Kubota — Checking Engine Oil Pressure
Testing & diagnosis · Lubrication system
From a Kubota service manual covering: Hurth HBW 100, Hurth HBW 125, Hurth HBW 150, Hurth HBW 250, Hurth HBW 35, Hurth HBW 50, M-25XPB, M-35B, M-40B. Check it applies to your exact model before use.
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Before you start
- Do not use lock pliers, vise grips or pipe wrenches on the oil pressure switch; use the correct socket.
Procedure
- Remove the oil pressure switch and install a mechanical oil pressure gauge.
- Start the engine and warm to operating temperature.
- Measure oil pressure at both idling and rated speeds.
- If below the specified limit, check oil level, pump, strainer, filter and gallery.
- Also check bearing oil clearances and the relief valve for foreign matter.
- Reinstall the oil pressure switch and tighten to specified torque.
Tools required
- Mechanical oil pressure gauge Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Idle speed: 15 psi (103.4 kPa)
- Rated speed: 40 - 60 psi (276 - 414 kPa)
- Switch torque: 10.8 - 14.5 ft-lb (1.5 - 2.0 kg-m)
Source: Kubota 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.