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Normally, the valves should not be interfered with until they are no longer completely tight. Usually,
this can be heard in the exhaust when the engine is idling, or when starting difficulties appear. Turn
the pistons against top with closed compression cocks. If the valves can be heard blowing in the
exhaust or suction channels, they need grinding. To grind the valves, it will be necessary to remove
the cylinder covers. See also sheet 7-6.
The valve clearance which can be adjusted by means of an adjusting screw in the rocking lever must
be 0.60 mm for the exhaust valve as well as for the suction valve. The same value applies to cold
and warm engine.
Main bearing clearance is between 0.10 mm and 0.12 mm, crank bearing clearance 0.15 mm. The
space between piston and cylinder cover is 2.20 - 2.40 mm. The copper packing between cylinder
and cover is 1.00 mm. The indicated space between piston and cylinder cover equals a compression
pressure of about 38 kp/cm². At this pressure the engine is certain to start even at low temperatures.
The engine has to work on an firing pressure of about 65 kp/cm². To obtain this pressure the fuel
must be injected as follows: When the mark in the pump lever in the oval hole at the bottom of the
fuel pump is in middle position, the top marking on the flywheel must be 48 mm before top measured
on the circumference of the flywheel for turbocharged engines, and 78 mm before top for engines
without turbocharger. This method is only a rough checking; for fine adjustment a drip pipe should be
used - see sheet 7-45.
The adjustment of the valves should be as follows: Suction opens 524/270 mm before top, exhaust
closes 524/150 mm after top, measured on the circumference of the flywheel, for engines with
turbocharger and without turbocharger, respectively. All indicated valve and fuel pump adjustments
apply to a flywheel diameter of 1000 mm.
The freshwater and oil cooler must be cleaned in the saltwater circuit at suitable intervals (when
necessary). For this purpose remove the end covers and clean the cooler pipe by means of a brush.
Rinse the cooler. Check the anodes and, if necessary, replace them on same occasion.
If the alarm device supervising the cooling water temperature is giving a signal, the cause may be
that the thermostat is broken (if so, the thermostat can be removed; it is placed in the front flange on
top of the cooler) or that the cooler has to be cleaned. It may also be due to insufficient water in the
cooling system, because of a leaking water or oil cooler.
If the water has been drained off for repair of the engine, it may be impossible to replenish enough
water, usually because the expansion tank piping has clogged, for which reason the pipes must be
cleaned. Should the oil cooler leak, it will be indicated by rising oil level because water is running out
into the lubricating oil; this will only happen when the engine is not running. When the engine is
running and there is pressure on the lubricating oil, the oil may possibly be seen in the cooling water
outboard.
If there is a leakage in the freshwater circuit of the cooler, it is indicated by too little freshwater which,
however, cannot normally be seen until the engine has been stopped; when the engine is running
there is pressure in the cooler, for which reason the volume of freshwater does not decrease. Should
the latter happen, the cooling water system will only have to be replenished, preferably with
freshwater, but otherwise with seawater. Then you can run the engine safely until arriving in harbour
where the cooler can be repaired.
The coarse filter (water trap) must be emptied of water and mud about once a week by opening the
lower cock until pure fuel oil is running out.
7-94-2A
Callesen Diesel
Page 8 of 12
Sheet No.
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