1999 Volvo Penta "WT" Models Workshop Manual, Page 270Get this manual
Hydraulic Valve Lifter Checking Hydraulic Valve lifter
When checking hydrau lie valve lifters, remember that grit, sludge, varnish, or other foreign matter will seriously affect their operationIf any foreign substance is found in the lifters or engine where it may be circulated by the lubrication system, thorough cleaning job must be done to avoid repetition of lifter troubleTo help prevent lifter trouble, the engine oil and oil filter must be