YANMAR Diesel Engine 1GM, 2GM, 3GMD, 3HM. Manual - part 12

Important

If the canister is overtightened,
difficulty may be experienced in
its removal and the filter may be
damaged.

2. New Lub. Oil

1-c)-6. Start engine and check for leaks. Check oil level after
running the engine for several minutes and fill up when
necessary.

2) Reduction/reversing gear case oil.

2-a) Check the oil level before every operation.

3. New Cannister

2-b) Replace the oil. Replace the oil periodically same
procedure as engine lube oil.

Important
Reduction/reversing gear case oil for 3GMD and 3HM
is different from engine lube oil.

[9-3.] Cooling water system

1) Make sure that water is coming out of the cooling water
outlet pipe during operation.

2) Inspection and replacement of anticorrosion zinc.
Replace the anticorrosion zinc after every 500 hours of use
to prevent electrolytic corrosion by the cooling water.
Although it depends on the quality of the raw water and the
operating conditions, remove the scum(dross) adhering to
the surface of the anticorrosion zinc.
If less than 1/2 of the anticorrosion zinc is left, it should be
replaced with a new one.

Location of anticorrosion zinc

Number of Pieces

1GM

2GM

3GMD

3HM

Cylinder Head

 –

  1

    1

   1

Cylinder Body

   1

  1

    2

   2

3) Inspection and replacement of cooling water pump.

3-a) Impeller of the cooling water pump.

3-a)-1.
Remove the cooling water pump cover, take out the
impeller, and check for damage to the impeller and
mechanical seal parts. If damaged, replace with a new
one.
1. Cover

2. Packing
3. Impeller
4. Cooling Water Pump

3-a)-2.
When reassembling the pump, coat the fittings of the pump shaft and impeller, both sides of
the impeller, and the vane tips with grease.

Important
When installing the impeller, make sure the direction of the impeller cor-
responds to that indicated in the figure.

3-b)
Adjust the V-belt tension. Check the tension of the
cooling water pump drive belt. If there is too much
tension premature damage to the V-belt will occur. On
the other hand of the V-belt pulley is loose it will slip
and cooling water flow will be insufficient. Loosen the
cooling water pump V-belt tension bolt to adjust the
tension.
Replace the belt if it is worn or cracked.

Adjustment Standard – 5 - 7 mm (with 10 kg
thumb force)

[9-4.] Inspection of engine body

1) Retightening cylinder head nuts Retighten each nut with a torque wrench before starting a
new engine and after 50 hours of operation. Sequence for tightening the nuts is shown in the
figure.

1. For 1GM M10 bolts are used for main
2. Sub
3. Number shows tightening order

CYLINDER HEAD TIGHTENING TORQUE

1GM

MAIN (M10)

7.5 kg-m

2GM, 3GMD MAIN (M12)

10 kg-m

SUB (M8)

2.5 kg-m

3HM

MAIN (M12)

13 kg-m

SUB (M8)

3 kg-m

2) Exhaust/intake valve head clearance adjustment
The clearance of the valve will affect the overall performance
of the engine, so it is important that it be correctly adjusted.
Check the clearance before starting a new engine, whenever
assembling or disassembling and after 500 hours of
operation. Adjustment shall be done while the engine is cold.

2-a)
Remove the valve rocker arm cover and starter motor.