Engine Speed And Compression Pressure; Measured Value And Troubleshooting - Komatsu 4D98 Series Shop Manual

2.
Troubleshooting
(3) Engine speed and compression pressure (reference)
(kgf/cm*)
(MW
200
250 300
Engine speed (rpm)
350 400
(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
l
Air cleaner ele-
l
Clogged element
l
Clean the element.
ment
9 Broken element
l
Replace the element.
l
Defect at element seal
portion
2
l
Valve clearance
l
Excessive or no clearance
l
Adjust the valve clearance.
(See 3.5 in Chapter 3.)
3
l
Valve timing
l
Incorrect valve clearance
l
Adjust the valve clearance.
(See 3.5 in Chapter 3.)
4
l
Cylinder head
l
Gas leak from gasket
l
Replace the gasket.
gasket
l
Retighten the cylinder head
bolts to the specified torque.
(See 4.2 (2) @ in Chapter 4.)
5
l
Intake/exhaust
l
Gas leak due to worn valve
l
Lap the valve seat.
vale
seat or foreign matter
(See 4.2 (6) in Chapter 4.)
l
Valve seat
trapping
l
Replace the intake/exhaust
l
Sticking valve
valve.
6
l
Piston
9 Gas leak due to scratching
l
Perform honing and use an
l
Piston ring
or wear
oversized part.
l
Cylinder
(See 4.4 (5)-(5-1),(5-4) and
(6) in Chapter 4.)
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