Checking Engine Oil Pressure; Trochoid Oil Pump; Oil Pump Components - Yanmar 4TNV98 Service Manual

Checking Engine Oil Pressure

Perform an engine oil pressure check if there is any
indication of low oil pressure such as the oil
pressure indicator is on or the oil pressure gauge
indicates low oil pressure. See Engine Oil Pressure -
All Models on page 212.
1. Disconnect the wire lead from the oil pressure
switch or sending unit (Figure 9-2, (1)).
Figure 9-2
2. Remove the oil pressure switch.
3. Install a mechanical oil pressure gauge in the oil
pressure switch port.
4. Start the engine:
• If the mechanical oil pressure test gauge
indicates good oil pressure, replace the faulty
oil pressure switch or sending unit, or faulty
machine oil pressure gauge in instrument panel.
• If the mechanical oil pressure test gauge
indicates low oil pressure, troubleshoot the
lubrication system to locate the cause of the low
oil pressure. See Troubleshooting Charts on
page 190. Repair as necessary.
4TNV98 & 4TNE98 Diesel Engine

Trochoid Oil Pump

Oil Pump Components

The oil pump on these model engines is located in
the front gear case and is driven by the same gear
train that drives the camshaft and fuel injection
pump. You must remove the front gear case cover to
gain access to the oil pump.
(1) Gear Case Housing.
(2) Outer Rotor.
(3) Inner Rotor.
(4) Cover Plate.
(5) Drive Gear.
215
Figure 9-14
Section 6. Lubrication System