
Doc. No.: OMS500000104
Rev: A Page 26 of 42
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property of FMC Technologies, and may not be reproduced, disclosed, or made public in any manner prior to express written authorization by FMC.
9.4
Replacing Valves
1. Two types of valves may be supplied with an M28 pump. They are disc type valves and
AR style valves. The next steps must be performed for either type of valve.
2. Adequate clearance is required above, below, and in front of the pump fluid cylinder to
allow valve service without removal of the fluid end. If sufficient clearance is not
available, the fluid end must be removed as outlined in other sections and taken to a work
shop for valve service. The following procedure is written under the assumption that
sufficient clearance exists.
3. Loosen the hex nuts (64) that retain the three valve covers (51) on the top of the fluid
cylinder. Remove the covers (51).
4. For AR type valves refer to
. This document describes the methods for
removing and installing the AR valves.
5. For disc type valves refer to
. This document describes the methods for
removing and installing disc valves.
6. After the valves have been replaced, inspect the o-ring (52) on the valve cover (51).
FMC recommends that the valve cover o-rings (52) be replaced at this service interval
even if they do not appear damaged. Fit the valve cover (51) with the o-ring (52) in place
over the studs (58). Replace valve cover lock washers (69) and the valve cover hex nuts
(64). Torque the cover hex nuts (64) to the recommend values listed in the Fastener
Torque Requirements section of this manual.
9.5
Servicing the Power End
1. Disconnect the driver from the pump and insure that suction and discharge lines are
disconnected or blocked and have no pressure applied. Removal of the fluid cylinder
simplifies most power end service procedures.
2. Remove magnetic pipe plugs (28) from bottom of pump and allow all oil to drain from
crankcase.
3. Remove the 28 rear cover cap screws (20). Remove the back cover (10) and back cover
gasket (14) from the pump case (1).