Kohler — Gear Pump Flow and System Relief Pressure Test
Testing & diagnosis · Hydraulic gear pump
From a Kohler service manual — check it applies to your exact model before use.
Applies to: Kohler LH775 engine
Before you start
- Failure to use gauge with recommended pressure rating could result in damage or injury.
Procedure
- Operate vehicle approximately 10 minutes to reach normal oil temperature.
- Park on level surface, raise/support bed, shut engine off, relieve system pressure.
- Disconnect pressure hose from gear pump; install tester with gauges and flow meter in series.
- Start engine and run at low idle; check for leaks.
- Fully depress accelerator pedal; verify engine speed is 3600 RPM.
- Slowly close flow control valve until 1500 PSI (103 bar); record flow.
- Good pump flow approximately 4.5 GPM (17.0 LPM) at 1500 PSI.
- If flow less than 3.8 GPM or 1500 PSI cannot be obtained, inspect pump suction line and pump.
- To test relief pressure, turn steering wheel to full lock momentarily; system pressure should be approximately 1800 PSI (124 bar).
- Remove tester and reinstall hose.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Flow approximately 4.5 GPM (17.0 LPM) at 1500 PSI
- System relief approximately 1800 PSI (124 bar)
Source: Kohler 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.