Chapter 8. DEPOT MAINTENANCE INSTRUCTIONS

CHAPTER 8

D E P O T MAINTENANCE INSTRUCTIONS

Section I. DEPOT MAINTENANCE SPECIAL TOOLS AND EQUIPMENT

No special tools or equipment are required to perform depot maintenance of this test stand.

Section Il. TROUBLESHOOTING

170. General

This section provides information useful in diagnosis and correction, inspection, operation,

or failure of the hydraulic test stand, or any of its components. Each trouble symptom stated

is followed by a list of probable causes of the trouble. The possible remedy recommended is de-

scribed opposite the probable cause.

171. Engine Hard to Start or Fails to Start

Probable cause

Possible remedy

Magneto defective ------------------------------------------------------ Repair or overhaul the magneto (par. 185).

Valves defective ------------------------------------------------------- Reseat or replace defective valves (par. 186).

172. Engine Misses or Runs Erratically

Possible remedy

Probable cause

Magneto defective ----------------------------------------------------- Repair or overhaul the magneto (par. 185).

Valves burned, warped, or broken --------------------------- Grind or replace valves (par. 186).

Valve seats cracked --------------------------------------------------- Reface valve inserts (par. 187).

Compression poor ---------------------------------------------------- Replace valves (par. 186). Replace

pistons

and/or

piston rings (par. 195).

173. Engine Stops Suddenly

Probable cause

Possible remedy

Magneto defective --------------------------------------------------- Repair or overhaul magneto (par. 185).

Replace bearing and repair or replace crankshaft (par.

Connecting rod and crankshaft bearings seized due to

196) .

lack of oil.

174. Engine Will Not Idle Smoothly

Probable cause

Possible remedy

Valves burned, warped, or sticking ----------------------------- Grind or replace valves (par. 186).

Valve springs weak or broken ------------------------------------ Replace defective valve springs ( par. 186).

Piston rings worn --------------------------------------------------- Replace piston rings (par. 195).

Pistons and cylinder walls scored ------------------------------------ Rebore cylinder blocks and install oversize pistons and

rings (pars. 195 and 199).

175. Engine Knocks or Develops Excessive Noise

Probable cause

Possible remedy

Connecting rod and crankshaft bearings defective ------------ Replace worn or defective bearings (pars. 195 and 196).

Oil pump defective ---------------------- --------------------------- Repair or replace oil pump (par. 193).

176. Engine Exhaust Smokey

Probable cause

Possible remedy

Pistons and/or piston rings defective------------------------- Replace pistons and/or piston rings (par. 195).

AGO 5742A