Allmand — Check Valve Load Drift Repair (Loose Parts)
Repair & overhaul
From a Allmand service manual covering: M-250 Series, M-258, M-259, M-301, M-303, M-304, M-310, M-311, M-313, M-314, M-319, M-326…. Check it applies to your exact model before use.
Before you start
- Divert oil into a container. Do not look into the port.
Procedure
- Remove the spring retainer.
- Measure depth of retainer so it can be reassembled to same depth.
- Remove spring.
- Remove ball or follower and ball.
- Start pump to flush dirt from seat area (divert oil into container; do not look into port).
- Inspect ball for damage and replace if necessary.
- Reinstall ball or ball and follower.
- Seat the ball using a small drift punch and hammer with a light tap.
- Reinstall the spring.
- Replace the spring retainer to the correct depth.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: Allmand 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.