Blow-By Check.

C2, TM 9-2815-213-34

Check oil pressure and water circulation: look leaks.

generally no reason for concern. As the rings and

(1) Apply dynamometer load to develop

cylinder liner combination wear in, the blow should come

horsepower at speed (rpm) indicated below.

down below 5 inches of water. If blow-by does not

Maximum Rated HP @ RPM-300@ 3000

decrease after 30 minutes, continue to operate for up to

Maximum Fuel Rate lbs./hr.-120

50 hours. If blow-by is not below 5 inches of water within

Maximum Crankcas e Pressue-5

50 hours of operation, the engine must be considered

Valve and Injector Settings (130 degrees/150

unacceptable.

d. Power Check.

degrees Fahrenheit)

Injector, Inch-Pounds-50

(1) Run engine ar rated speed for 5 minutes. It

Valves: Intake-14, Exhaust-27

should indicate 96 percent of rated power at standard

First h Hour HP@ RPM-75 @ 2000

fuel rate (120 pounds per hour). Check crankcase blow-

Second % Hour HP @ RPM-125 @ 2500

by.

Third % Hour HP @ RPM-150 @ 2700

(2) If crankcase blow-by exceeds value shown

Fourth Hour HP @ RPM--250 @ 3000

(5 inches of water), reduce engine speed and load to

Fifth 'i Hour HP @ RPM-275 @ 3000

preceding level. Run engine 30 to 45 minutes.

Power check 5 min. maximum 96 percent Rated

(3) Repeat procedures described above until

Power-288 @ 3000

engine develops 96 percent power (288 horsepower) at

(2) Check crankcase blow-by (paragraph

standard fuel rate (120 pounds per hour) within

below). If not excessive, reduce run-in time by one-half.

permissible crankcase blow-by limit (5 inches of water).

(3) If blow-by is too high, run engine for time

period shown under item (1) above.

CAUTION

(4) At first period only: Run the engine until

Do not exceed 5 minute power check

temperature reaches 140 degrees Fahrenheit. Add to

limitation.

bring level up to "H" mark on dipstick.

(5) At second period only: Reset valves and

(4)

During power check, check lubricating oil

injectors. Set engine governed speed and fuel rate.

as follows:

(6) At third and thereafter: if blow-by is

(a) Oil pressure at idle speed, 10 to 30

excessive, reduce load to preceding phase and run 30

p.s.i. @ 225 degrees Fahrenheit, at maximum speed,

minutes; then return to original sequence and continue

60 p.s.i., maximum. Lubricating oil pressure should

planned program.

remain at or near a constant figure at constant engine

c. Blow-By Check.

speed and load, after normal operating temperatures

(1) Install right bank rocker housing. Install

have reached.

sealed type oil dipstick.

(2) Install right bank rocker housing. Install

NOTE

sealed type oil dipstick.

Abnormally high oil pressures may

(3) Attach a manometer to the hose coupling

indicate restricted lubricating oil lines.

the checking too (fig 3-98), and fill the tube w water to

Low pressures indicate an insufficient oil

the "0" mark at the middle of scale.

sup- ply or increased oil clearance which

(4) Manometer readings must be taken

may be due to bearing wear.

frequently during the break-in test to note any blow-by

crease. If there is any increase, engine speed must

(b) Under full load conditions, oil pressure

decreased for a few minutes and then brought back

may drop to 30 p.s.i. and oil temperature may reach 250

original setting.

degrees Fahrenheit to 265 degrees Fahrenheit to 265

(5) During each 5 minute power check, keep a

degrees Fahrenheit for a short period. This is not cause

constant check on the manometer. If the press rises,

for alarm.

more run-in is required. Maximum press limits for engine

running, at governed speed a operating at 96 percent to

CAUTION

100 percent of rated horsepower are listed in paragraph

Any sudden increase in oil temperature

b (1), above.

which is not caused by loading increases

(6) Observe variation in rate of blow-by during

in a warning of possible mechanical

initial engine run. If the crankcase pressure, or blow- by

failure and should be investigated at

is greater at the end of the testing period than maximum

once.

values listed, the engine should operated at 96-100

percent rated load and rpm for minutes. If the blow-by is

not is' not increasing, although it may be above 5 inches

engine should be shut down and engine oil added to

of water (maximum crankcase pressure), there is

compensate for engine oil absorbed by filters.

3-61