overheating and boiling water

[Fairlady300zx]

SO THE CAR IS A NISSAN 300ZX VG30DETT 3.0 STOCK NOTHING DONE TO IT JUST ITS REGULAR TUNE UP AND TIMING DONE TO IT ONLY HAS 96,156 MILES ON IT. ONLY HAVE HAD CAR FOR ABOUT 6 MONTHS I BOUGHT IT FROM A MECANIC FRIEND THAT DID NOT KNOW WHAT HE HAD SOLD IT TO ME FOR $600. SO MY PROBLEM IS THAT THE CAR IS OVERHEATING AND WHEN I SHUT HER OFF THE COOLANT IN THE OVERFLOW TANK STARTS TO BOIL AND STEAM COMES OUT THE OVERFLOW TANK TOO. I HAVE REPLACED FAN CLUTCH, WATER PUMP, THERMOSTANT, BLEED SYSTEM, AND CHAGED ALL BELTS TO IT. AND STILL THE SAME WHAT COULD IT BE IM THINKING BLOWN HEAD GASKET. IF IT IS I HAVE NEW PARTS FOR HER ALREADY BUT JUST NEED SOME INPUT THANK FOR ALL YOUR ANSWERS.

[nissanfreak12]

Change your radiator cap.

When does the car overheat? When Idling? Driving? Sitting in traffic? Have you changed the coolant? Needs to be 50/50 so doesnt freeze, lubes seals, and also raises the boiling point. Do not run straight water, it will rust and boil at a much lower temp. Your radiator cap keeps pressure in the system so it will also raise the boiling point. If it lets air in, the boiling point drops dramatically. I think its 3° per lbs.

You can also test the coolant to see if you have a head gasket issue. Napa has test strips you can dip in the antifreezeto see what the PH levels are. Another way to check is make sure the system is full, take the cap off when cold, and let the car idle. If you have a constant stream of bubbles, may have a head gasket issue. Oil in the coolant and vise versa. That will look like a milkshake.

If all else is good and you still have issues, replace the radiator, very well could be clogged.

[Fairlady300zx]

I FORGOT TO MENSION I DID REPLACE RADIATOR AND ALL I USED WAS A 50/50 MIXTURE GREEN AND ITS GOOD ON IDLE AND FREEWAY. JUST WHEN I TURN OFF CAR IT BOIL.

[Fairlady300zx]

I HAVE NO COOLANT IN OIL AND I TRIED THE RADIATOR CAP OFF AND IT DOES HAVE BUBBLES AND SPILS OUT OF RADIATOR. AND ONCE IT HEATS UP TO NORMAL TEMP THE COOLANT STARTS TO DISAPEAR SORRY FOR MISPELL I HAVE NO LEAKS.

[nissanfreak12]

That usually means your radiator cap is bad or not the proper setting. Do you have the overflow tank attached?

[nissanfreak12]

What radiator do you have? Where did you get it?

[budget300zx]

If, its not the cap and you have an overflow tank,i would start by going to autozone and renting one of these:

http://www.autozone.com/loan-a-tools/pr ... ckfit=true

[Fairlady300zx]

I GOT TO THE BOTTOM OF THE PROBLEM IT WAS THE STUPID RADIATOR CAP I FEEL SO STUPID FOR NOT TO CHECK THAT FIRST.

[nissanfreak12]

It happens, its the most overlooked item in the cooling system. Like a gas cap with the OBDII system.