Cummins/Onan 6.5NH - 3CR / 6000 A — Oil Seal Replacement (Gear Cover and Bearing Plate)
Repair & overhaul · Oil seals
For the Cummins/Onan 6.5NH - 3CR / 6000 A, from the Cummins/Onan service manual.
Applies to: Cummins/Onan NH engine
Procedure
- The bearing plate must be removed to replace its oil seal.
- Drive the oil seal out from the inside using bearing plate driver 420-0181 and gear cover driver 420-0313.
- Fill the space between seals with fibrous grease or stiff cup grease to improve sealing.
- Install the gear cover oil seal by tapping inward until 31/32 inch from the mounting face; new style thin open face seal 1-7/64 inches from the mounting face.
- Install the bearing plate oil seal to bottom against the shoulder in the plate bore.
- Use a seal expander or shim stock around the crankshaft end when replacing the bearing plate to avoid damaging the seal.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Gear cover seal 31/32 inch from mounting face
- New style seal 1-7/64 inches from mounting face
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.