Overheating issue

[BHP231]

So, other than blowing the motor (see thread what did you do to your car today?) I have an overheating issue.
All seems fine until the coolant boils through the relief valve.
Engine temp gets hot, then the fans kick in and the temp comes down, then goes up, fans come on, etc.
Any thoughts on how to fix this coolant boiling over problem?
Thanks.

[Ga 951]

The symptoms sound like air in cooling system. Sometimes these cars are hard to get all the air out of the system as indicated by copious amount of posts regarding the issue.

If you haven't done so, start there.

[flashx]

Check the radiator cap. When they go bad they will let the coolant boil

[porschetub]

Originally Posted by Ga 951

The symptoms sound like air in cooling system. Sometimes these cars are hard to get all the air out of the system as indicated by copious amount of posts regarding the issue.

If you haven't done so, start there.

Once I had this issue and the air wouldn't clear,got a good tip of this forum,park the car on a hill nose up and run with heater on,after days trying to sort it this fixed it straight away.

[v2rocket_aka944]

bleeding a 944 is dead simple...
1) apply water to empty coolant system, leave rad cap off
2) jack nose of car as high off the ground as you can, at least 12"
3) open heater core to max
4) open bleeder screw so that hole is fully exposed
5) start car, let it run/idle until it gets to temperature
6) continue adding water to expansion tank as necessary to keep water line at "full"
7) leave car running 10-20 more minutes, eventually steam and then straight water/coolant will be pissing out of the bleeder screw...have lots of paper towels handy
8) close bleeder screw and put car on ground, verify coolant level, drive...

[BHP231]

Thanks all. I already replaced the coolant cap. Will bleed radiator and do a general check while motor is out, then do the recommended checks when the new motor goes back in.

[thomasryan]

See if your cap matches the specifications.

Check this but the early caps are 100kPa and the big motors take a 150kPa. My temps where creeping up so I tested a bit. my cap is only holding 75% and the cap is two years old. (Only holding 15psi instead of 22psi) I threw on a spare 140kPa and the temps came down.


It's so hot on this side of the globe, I have melted the capacitors in two amps in the mercs))