35
4-CYCLE ENGINE TROUBLESHOOTING CHART (Cont.)
Cause Remedy and Reference
ENGINE USES EXCESSIVE AMOUNT OF OIL
Engine speed too fast. Using tachometer adjust engine RPM to spec.
Oil level too high. To check level turn dipstick cap tightly into receptacle for
accurate level reading.
Oil filler cap loose or gasket damaged causing Replace ring gasket under cap and tighten tube securely.
spillage.
Breather mechanism damaged or dirty causing Replace breather assembly.
leakage.
Drain hole in breather box clogged causing oil to Clean hole with wire to allow oil to return to crankcase.
spill out of breather.
Gaskets damaged or gasket surfaces nicked Clean and smooth gasket surfaces. Always use new
causing oil to leak out. gaskets.
Valve guides worn excessively thus passing oil Ream valve guide oversize and install 1/32'’ oversize valve
into combustion chamber. and new valve seal if equipped.
Cylinder wall worn or glazed, allowing oil to Bore cylinder for oversized piston & rings.
bypass rings into combustion chamber.
Piston rings and grooves worn excessively. Reinstall new rings and check land clearance and correct
as necessary.
Piston fit undersized. Measure and replace as necessary.
Piston oil control ring return holes clogged. Remove oil control ring and clean return holes.
Oil passages obstructed. Clean out all oil passages.
Breather tube not connected to air cleaner. Reconnect tube.
Using 10W30 oil under high load/high temperature Replace with SAE 30 oil.
conditions.
OIL SEAL LEAKS
Crankcase breather plugged. Clean or replace breather.
Seal/Main brg drain hole plugged. Clean out hole.
Old seal hardened and worn. Replace seal.
Crankshaft seal contact surface is worn undersize Check crankshaft size and replace if worn excessively.
causing seal to leak.
Crankshaft bearing under seal is worn excessively, Check crankshaft bearings for wear and replace if
causing crankshaft to wobble in oil seal. necessary.
Seal outside seat in cylinder or side cover is Visually check seal receptacle for nicks and damage.
damaged, allowing oil to seep around outer Replace P.T.O. cylinder cover, or small cylinder cover on
edge of seal. the magneto end if necessary.
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