Harley Davidson Model WLA (motorcycle, solo). Service manual (October, 1943) - page 3
TROUBLE SHOOTING
с. Red Signal Light Continues to Burn After Engine Is Operated Above
Idling Speeds
(1) Check oil supply in tank. If light fails to go out after engine is
warm, or after 1 minute of operation, further checks must be made to
locate trouble, as indication points to faulty engine lubrication
system, or fault in signal circuit. Eliminate the signal system first.
(2) Test oil pressure signal switch to panel signal light circuit.
Remove wire from oil pressure switch terminal by turning on ignition and
light switch and observing red signal light. If light bums, short
circuit in wiring exists. If light does not burn, it indicates normal
condition, leaving oil pressure switch of the signal circuit to be
tested.
(3) Install new oil pressure switch and start engine. If red signal
light goes out after engine is operated above idling speeds, it
indicates trouble in oil pressure signal switch. If red signal light
continues to burn, it indicates trouble in oil feed pump. Replace pump
(par. 44),
Excessive Smoke Issues from Exhaust and Oil Spray
Issues from Gear Case Breather Outlet. This is an indication that the
scavenger pump is not draining engine crankcase and returning oil to
tank. With engine running at idle speed, examine oil return in tank.
Remove tank oil cap, and with a small flashlight (tactical situation
permitting), observe whether or not oil is dripping from 1/8-inch hole
in oil return tube. Hole is on under side of tube and is located just
back of oil gage rod tube. If observation is poor, place finger over
hole and feel for pulsation of oil pressure. If oil does not return to
tank, scavenger pump is faulty. Should the crankcase breather valve be
incorrectly timed, smoke will issue from the exhaust, but not as
noticeably as when scavenger pump is not working. Refer to step e below
for this condition.
e. Smoke Issues from Exhaust and Excessive Oil Condition Exists Around
Cylinder Exhaust Ports (where exhaust pipes enter cylinders), Engine
scavenger pump and crankcase breather valve are one unit, operated by
worm gear located behind engine shaft pinion gear. Although scavenger
pump is not "timed/' the . breather valve sleeve which drives it must be
timed to balance the engine lubricating system. If for any reason the
scavenger pump unit is removed from engine base, the breather valve must
be retimed (within the gear case) when pump assembly is replaced.
Incorrectly timed breather valve will force oil past piston rings,
causing some smoke, besides forcing oil out through exhaust ports,
causing excessive oily condition around exhaust pipes where they enter
cylinder ports.
31. FUEL SYSTEM.
a. Many symptoms which might be attributed to the air-fuel system are,
in reality, due to faulty ignition. Before attempting any