Radiator cap experts

Oct 9, 2008
1,742
Bristol 29.9 Dana Point
During last run, the 15 psi cap on the exhaust manifold spit about a pint through the relief hose into the recess between the engine mount stringers, which is apparently the containment area for such an event. Also found coolant near the cap.
Engine never went above normal temp.
Removed cap. Looks new. Rubber is fabulous. Spring has great tension. Good build quality. Top of cap looks like the thing might be original 1984.
There is a remote expansion tank above the water heater. That’s where you fill. That cap is 7lb. No leaks or spewing.
Is it the manifold cap, regardless of appearance? Without your being able to look at it, of course :)

Universal M18.
 
Last edited:
Feb 10, 2004
4,154
Hunter 40.5 Warwick, RI
FWIW, I had a heat ex-changer cap (ie, radiator cap) that visually looked fine. It was NOT the OEM unit, but a aftermarket "equivalent". It began to leak similar to what you describe. USA Volvo sources wanted between $85-150 for this cap!!- you can see why I replaced years ago with a aftermarket unit. So I then found out about a source in the UK and bought the exact OEM unit for $15. Leaks stopped.
Lessons learned- you can't tell the integrety of a cap by looking at it. And "some" OEM parts work better. And Volvo is descended from pirates.