Cummins/Onan 4.0BF-1R/9500 — Engine Disassembly

For the Cummins/Onan 4.0BF-1R/9500.

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Procedure

1. Drain crankcase oil.
2. Disconnect all exhaust lines, fuel lines and electrical wires (tag all electrical wires).
3. Remove engine from its slide rails and mountings and place on a suitable bench or work stand.
4. Remove all shrouds, mounts, air cleaner, control box, etc.
5. Remove flywheel, using a puller or pry-bar method.
6. Remove flywheel alternator stator.
7. Remove the gear cover, being careful to protect the oil seal from keyway damage.
8. Remove the crank gear, using a gear puller and ring.
9. Remove fuel pump, oil filter, starter, carburetor, fuel lines, spark plugs, etc.
10. Remove breaker box.
11. Remove oil base, oil pump and cylinder heads.
12. Remove valves, springs, lifters, etc.
13. Remove camshaft and gear assembly.
14. Remove connecting rods, pistons and bearings.
15. Remove rear bearing plate.
16. Remove crankshaft.
17. Remove front main bearing.

Source: manual:965-0515 Onan 4kwBF RV Genset Major Service manual (09-1973).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.