GHAB — CYLINDER COMPRESSION TEST

For the GHAB.

Procedure

1. Start the genset and let it warm up.
2. Stop the genset and remove and inspect the spark plugs. See Ignition System in this sec- tion.
3. Insert the compression gauge nozzle into one of the spark plug holes, hold the throttle open and crank the engine. Note the pressure indi- cated by the gauge.
4. Repeat the test on the other cylinder.
5. See Engine Block Assembly in Section 7 if cyl- inder compression test pressures do not meet Specifications. Redistribution or publication of this document, by any means, is strictly prohibited. VALVE CLEARANCE (LASH) ADJUSTMENT See Figure 6-1. The engine is equipped with adjust- able valve tappets. Adjust the valve clearance only when the engine is at ambient temperature:
6. Remove the roof panel. See Removing And Installing The Housing Panels in Section 5.
7. Remove the intake manifold to access the valve tappets. See Fuel System in this section. When performing this procedure, it is not nec- essary to remove the air cleaner housing (Fig- ure 6-11) from the carburetor or the carburetor from the intake manifold.
8. Remove the air intake screen from the engine divider panel (see Figure 5-1). To remove the four panel clips (screws) from air intake screen, turn out screw several turns and pull out panel clip. (Peel back foam insulation near air intake screen to expose panel clip screws.)
9. Remove the valve covers (use 7/16 inch sock- et).
10. Remove the spark plugs to make turning the engine easier (use 5/8 inch socket).
11. Place a 5/8 inch socket wrench on the flywheel capscrew and rotate the crankshaft in a clock- wise direction. While rotating the crankshaft, observe the valve/tappet movement of both cylinders. When either valve/tappet of one cyl- inder begins to move, the opposite cylinder valve/tappets can be adjusted. Repeat for op- posite cylinder.
12. When taking the clearance measurement, the feeler gauge should just pass between the valve stem and valve tappet. • Intake Valve Clearance (Cold)
13. To correct the valve clearance, use a 9/16 inch

Source: manual:965-0503B_Onan_GHAB_spec_A_Genset_Engine_Generator__Controls_Service_manual_11-1999.pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.