LO 11-8 Outline maintenance procedures and identify tools and methods used to perform maintenance on a diesel engine cooling system

1.15. Radiator Cap Inspection

Radiator Cap Inspection
The rubber gasket that seals the pressure valve at the bottom of the radiator neck should be inspected. Cracked, deteriorated, or damaged gaskets will leak, and caps with such gaskets should be discarded. When pressure testing cooling systems, the radiator cap should be simultaneously pressure checked. The cap should not leak until the pressure rating imprinted on the cap is reached.

The vacuum valve spring should also hold the vacuum valve closed when the cap is removed and no pressure is applied to the cap. A dangling vacuum valve observed when the cap is removed is evidence of a defective vacuum valve.