15 psi radiator cap

Maintenance advice to keep your Spider in shape.
Post Reply
bsharp

15 psi radiator cap

Post by bsharp »

Have a 78 fiat 124 spider. my AutoZone book calls for a 15 psi cap, but I can only find a 13 PSI and it keeps pushing the water out--. I can get a 16 psi and would that make a difference --anyone got an idea if a 15 psi is really required
So Cal Mark

Re: 15 psi radiator cap

Post by So Cal Mark »

each lb of pressure raises the boiling point 3 degrees
User avatar
RRoller123
Patron 2020
Patron 2020
Posts: 8179
Joined: Sun Nov 13, 2011 2:04 pm
Your car is a: 1980 FI SPIDER 2000
Location: SAGAMORE BEACH, MA USA

Re: 15 psi radiator cap

Post by RRoller123 »

Mark, that is interesting, Do I assume then that a 15psi cap raises the boiling point from 212 to ~257? I.e. is the relationship roughly linear?

Pete
'80 FI Spider 2000
'74 and '79 X1/9 (past)
'75 BMW R75/6
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/STD BED
2002 Edgewater 175CC 80HP 4-Stroke Yamaha
2003 Jaguar XK8
2003 Jaguar XKR
2021 Jayco 22RB
2019 Bianchi Torino Bicycle
So Cal Mark

Re: 15 psi radiator cap

Post by So Cal Mark »

yes, each lb of added pressure raises the boiling point 3 degrees. Remember, as soon as you loosen the cap and release the pressure the water will boil. If the cap keeps blowing off pressure, I'd look into a potential head gasket leak or lack of circulation
Post Reply