B5.9G, B5.9LPG, B Gas Plus, B LPG Plus, and B Gas International Engines – 003-004   Overhead Set

Diagnosing Component Malfunctions – Rocker Lever, Valve Stem, Push Tube, Tappet, and Camshaft

The rocker lever group consists of the rocker lever assemblies, rocker assembly oil manifold, valve cover, and crankcase breather.

Each cylinder of the engine has a separate rocker lever assembly. The pedestal support has drillings to route the oil flow to the shaft and levers.

The rocker levers are push tube actuated and use an adjusting screw to control the clearance between the rocker lever and valve stem. The rocker levers do
not use a bushing in the bore for the rocker lever shaft. The rocker lever
must be replaced if the bore is damaged or worn beyond the specification limit.

The ball end of the push tube fits into the ball socket in the tappet. The other end of the push rod has a ball socket in which the ball end of the rocker lever adjusting screw operates.

NOTE: The phosphorous and zinc levels in midrange natural gas engine oils help in the lubricating of sliding tappets.

Excessive valve lash can indicate a worn valve stem, push tube, valve tappet, or rocker lever.

NOTE: All valve adjustments
must be made when the engine is cold, and stabilized coolant temperatures are at 60°C [140°F] or below.

Remove the rocker lever cover capscrews, insulators, and spacers from the cover.

Remove the rocker lever covers.

The crankshaft rotation is
clockwise when viewed from the front of the engine.

The cylinders are numbered from the front gear housing end of the engine.

The firing order is 1-5-3-6-2-4.

Each cylinder has two rocker levers:

• The rocker lever “E” is the exhaust lever.
• The rocker lever “I” is the intake lever.

Use the accompanying illustration for valve rocker lever locations.

Engine Barring Tool, Part Number 3824591

Locate top dead center for cylinder number 1 by barring the crankshaft slowly. Barring the engine from the flywheel on the rear of the engine is recommended.

Feeler Gauge

NOTE: The clearance is correct when some resistance is “felt” when the feeler gauge is slipped between the valve stem and the rocker lever.

Engine Valve Adjustment

Locate top dead center for cylinder number 1.

Set
only the valves indicated by the arrows in the illustration (E = exhaust, I = intake).

Holding the locknut steady with the wrench, adjust the valve clearance with the screwdriver or Allen wrench.

Tighten the locknut and measure the valve lash again.

Mark the pulley, and rotate the crankshaft 360 degrees.

Adjust the valves as indicated in the illustration.

Set
only the valves indicated by the arrows in the illustration (E = exhaust, I = intake). Do
not set valves that are
not indicated.

Install the rocker lever covers, and tighten the capscrews.