PRD Fireball Shop Manual/Cooling

Head Seal 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.