Yanmar 3JH4E, Service Manual

Page: 141 / 350

3. Troubleshooting
121
(3) Engine speed and compression pressure (for reference)
(4) Measured value and troubleshooting
When the measured compression pressure is below the limit value, inspect each part by referring to
the table below.
No. Item Cause Corrective action
1 • Air cleaner element • Clogged element
• Broken element
• Defect at element seal
portion
• Clean the element.
• Replace the element.
2 • Valve clearance • Excessive or no clearance • Adjust the valve clearance.
(See 2.2.6(7) in Chapter 2.)
3 • Valve timing • Incorrect valve clearance • Adjust the valve clearance.
(See 2.2.6(7) in Chapter 2.)
4 • Cylinder head
gasket
• Gas leak from gasket • Replace the gasket.
• Retighten the cylinder head bolts to the
specified torque.
(See 14.1 in Chapter 14.)
5 • Intake/exhaust vale
• Valve seat • Gas leak due to worn valve
seat or foreign matter
trapping
• Sticking valve
• Lap the valve seat.
(See 5.2.2 in Chapter 5.)
• Replace the intake/exhaust valve.
6 • Piston
• Piston ring
• Cylinder • Gas leak due to scratching
or wear
• Perform honing and use an oversized
part.
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
150 200 250 300 350 400 450
Engine speed (min
-1
)
Compression (MPa)
4HJ4-HTE
3JH4E/4JH4E/4JH4-TE
015522-00X