Inspection of Cylinders for Scuffing

h. Lubricating Oil Pressure Outlets.

(7) Add oil as required to bring oil in oil pan

Lubricating oil pressure outlets are provided in

to full level as indicated on oil level gage,

t h e main and piston oiler nozzle gallery lines for

carefully measuring amount added.

i n s t a l l a t i o n of pressure sensing gages to measure

(8) Maximum allowable oil consumption at

2400 rpm, with SAE 30 oil, is 0.0075 pounds

t h e engines oil pressures (para 8-1i, (1) and (2)).

i. Induction Air Temperature. An outlet is

per brake horsepower hour (lbs / bhp / hr).

provided in the bottom of the intake manifold,

g. Checking Exhaust Gas Temperature. P i p e

on each side of the engine, for installation of

plugs (4, fig. B-12) are provided in exhaust

thermocouples to measure induction air tem-

manifold elbows for installation of ther-

mocouples to measure exhaust gas temperatures

perature (para 8-1j).

j . Manifold Pressure. An outlet is provided in

(para 8-1f). Variations of temperatures between

cylinders should not exceed 150F. Check fuel

t h e intake manifold elbows, on each side of the

injector nozzles of cylinders that exceed this

engine, for installation of a manometer gage

variation.

and / or connection (para 8-11).

Table 8-1. Overhaul Test Schedule-Beam Length...1.75 Ft.

(or 21.008 in.)

Scale limits

Obs. BHP

RPM

Torque Lh-Ft.

Time Min.

Run No.

Warm-up

700

16.0

1000

16.0

438

83.5

116.9

1400

1800

159.5

287.1

837

429.0

1024

2200

195.0

208.0

499.2

1092

2400

549.6

1202

2400

229.0

F.R. - F.L.

2400

F.R. - F.L.

Check for low idle at 675 to 725 rpm. Adjust if necessary.

C h e c k oil filter and inspect for oil and fuel leaks.

2200

F.R. - F.L.

2000

1800

F.R. - F.L.

Check governor high idle speed. This shall not exceed 2640 rpm,

(No-Load, water off). If adjustment is required, recheck horsepower

at 2400 full load.

Borescope cylinders (para 8-6), check for fuel and oil leaks, prepare

engine for removal from stand.

result of one or more conditions such as;

Note. Run numbers 1 through 8, and 11

t h r o u g h 14, shall equal three hours. Sequence of

a b r a s i v e s in the oil or induction air, lack of or

i m p r o p e r honing, defective piston ring, etc. The

operations may be varied.

heat and pressures involved during the scuffing

8-6. Inspection of Cylinders for Scuffing

process will flow or smear the cylinder wall metal

a. G e n e r a l .

and destroy the honing pattern. The process in

(1) As used in this publication, cylinder wall

g e n e r a l generates additional heat due to friction

"scuffing" is defined as a streak or streaks,

a n d in many cases the scuffing will progress or

r u n n i n g the length of the piston ring travel, on

the width of the afflicted area will grow and may

the cylinder wall, which are greater than 1 / 4

envelope the entire cylinder bore. Scuffing is

inch wide and which reveal a high gloss or polish

d e t r i m e n t a l to the engine, since oil consumption

w h e r e the cylinder wall honing pattern has been

a n d blow-by gases can no longer be controlled.

completely worn away.

b. Borescope Inspection.

(2) Scuffing is caused by excessive localized

(1) After completion of dynamometer in-

h e a t on the contact face of the piston ring and

spection, all overhauled engines s h a l l h a v e

cylinder bore. The excessive heat is due to a

cylinders inspected by borescope as follows:

b r e a k d o w n of the oil lubricating film and is the

8-7