WARNING: With cooling system tester in place, pressure will build up fast. Excessive pressure built up, by continuous engine operation, must be released to a safe pressure level. Never permit pressure to exceed 138 kPa (20 psi). Failure to follow this warning may result in serious or fatal injury.
Install Cooling System Tester (special tool #7700, Tester, Cooling System) or equivalent to pressure cap neck. Start the engine and observe the tester’s pressure gauge. If gauge pulsates with every power stroke of a cylinder a combustion pressure leak is evident.