: Rad Cap PSI was wrong

08-04-09, 07:12 PM
I wanted to replace my rad cap and found out when I was at the dealer that the cap was suppose to be 18 PSI and my car had 15 PSI cap
I hope that this has not done any damage.
What do you guys think??


08-04-09, 07:58 PM
No damage done - just that the 15# cap would have allowed the coolant to boil at a slightly lower temp than designed.

At 18 psi a 50/50 mix of DEXCOOL/distilled water boils at 265 and a 70/30 mix (GM recommended maximum) boils at 276. 16 psi is a few degrees cooler for boil points.

ALWAYS check the cap sticker, not the box, when buying a coolant tank cap at a parts store - you can easily wind up with 15, 16, 18, whatever from people swapping caps and boxes. Happens all the time.

08-06-09, 09:32 AM
What he said, it won't hurt anything... unless you use an improper coolant mix and end up stuck in traffic.
Just make sure the right one is on it now.