Cylinder Head; Prepare Cylinder Head For Removal; Pre-Setting Regulator; Setting Tester - Columbia ParCar P4G Service Manual

Caution: Injury may occur if the crankshaft is not
positively locked from rotating. The air pressure
can create a rotational force of up to 60 ft. lbs. (70
kg/cm, kp/cm81.4 Nm) if the crankshaft is not
locked with the piston at top dead center.
5. Pull regulator lock nut out and turn adjustment knob
counterclockwise as far as it will go, Figure 83.
Regulator Lock Nut
& Adjustment Knob
Counterclockwise
Figure 83 - Pre-Setting Regulator
6. Connect tester to the shop air source (minimum air
pressure of 70 psi. (49.2 KG/cm2).
7. Install outlet hose into spark plug hole of cylinder
being tested. Be sure O-Ring is seated to prevent air
leak at spark plug hole. Connect other end to tester.
8. With breaker bar held securely, slowly turn regulator
adjustment knob clockwise until tester's inlet gauge
needle is on the set point. Push in regulator lock nut.
Note position of outlet gauge needle, Figure 84.
Inlet Gauge
Set Point
Regulator
Adjustment
Knob
Figure 84 - Setting Tester
Note: Any air leaks at connections or fittings of tester will
affect the accuracy of test.
9. Listen for air leaking from cylinder head gasket, car-
buretor, exhaust system and either crankcase
breather or high oil fill dipstick tube.
Note: If a high flow of air is leaking from exhaust and car-
buretor, make sure that piston is at TDC on compression
stroke.
Outlet
Gauge
Needle
7-35
a. Air flowing between cylinder and cylinder head
indicates that cylinder head gasket is leaking.
b. Air flowing from carburetor indicates air is leaking
past intake valve and seat.
c. Air flowing from exhaust system indicates air is
leaking past exhaust valve and seat.
d. Air flowing from crankcase breather tube or high
oil fill dipstick tube indicates air is leaking past
piston rings.
Test
Reading is Green. A
small amount of air is
leaking from head gasket.
Reading is Green,
minimum air leakage.
Reading is Green/Red or
Red, and all the air is leak-
ing from one component.
Reading is Red, and air is
leaking from several com-
ponents.
10. When test is complete, push regulator lock nut in and
turn regulator lock nut counterclockwise as far as it will
go to release pressure in combustion chamber.
11. Disconnect outlet hose from tester before removing
from spark plug hole.

Cylinder Head

Prepare Cylinder Head for Removal

Before cylinder head can be removed, external parts such
as air cleaner hose, fuel lines, oil fill tube and dipstick,
blower housing, muffler head pipe, carburetor, throttle and
choke cables, and starter/generator must be removed.
Remove Rocker Arm Cover
1. Remove four screws from valve cover.
2. Remove valve cover and breather valve assembly.
See Figure 85.
Result
Replace head gasket,
then re-test.
Look for other problems
that are not compression
related.
Look for a possible prob-
lem with that component.
Check that piston is at TDC,
on compression stroke. If
reading does not change,
look for problems beginning
with component that
appeared to leak the most
air. Re-test after repair.