66.
Exhaust Becomes Smoky
Possible remedy
Probable cause
Refer to LO 5-1185 and fill the crankcase with proper
Oil too thick.
grade of oil
Adjust oil pressure relief valve (par. 197d). See note in
Oil pressure too high.
Check and maintain proper oil level.
Oil level too high.
Replace piston rings (par. 178l). See note in paragraph
Pistol rings worn or broken.
Rebore cylinders (par. 181). See note in paragraph 55.
Cylinder bore out of round.
Adjust carburetor (par. 106d).
Carburetor out of adjustment.
67.
Engine Lacks Power
Possible remedy
Probable cause
Check compression. If the pressure varies more than 10
Compression faulty.
lb. between the cylinders, engine overhaul will be
needed. See note in paragraph 55.
Adjust valve timing (par. 182l). See note in paragraph
Valve timing incorrect.
Adjust carburetor (par. 106d).
Carburetor out of adjustment.
Adjust throttle valve (par. 108d).
Throttle valve not fully opening.
Clean fuel lines (par. 104).
Dirt in fuel lines.
Replace manifold gasket (par. 132).
Air leak in the manifold gasket.
Inspect and correct source causing overheating
Overheating.
Clean carbon (par. 135).
Preignition, caused by carbon deposits
Grind or replace valve seats (par. 177). See note in
Valve seats leaking.
Replace piston rings (par. 178). See note in paragraph
Piston rings broken.
Adjust valve-tappet clearance (par. 136b).
Valve-tappet adjustment incorrect.
Clean air cleaner (par. 105d).
Air cleaner clogged.
Clean or replace exhaust pipe and muffler (par. 133).
Adjust magneto (par. 116).
Magneto out of adjustment
Tighten spark plugs or replace gaskets (par. 117).
Spark plugs leaking.
68.
Cooling System Leaks
Possible remedy
Probable cause
Repair or replace (par. 129).
Radiator core leaking.
Tighten clamps or replace hose (par. 129).
Hose connections defective.
Repair or replace water pump (par. 130).
Water pump leaking.
Replace cylinder head (par. 135).
Cylinder head cracked.
Replace cylinder head gasket (par. 135).
Cylinder head gasket blown.
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