51. Engine Overheats
Probable cause
Possible remedy
a. Low coolant level.
Fill radiator and check for leaks.
b. Obstructed or broken water
Flush cooling system (par. 80). Re-
hose.
place hose (par. 86).
c. Radiator shutters do not open
Adjust shutterstat (par. 189). See
or close.
Note in paragraph 48.
d. Clogged radiator.
Flush cooling system (par. 80). Clean
radiator fins.
e. Obstructed water jackets.
Flush cooling system (par. 80).
f. Partly closed choke valve.
Push choke control button in.
g. Improper fuel mixture.
Adjust carburetor (par. 77). Blow out
air cleaner (par. 76).
h. Improper ignition timing
Check timing with timing check light
i. Diluted oil.
Change crankcase oil (fig. 16).
j. Improper lubrication.
Check against Lubrication Order
5-5065 (fig. 16).
k. Overload.
Check load against operating capacity.
52. Engine Does Not Develop Full Power
Probable cause
Possible remedy
a. Improper fuel mixture.
Adjust carburetor (par. 77). Blow out
air cleaner (par. 76).
b. Improper ignition timing.
Check timing with timing check light
c. Obstructed exhaust line.
Place a few drops of oil on weather cap
hinge (fig. 16).
d. Loose governor levers.
Tighten or replace as necessary
e. Fouled spark plugs.
Remove, clean, adjust, and replace
f. Defective distributor.
Clean and adjust points (par. 95).
Check condenser and coil. Replace as
necessary (pars. 200 through 204).
See note in paragraph 48.
g. Oil too thin.
Change crankcase oil (fig. 16).
h. Leaking spark plug gaskets
Replace gaskets (par. 96).
i. Leaking cylinder head gasket.
Tighten head nuts (par. 122). Replace
gasket if necessary (par. 122).
j. Improper valve clearance.
Adjust (par. 121).
k. Worn valve seats.
Grind valves and inserts (par. 122).
Replace if necessary.
l. Sticking or worn piston rings.
Replace (par. 233). See note in
m. Weak valve springs.
Replace (par. 122).
n. Worn pistons.
Replace (par. 223). See note in
o. Worn cylinder sleeves.
Replace (par. 225). See note in
52
53. Engine Knocks
Probable cause
Possible remedy
a. Lack of oil.
Add oil to FULL mark on oil-level gage.
b. Improper ignition timing.
Adjust timing with timing check light
c. Improper valve clearance.
Adjust valve to rocker arm clearance
d. Worn pistons.
Replace (par. 23). See note in para-
graph 48.
