My 2003 sedan is overheating?

[Jons_G35_sdn]

last night after visiting a couple of stores i was headed home and noticed the temp gauge going up little by little and finally had to pull over at one point cause it was really high. I let the car sit for about five minutes then turned the heater on full turned the car on and drove temp whent back to normal and didnt go up anymore, only if i turn the heater off then it starts going up again what could it be? Also the electric fan that comes on when the a/c is on was on last night as soon as i start the car even though the a/c is off? Its a 2003 G35 sedan completely stock. UPDATE: the car is still overheating but only when i drive it, today i went out and left it on for about twenty minutes and it didnt over heat, then turned the a/c on and still nothing why does it over heat only when i drive it?

[Poyzinous]

odd...only overheating under driving load? weird. It seems like a pressure or internal issue. Water pump, radiator, thermostat could be bad.

[pfarmer]

last night after visiting a couple of stores i was headed home and noticed the temp gauge going up little by little and finally had to pull over at one point cause it was really high. I let the car sit for about five minutes then turned the heater on full turned the car on and drove temp whent back to normal and didnt go up anymore, only if i turn the heater off then it starts going up again what could it be? Also the electric fan that comes on when the a/c is on was on last night as soon as i start the car even though the a/c is off? Its a 2003 G35 sedan completely stock. UPDATE: the car is still overheating but only when i drive it, today i went out and left it on for about twenty minutes and it didnt over heat, then turned the a/c on and still nothing why does it over heat only when i drive it?

I think I would replace the thermostat and remember to test the new one prior to installation. You may need to do a cooling system flush as well in case you have some pluggage someplace. Any excess amount of steam coming out of the exhaust or an excessive action in your overflow tank?

Perry

[tollboothwilley]

I'd change the coolant and the thermostat. If the problem continues it might be your water pump.

[Jons_G35_sdn]

im taking it in today at noon to get checked out, no extra steam coming out that was one of the first things i checked, i remember when my 240's head gasket whent bad there was alot of steam coming out the exhaust. Over flow tank is fine when it gets hot it never over flows and spills or anything like that. Im going to tell them to replace the thermo and flush the system hopefully thats it. Thanks for your input guys.

[pfarmer]

im taking it in today at noon to get checked out, no extra steam coming out that was one of the first things i checked, i remember when my 240's head gasket whent bad there was alot of steam coming out the exhaust. Over flow tank is fine when it gets hot it never over flows and spills or anything like that. Im going to tell them to replace the thermo and flush the system hopefully thats it. Thanks for your input guys.

The reason I asked about the overflow tank was the comment about the waterpump. One item that can fail on a water pump is the shaft seal. While they will often leak outward that is not always the case. The eye of a centrifugal pump is often the lowest pressure area of the pump and in the case of a water pump in a car this is also the location of a shaft seal. Under high loads and/or high rpms this seal can leak air into the system even though it may not show itself by leaking coolant out. The result may then show up in the tank.

If the water pump on the 'G' is timing chain driven you may not be able to see the seal if it leaked outward anyway. How is the oil level?

Perry

[Jons_G35_sdn]

oil level is fine. I took the car to get the thermo stat replaced and coolant flushed and hasnt overheated again so far. It was still the original thermostat so its about 7 years old. Thanks again guys for your time and input!

[tollboothwilley]

Just sounds like a thermostat was sticking. That would explain the periodic overheating temps.

Hopefully that is all it was and all is resolved now.

[pfarmer]

oil level is fine. I took the car to get the thermo stat replaced and coolant flushed and hasnt overheated again so far. It was still the original thermostat so its about 7 years old. Thanks again guys for your time and input!

Sounds like you are back in business. In this case my question about oil level was not in reference to a head gasket leak which is probably the normal direction the question would be pointing at. Rather it was a question about the water pump on a car which has a timing chain. I am not familiar with how the 'G' is setup for the water pump drive, so not sure exactly how relevant this may be, but on many with a timing chain driven water pump versus a timing belt driven water pump (many Hondas) a leaking seal can show up as water in the oil. Scares the hell out of you since your first thought may be towards the worst situation. It is often recommended that if you ever do have any reason to be in this area of your engine that you automatically replace the water pump.

Perry

[Joey666Crack]

=UPDATE: the car is still overheating but only when i drive it, today i went out and left it on for about twenty minutes and it didnt over heat, then turned the a/c on and still nothing why does it over heat only when i drive it?

So when you don't drive your car, it doesn't over heat... Makes sense.

[pfarmer]

So when you don't drive your car, it doesn't over heat... Makes sense.

I don't think the car was every overheating. Now the engine when it is running just might.

Perry

[Joey666Crack]

I'm glad someone else noticed the logic or lack there of behind that sentence. Thanks Perry.