22-3
CHECKING COMPRESSION PRESSURE (Continued)
B. RUNNING 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
i!:~SEMBLV
~-
LJ SPACER
COMPRESSION ADAPTER
70-314 (D-558)
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 indicated, 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)
IGINALCLAMPASSEMBLY
AND SPACER
VENT BUTTON
I
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
L 1--- 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.
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