The PRD Fireball establishes a seal between the jug and the head via o-rings - not a gasket. Although o-rings are typically reusable in most applications - the o-rings on the head are considered a throw-away item, which is to say, they shouldn't be reused indefinitely.
A poor head seal may manifest itself in the following ways:
- Pressurization of the cooling system - resulting in coolant overflow from the radiator pressure cap.
- Water in the exhaust.
- Oil/fuel residue in the cooling system.
There are a few possible causes for poor head seal, see the Correcting Poor Head Seal section of this manual for more information, and a procedures to fix this issue.