Section XV. ENGINE TESTING

tortion, and worn mounting holes; replace a damaged

drive plate.

(3) Remove the setscrew (3) that secures the

coupling half (7) to the pump shaft; remove the coupling

half and key.

(6) Inspect all other parts for cracks, distortion, and

(4) Remove the lock wire (4) and the

other damage; replace damaged parts.

retaining ring (5) that secure the collar (6) to the

coupling half; remove the collar.

c. Reassembly and Installation.

(5) Remove the cap screws (8) and lock

washers (9) that secure the drive plate (12) to the

(1) Position the coupling half (13, fig. 440)

engine flywheel; remove the assembled coupling half

on the drive plate (12); secure with six cap screws (10)

(13) and drive plate.

and lock washers (11).

(2) Position the assembled drive plate and

(6) Remove the cap screws (10) and lock

coupling half on the engine flywheel; secure with eight

washers (11) that secure the coupling half (13) to the

cap screws (8) and lock washers (9).

drive plate (12); remove the coupling half.

(3) Position the collar (6) on the coupling half

(7); secure with the retaining ring (5). Make sure the

retaining ring is fully seated in the ring groove and install

b. Cleaning and Inspection.

the lock wire (4) in the retaining ring.

(4) Position the assembled coupling half (7)

(1) Clean the six cushions by wiping them

and collar (6) on the end of the pump shaft so that the

with a clean, dry cloth.

keyway engages the key on the shaft. Secure with the

(2) Wash all remaining parts with cleaning

setscrew (3).

solvent (fed. spec. P-D-680) ; dry thoroughly.

(5) Install three cushions (2) on each coupling

(3) Inspect the cushions for cracks, wear,

half; secure each with a sleeve (1).

brittleness, and deterioration; replace damaged

(6) Install the pump on the engine and skid

cushions.

(para 4-47c).

(4) Inspect the coupling halves for cracks,

worn teeth, worn bores, damaged threads, and other

damage; replace damaged coupling halves.

(5) Inspect the drive plate for cracks, dis-

Section XV. ENGINE TESTING

4-49. General

between 180 and 200 F.

Failure to reach this

Engine testing at organizational maintenance level

temperature indicates that the thermostat is faulty.

includes an operational test and a cylinder compression

Temperatures above this range indicate either a faulty

check. Close observation of the engine while operating

thermostat, clogged or dirty radiator, scale buildup in the

under load plus a compression check which indicates

block or head, damaged water pump, improper ignition

the condition of the valves, piston rings, and pistons, will

timing, or a faulty lubrication system which is allowing

provide fairly comprehensive information regarding the

excessive friction in the interior of the engine.

condition of the engine. This can be accomplished

without the use of any specialized tools other than a

c. Check the oil pressure on the oil pressure gage.

compression gage.

Perform all daily preventive

At governed speed, the oil pressure must be between 20

maintenance services before testing the engine.

and 30 psi. Low oil pressure indicates low engine oil

level, clogged screen on the engine lube oil pressure

4-50. Engine Operational Test

pump, faulty lube oil pump, or improper setting of the oil

Caution: Make sure pump is primed before starting

pressure relief valve. High oil pressure indicates a

engine. Running pump dry may damage shaft seal.

clogged oil passage or an improperly adjusted oil

Refer to paragraph 2-8a(2).

pressure relief valve.

d. Check the indication of the ammeter. After an

a. Start the engine. The engine starter should turn

initial high charge rate, the ammeter must remain close

over the engine freely and easily. The engine must start

to the midposition, just slightly to the charge side. A

without excessive cranking.

Run the engine long

high charge rate indicates a faulty battery, shorted or

enough to warm it to operating temperature.

grounded connection, high resistance connection, or a

b. Check the operating temperature on the engine

faulty regulator setting.

coolant temperature gage.

It must stabilize

4-45