Cummins/Onan — Cooling System Disassembly
Repair & overhaul
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Overheating might result in engine damage. Never operate with cooling system components removed.
Procedure
- Remove heat shields, exhaust downpipe, and exhaust manifold.
- Remove rubber air seal from around oil filter.
- Loosen 1/4 inch hex head cap screws securing left and right air housings; remove air housings.
- Loosen 1/4 inch hex head cap screws securing scroll to backplate; remove scroll.
- Loosen flywheel capscrew and remove flywheel washer. Replace capscrew and tighten finger tight.
- Attach puller tool to flywheel; tighten puller center screw until flywheel is loose; remove flywheel.
- Remove lead from low oil pressure cut-off switch.
- Loosen 1/4 inch hex head cap screws securing backplate to engine; remove backplate.
- Use brush or low pressure compressed air to remove dirt or debris from engine cooling fins.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.