Case W9 - Page 24

22-3
CHECKING COMPRESSION PRESSURE (Continued)
B. RUNN ING METHOD - Disconnect the
high pressure fuel line and leak-off lines
from number one injector. Using an
appropriate length of tubing or hose,
route the fuel from these lines back to
the fuel tank or a clean container . Re-
move the number one injector. Refer to
chart below .
4.
Clean the injector bores of loose carbon
and residue. Replace the compression
seal in the injector bore of the cylinder to
be checked and install a Bacharach 70-314
(D-558)Compression Gauge Adapter, Fig-
ure 1. Secure with an original injector
clamp assembly and spacer. Figure 1, In-
set A. Tighten bolt to 20 foot pounds.
Connect Case No. CD-504 Compression
Gauge to the adapter, Figure 2.
IMPORTANT It is very important that
all cylinder pressures be approximately
alike . For the allowable compression
pressure variation, refer to chart below.
INSET A
~~SEMBLY
~-
LJ SPACER
COMPRESSION ADAPTER
70 - 314 (D-558)
Figure 1
5.
If the compression is greater than the
figure mentioned, carbon deposits are in-
dicated . If the reading is below these fig-
ures, leaking valves or excessive ring
clearance is indicated. NOTE To make
a simple check when a compression leak
ENGINE
SPEED
is indicat e d, squirt a small amount (a tea-
spoon) of oil into the cylinder and recheck
the compression. If the pressure rises to
near normal, compression loss is past the
rings . Very little change in compression
indicates leakage past the valves. A low
pressure reading will cause difficulty in
starting particularly at low temperatures .
NOTE Take several compression read-
ings on each cylinder. This is done by
pressing the vent valve button, Figure 2,
to relieve gauge pressure. When the but-
ton is released the gauge will again in-
dicate compression pressure.
COMPRESSION ADAPTER
70-314 (D-558)
VENT BU~~
I
""-- CD504 COMP~ESSION GAUGE
Figure 2
IMPORTANT Replace the compression
seal and carbon seal on all injectors at
the time of installation, Figure 3.
CARBON SEAL
't--- COMPRESSION SEAL
Figure 3
NORMAL
ALLOWABLE
COMPRESSION
VARIATION
PRESSURE
BETWEEN
CYLINDERS
CRANKING
Approximately 200 RPM 400 PSI*
25
PSI
RUNNING
. 800
RPM
480 PSI*
20 PSI
NOTE * A 4% reduction in PSI must be allowed for every 1000 ft. above sea level.