Testing Compression Pressure - Komatsu PC88MR-10 Shop Manual

30 Testing and adjusting
Engine and cooling system

Testing compression pressure

a Testing tools
Sym-
Part No.
bol
795-502-1590 Compression gauge
1
795-502-1800 Adapter
2
3 6275-11-3880 Gasket
D
6275-11-3890 O-ring
4
Commercially
5
available
Place the machine on a level ground and
lower the work equipment to the ground.
Turn the battery connect switch to OFF
position, and remove the key.
When testing the compression pressure, be
careful not to burn yourself by touching the
exhaust manifold or KDPF, or get caught in a
rotating part.
a Check this item under the following conditions.
Engine oil temperature: 40 to 60°C
Testing
(PC88MR-A000-36B-K-00-A)
1. Remove cylinder head cover, injector connector,
and high-pressure pipes. For details, see
Disassembly and assembly, "Removal and
installation of injector assembly".
2. Set the cylinders to check to the compression
top dead center. For details, see "Testing and
adjusting valve clearance".
a Confirm the compression top dead center of
the cylinder by checking that you can move
both of the intake rocker arm exhaust rocker
arm by the distance equivalent to the valve
clearance.
3. Drain the fuel and its level lowers to 1/4 (about
31l: F5 of the fuel level gauge).
a It is because it may flow back from the return
circuit when the engine is cranked.
30-12
(PC88MR-A000-360-K-01-A)
Part name
Hose/inside diameter:
approximately 15 mm
4. Loosen injector terminal nuts (16), and remove
the terminals from injector (15).
a Insulate the terminals with tape etc. so that
they do not touch each other.
Remove the holder to remove injector (15).
5. Install gasket D3 to the tip of adapter D2 and
insert them into the mounting part of injector
(15).
6. Fix adapter D2 with mounting holders (17) for
the injector.
Mounting bolt:
39 to 49 Nm {4.0 to 5.0 kgm}
a Tighten the mounting bolt while the fulcrum of
the holder is seated perfectly.
a Do not reuse the holder mounting bolt.
7. Connect compression gauge D1 to adapter D2.
PC88MR-10