Giant P423, P425, P420-0011, P422, P420-0021 installation instructions

Repair Instructions P420/P420-0011/P420-0021/P422/P423 and P425

Note: Always take time to lubricate all metal and nonmetal parts with a light film of oil before reassembly. This step will ensure proper fit, at the same time protecting the pump nonmetal parts (i.e., the elastomers) from cutting and scoring.

1)With a socket wrench, remove the three discharge valve plugs and three inlet valve plugs (32). Inspect the o-ring (33) for wear and replace if damaged.

4)Remove the o-ring (31). Inspect all parts for wear and replace as necessary. Apply one drop of loctite 243 to the valve plugs (32) and tighten to 107 ft.-lbs. (145 NM).

7)Remove the pressure rings (24) and v-sleeves (23 - Note: P422 & P423 pumps have a support ring) from the valve casing (26).

2)Using needle nose pliers, remove the inlet and dis- charge valve assemblies (27A). Note: It may become neccesary to remove the valve seat (27) from the valve casing using a slidehammer.

5)Use a 8mm allen wrench to remove the 8 socket head cap screws (34). Carefully slide the valve casing (26) out over the plungers.

8)Remove the weep grooved seal (23 or 23B) together with pressure ring (24 _ P420 and P425 only) out of the seal adaptor (20). Check O-rings (21).

3)By inserting a small screw driver between the valve seat (27) and the valve spring re- tainer (30), the valve assem- bly can be separated.

6)Remove seal adaptors (20) and weep return rings (25) from the valve casing.

IMPORTANT! The grooved seal (23) on the high-pressure side is to be fitted carefully into the valve casing (26) using a screwdriver. Under no circumstances must the seal surface in the valve casing or the seal lip be damaged.

9