TOPIC:
IDENT NO:
DATE:
SUPERSEDES:
VGF*
Cylinder Heads
7-4156
September 2021
New
SUBJECT: Valve Adjustment
MODELS AFFECTED: VGF Engines
The purpose of this bulletin is to inform the field
of the proper method to position the crankshaft
for valve adjustment on VGF engines.
NOTICE
PREPARING ENGINE FOR VALVE
ADJUSTMENT
Shut the engine down and allow it to cool to
room temperature before adjusting the valves.
In any procedure where the rocker arms may have
been removed or disturbed, the cylinder head
replaced, or if it is suspected that the valves may
have been adjusted incorrectly, do not rotate the
crankshaft until all rocker arm adjusting screws and
valve bridge adjusting screws have been backed off.
Failure to back off the adjusting screws in these
situations may cause contact between valves and
pistons.
! WARNING
Allow the engine to cool to
room temperature before
servicing the engine. Some
engine components and fluids
are extremely hot even after the
engine has been shut down.
Allow sufficient time for all
engine components and fluids
to cool to room temperature
before attempting any service
procedure.
1.
Position cylinder No. 1 on the F18 and H24, or 1R
on the L36 and P48 at TDC of the
compression stroke. Rotate the crankshaft
by barring the engine over in a
counterclockwise direction (when facing the
flywheel) until the piston of cylinder No. 1 is at
TDC (compression stroke).
2. To determine when this piston is at top dead
center (compression stroke), watch the
rocker arms and valves on its mating
cylinder (see Figure 1). As the exhaust valves
on the mating cylinder are closing, the intake
valves begin to open. At this point, the
mating cylinder is in valve overlap (all four
valves partially open). This means that all
four valves on the cylinder to be adjusted are
fully closed.
* Trademark of INNIO Waukesha Gas Engines, Inc.
All other trademarks are the property of their respective owners.
09/02/2021
Copyright © 2021, INNIO Waukesha Gas Engines, Inc.
Page 1 of 3
Service Bulletin No. 7-4156
Table 1: H24SE, VGF H24 Crankshaft Positioning
1
2
7
3
3
2
4
7
5
6
Figure 1: Rocker Arm Adjustment
1 - Crossbar
Adjustment
5 - Rocker Arm
2 - Exhaust Valve
6 - Valve Clearance
Adjustment
3 - Measure Gap
With Feeler Gauge
7 - Intake Valve
4 - Crossbar
Both intake and exhaust valves are adjusted on
each cylinder when it is at TDC. Begin with
cylinder No. 1 or 1R and adjust valves on
subsequent cylinders in the firing order,
watching the mating cylinder go into valve
overlap to determine TDC on each cylinder to be
adjusted. Do this until all the cylinders have been
adjusted. After all valves are adjusted and
before starting the engine, use the engine
barring device to manually rotate the engine in
a counterclockwise direction, to be certain that
no oversights have occurred that might cause
valve and piston interference.
SET VALVES ON
CYLINDER
WHEN VALVES OVERLAP
ON
MATING CYLINDER
1
4
2
6
8
5
7
3
8
5
7
3
1
4
2
6
Table 2: F18SE, VGF F18 Crankshaft Positioning
SET VALVES ON
CYLINDER
WHEN VALVES OVERLAP
ON
MATING CYLINDER
1
5
3
6
2
4
6
2
4
1
5
3
Table 3: L36 Crankshaft Positioning
SET VALVES ON
CYLINDER
WHEN VALVES OVERLAP
ON
MATING CYLINDER
1R
6L
5R
2L
3R
4L
6R
1L
2R
5L
4R
3L
6R
1L
2R
5L
4R
3L
1R
6L
5R
2L
3R
4L
09/02/2021
Copyright © 2021, INNIO Waukesha Gas Engines, Inc.
Page 2 of 3
Service Bulletin No. 7-4156
Table 4: P48 Crankshaft Positioning
SET VALVES ON
CYLINDER
WHEN VALVES OVERLAP
ON
MATING CYLINDER
1R
1L
4R
4L
2R
2L
6R
6L
8R
8L
5R
5L
7R
7L
3R
3L
8R
8L
5R
5L
7R
7L
3R
3L
1R
1L
4R
4L
2R
2L
6R
6L
09/02/2021
Copyright © 2021, INNIO Waukesha Gas Engines, Inc.
Page 3 of 3
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