Yanmar 3TNV Series Service Manual page 73

(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
Air cleaner element
1
Valve clearance
2
valve timing
3
Cylinder head gasket
4
Intake/exhaust vale
Valve seat
5
Piston
6 Piston ring
Cylinder
Cause
Clogged element
Broken element
Defect at element seal
portion
Excessive or no
clearance
Incorrect valve clearance
Gas leak from gasket
Gas leak due to worn
valve seat or foreign
matter trapping
Sticking valve
Gas leak due to
scratching or wear
58
Corrective action
Clean the element.
Replace the element.
Adjust the valve clearance.
(See 3.5 in Chapter 3.)
Adjust the valve clearance.
(See 3.5 in Chapter 3.)
Replace the gasket.
Retighten the cylinder head bolts to the
specified torque.
(See 4.2(2)12) in Chapter 4.)
Lap the valve seat.
(See 4.2(6) in Chapter 4.)
Replace the intake/exhaust valve.
Perform honing and use an oversized part.
(See 4.4(5)-(5-1), (5-4) and (6) in Chapter 4.)
3. Troubleshooting