SERVICING THE PLUNGERS
1851/1851K AND 1861/1861K
Disassembly
NOTE: Both the standard and the “K” versions are serviced
in the same manner.
1. To service the plungers, it is necessary to remove the
Discharge Manifold, the VBM and Inlet Manifold. Follow the
disassembly procedure found under SERVICING THE
VALVES, steps 2 and 3.
2. Remove the one-piece Seal Retainer from each Plunger Rod.
3. Using a Hex tool, loosen the Plunger Retainers about three to
four turns.
4. Push the Ceramic Plungers back towards the crankcase to
separate from the Plunger Retainers and proceed with un-
threading the Plunger Retainers by hand.
5. Remove Plunger Retainers, O-Rings, Back-up-Rings and
Gaskets.
NOTE: Plunger Retainer Studs may stay on Plunger
Rods or come off with Plunger Retainers.
6. Remove Ceramic Plungers, Collar Spacers, Keyhole
Washers and Barrier Slingers.
Reassembly
1. Visually inspect Crankcase Oil Seals for deterioration or leaks
and contact CAT PUMPS for assistance with replacement.
2. Examine Plunger Retainer Studs, Barrier Slingers, Keyhole
Washers and Collar Spacers for wear and replace as needed.
3. Slide Barrier Slingers over Plunger Retainer Studs with con-
cave side away from crankcase.
4. Slide Keyhole Washers over Plunger Retainer Studs with
split ends facing downward.
5. Slide Collar Spacer over Plunger Retainer Studs.
6. Examine Ceramic Plungers for scoring, scale build-up, chips
or cracks and replace as needed.
7. Slide Ceramic Plungers over Plunger Retainer Studs.
NOTE: Plunger can only be installed in one direction. Do
not force onto Plunger Rod.
8. Examine Gaskets, O-Rings and Back-up-Rings for cuts or
wear and replace as needed.
9. Examine Plunger Retainers for wear or damaged threads and
replace as needed.
Plunger arrangement
10. Install Gaskets first, then O-Rings and Back-up-Rings onto
Plunger Retainers.
NOTE: Lubricate O-Rings and Back-up-Rings for ease in
installation and to reduce possible damage.
11. Apply Loctite 242 to exposed threaded end of Plunger
Retainer Studs, thread on Plunger Retainer and torque per
chart.
12. Install Seal Retainers with drain slots facing to the top and
bottom.
NOTE: Wicks are not used on these models.
13. Support the Inlet Manifold from the under side and slide man-
ifold over Manifold Studs.
14. Support the VBM from the under side and slide manifold over
Manifold Studs. Apply anti-seize to HSH screw threads and
thread in hand tight. Torque in sequence to specifications in
torque chart.
15. Support the Discharge Manifold from the under side and slide
over Manifold Studs. Install Flat Washers and LockWashers.
Apply anti-seize to manifold studs and nuts, and thread nut in
hand tight. Torque in sequence to specifications in torque
chart.
SERVICING THE CRANKCASE SECTION
1851/1851K AND 1861/1861K
NOTE: Both the standard and the “K” versions are serviced
in the same manner.
1. While manifolds, plungers and seal retainers are
removed examine crankcase oil seals for leaking and wear.
2. Check for any signs of leaking at Rear Cover, Drain Plug and
Bubble Gauge.
3. Check oil level and check for evidence of water in oil.
4. Rotate crankshaft by hand to feel for smooth bearing movement.
5. Examine crankshaft oil seals externally for drying, cracking or
leaking.
6. Consult CAT PUMPS or your local distributor if crankcase
service is required. See also Tech Bulletin 035.
