OK, I Love my 2003 G35 which I just purchased about 3 weeks ago- except for ONE BIG PROBLEM. The car overheats!!!

Have had 2 shops look at it and say they've fixed it, then after a short time it overheats again. I finally threw my hands in the air, gave up and went to the stealer. They told me it was the aftermarket thermostat which I had installed, changed it our for an OEM thermostat and burped all the air out.. I drove it around for several hours and was really happy that it stayed in the normal zone and declared it finally FIXED!!!!

The next day, my wife drove the car on a 700 mile trip by herself to visit relatives in another state- Couldn't talk her out of driving it! So she does great for the first 6 hrs, then.... she calls me from the middle of nowhere and you guessed it- OVERHEATING AGAIN!! She's able to add some coolant and nurses it into her final destination.

Next day takes it to a highly recommended shop. They claim it's just air in the system, burped it and gave it back to her. Worked great for 1 hr. Now still overheating @#@%$&!! Took it back, and now they too are scratching their heads!!!!

OK, here's what the symptoms are- Temp rises, Coolant is pushed into reservoir, air is in the system (heater blows cold) Tech says the pressure in the system goes up to 20 psi, when you first start the car, then drops to 10-12 psi.

Here's what has been done to the car. New thermostat, new radiator cap, Thoroghly bled system by the dealer, Block leak test, cylinder compression test, vacuum AND pressure tested cooling system. No leaks anywhere!

I'm beginning to feel like giving up.. getting VERY ANNOYED. Seems like no mechanic, no matter how experienced can explain this dilemma!

Any help with your suggestions would greatly be appreciated!!!!

 

It can take an hour or more to properly purge the air from the system.

 

I agree with air in the system. If you have to add fluid and there are no leaks there must be air in tge system. Spend a day thoroughly burping the system.

 

i had to add a cup of coolant to the reservoir daily for a week after my coolant change (the car wasn't overheating or anything, but i guess there was air in there)..

 

Have a shop lift the front end up a little (leaving rear on the ground) and let it run for a while to get all the air out.

 

a really steep incline is what you need to bleed the system.... like 30 degrees parking ramp kind of steep.

 

The car has already been jacked up way high in front. Maybe I need to tell them to use that special radiator funnel?? I'm assuming that a pretty thorough job of burping was done at the dealer, in fact after they did it, it lasted the very longest without overheating (6 hrs) as compared to the other shops (and my own attempts as per Nissans shop manual. I just think there's air somehow getting into the system... I think I will have the shop try the burping several more times. I will let you all know the results!! Thanks for your responses!!!

 

A Lisle funnel will help with bleeding the system, check online for one, I got mine for under $30 shipped. Handy to have around and much cheaper than bringing it back to the dealer.

Was the new rad cap an OEM or aftermarket one? My friend with an Maxima just had to return an aftermarket rad cap 3 times before getting one that worked properly instead of going to Nissan like I said and buying an OEM one like I did. His wasn't allowing coolant to be drawn back into the system, allowing bubbles to form in his lines and causing his heat to blow cold.

 

Interesting.. This may be my problem!!! I don't recall mine drawing the overflow coolant back into the radiator. Going to buy an OEM cap from Nissan and then bleed the air out of the system like crazy... I'll post results as soon as I do this.

 

I had the same problem that you have described, your head gasket is done. You will need to rebuild the top part of your engine.

 

I was thinking that too..

 

But in the description he says the car passes leak down and compression test....?

 

What about the block tests we did?? No CO in the coolant either. Compression all over 150.

I'm hoping you're wrong, but certainly know it's a possibility.

 

Mine had no leaks whatsoever, overflow was bubbling and had white smoke coming out of the tails. Mind you, the white smoke was a one time thing. We thought condensation, wrong. It was a blown head gasket, because the engine rebuilder did not know how to bleed the air out of the coolant system.

So, we had to rebuild the engine, again.

 

There are two indications of a blown head gasket, oil in the radiator or water dripping out the tail pipe. If all the tests he listed were done correctly you can ignore the head gasket issue. When I was stumped a good radiator shop always had the answer after dealerships replaced everything in sight! Can we assume they checked the fans, if and when they came on?
Gary