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TM 10-3930-671-24
10.3. Main Hydraulic Pump
Removal/Installation
Pump Specifications ........................................................................................................................... F-457
Pump Troubleshooting ....................................................................................................................... F-457
Main Pump Mounting Installation ....................................................................................................... F-458
Pump Removal ................................................................................................................................... F-458
Pump Installation ................................................................................................................................ F-458
Pump Specifications
The main hydraulic (lift) pump is a fixed-displacement,
high-performance, pressure-compensated gear pump.
The pump is mounted to a drive pad on the transmission
driven either by a gear train or silent chain drive from the
torque converter impeller.
Model
Displacement
Speed
Pressure Flow
cu in/rev
rpm
psi
gpm
S205-12 1.45
1800
3000
9.6
Rotation viewing drive end:
............... Clockwise
Inlet port: ............................................... 1-1/16-12 UN
Outlet port: ............................................ 7/8-14 UN
Pump Troubleshooting
If a hydraulic system or pump problem is evident, before
removing and/or disassembling the lift pump, check the
following list of problems and solutions. It could save
time, work and cost.
1.
Noisy Pump
1)
Low oil level
Check/fill sump
2)
011 too heavy
Change to correct viscosity
3)
Inlet line restriction
Check for foreign material,
clean filter or strainer
4)
Air leak In inlet line Check plumbing tightness
2.
Low Pump Output (Low Flow)
1)
Cavitating pump
See 1. Noisy Pump above
2)
Air in fluid
Wrong fluid-Drain/refill
w/correct oil
3)
System relief valve
Correct relief valve,
set too low/high, stuck
pump may be OK
or leaking
4)
Overheated oil
Correct oil temperature problem
5)
Contaminated fluid
Correct,
inspect
&
rebuild
6)
Pressure loading Replace, rebuild
seal collapsed
7)
Gear face, body or
Repair, rebuild
cover nicks
8)
Excessive side loading, wear
Inspect & rebuild
plate tight in body bore,
pinched thrust plate
3.
Foaming Oil
1)
Cavitating pump
See 1. Noisy Pump above
2)
Wrong fluid
Drain and refill w/correct oil
4.
Heated Pump and/or Oil
1)
Thin oil
Drain/fill with correct oil
2)
Contaminated oil
Drain/clean filter/fill
3)
Cavitating pump.
See 1. Noisy Pump above
4)
Drive shaft misaligned
Check mounting & alignment
5)
Axial loading on drive
Check shaft end clearance
shaft and shaft alignment
Check for worn key/spline
6)
Relief valve usually in
Check relief setting
bypass
5.
Shaft Seal Leakage
1)
Damaged or worn seal
Replace
2)
Shaft scratched or worn
Repair (polish or replace)
2)
Front cover bearing out
Replace front cover
of position
assembly
3)
Shaft seal housing bore
Same as 2
scratched
4)
Improper fit of shaft
Same as 2
5)
Contamination
Inspect & rebuild
6)
Pump run w/wrong rotation
Replace shaft &
pressure loading seals
7)
Shaft scratched or seal
Repair (polish shaft) or
nicked
replace shaft seal
and gear
8)
Seal installed backwards
Inspect & rebuild
6.
External Leakage
1)
Faulty seal gasket
Replace
2)
Damaged surfaces
Correct & replace as req’d
on body or cover
3)
Distorted seal gasket
Correct & replace as req’d
4)
Excessive system
Correct as req’d
pressure
7.
Failure to Build Pressure
1)
Defective relief valve
Repair and reset valve
2)
Low oil supply
Fill sump
F-457
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