quit overheating completely off about a two month period straight with no issues. But now it's back and everyone I drive it it overheats. Is this the heater core? The part is cheap enough I just don't want to tear the whole dash out and replace to find out it's the motor or radiator.

Please advice and thank you again!

 

If your heater core has a hole in it you would have water on the floor and smell antifreeze really bad. If it was clogged it wouldn't make the engine over heat but would keep you from getting cabin heat. It sounds like you have a leak in your cooling system. If it's not sealed and under pressure it will boil because it has air in the system. I would get a radiator pressure tester and put it in a really quiet garage and start checking for leaks (hissing). A bad tank seal on the radiator, bad hose, loose clamp stuff like that. Sounds like you already addressed the water pump and thermostat which would be the first simple things to check. Gotta be careful when they are getting hot like that because with air in the system your gauge may not read correctly and the engine could be getting hotter than you think.

 

Pressure test with something like a Standt tester, pump the system up to 23 psi and see if any pressure bleeds off over 2 minutes.