LOSS OF COMPRESSION.

Franklin Times, Volume XIX, Issue 138, 27 November 1929, Page 7

LOSS OF COMPRESSION.

Loss of compression will cause the engine to lose power or will make it difficult to start, but will not cause sudden stopping. However, it should be immediately attended to. To locate defective cylinders, open all pet cocks or remove all spark plugs. Test the compression of each cylinder in turn by closing its pet cock or inserting the spark plug and cranking throughout by hand. Valve tappets set too close: See that the tappets are free when valves are closed. Adjust clearance when hot to clearance laid down in maker's instruction book.

Valves may be carbonised or pitied: Grind the valves, and if they are warped, replace them.

Valve stems gummed or stuck: Free with denatured alcohol or kerosene. If a valve stem is bent when removing, replace with a new valve.

Valve spring weak or broken: Look for flattened or broken coils. Fit new springs.

Spark plug or valve covers leaking: Listen for hiss or cover with oil and watch for bubbles. Tighten or replace, using new gasket. Lubricating oil badly diluted or of incorrect grade: See if the engine cranks stiffly when hot or lacks compression on all cylinders. Drain and refill with the correct grade of oil. Piston-rings and cylinders worn: Engine smokes badly at breather or oil filler opening. Compression leaks can be heard when the engine is run slowly under load or when cranked by hand. Cylinder head gasket leaking or blown out: Look for water on spark plug points and .for leaks around the head. Fit a new gasket, and tighten the head bolts evenly.