1.7.1 Gear Train and Timing
DETROIT DIESEL 53
Lubrication
The gear train is lubricated by the overflow of oil from the camshaft and balance shaft pockets spilling into the
gear train compartment. A certain amount of the oil also spills into the gear train compartment from the
camshaft and balance shaft end bearings and the idler gear bearing.
ENGINE TIMING
The correct relationship between the crankshaft and camshaft(s) must be maintained to properly control fuel
injection and the opening and closing of the exhaust valves.
The crankshaft timing gear can be mounted in only one position since it is keyed to the crankshaft. The
camshaft gear(s) can also be mounted in only one position due to the location of the keyway relative to the
cams. Therefore, when the engine is properly timed, the markings on the various gears will match as shown in
Fig . 1.
Pre-ignition. uneven running and a loss of power may result if an engine is "out of time".
When an engine is suspected of being out of time, due to an improperly assembled gear train, a quick check
can be made without removing the flywheel and flywheel housing by following the procedure outlined below.
Check Engine Timing
Access to the crankshaft pulley, to mark the top dead center position of the selected piston, and to the front end
of the crankshaft or the flywheel for turning the crankshaft is necessary when performing the timing check.
Then, proceed as follows:
1. Clean and remove the valve rocker cover.
2. Select any cylinder for the timing check.
3. Remove the injector as outlined in Section 2.1 or 2.1.1.
4. Carefully slide a rod, approximately 12" long, through the injector tube until the end of the rod rests on top
of the piston. Place the throttle in the no-fuel position. Then, turn the crankshaft slowly in the direction of
engine rotation. Stop when the rod reaches the end of its upward travel. Remove the rod and turn the
crankshaft, opposite the direction of rotation, between 1/16 and 1/8 of a turn.
5. Select a dial indicator with .001" graduations and a spindle movement of at least 1". Provide an extension
for the indicator spindle. The extension must be long enough to contact the piston just before it reaches the
end of its upward stroke. Also, select suitable mounting attachments for the indicator so it can be mounted
over the injector tube in the cylinder head.
6. Mount the indicator over the injector tube. Check to be sure the indicator spindle extension is free in the
injector tube and is free to travel at least one inch.
7. Attach a suitable pointer to the engine lower front cover. The outer end of the pointer should extend out
over the top of the crankshaft pulley.
8. Turn the crankshaft slowly, in the direction of engine rotation, until the indicator hand just stops moving.
9. Continue to turn the crankshaft, in the direction of rotation, until the indicator starts to move again. Now set
the indicator on zero and continue to turn the crankshaft until the indicator reading is .010".
*INDICATOR
READING
Engine
Standard
Retarded
Advanced
1-Tooth
1-Tooth
STANDARD
TIMING
.228"
.204"
.245"
(1) 3
.206"
.179"
.232"
(2) 3 -
ADVANCED
TIMING
(2) 3
.232"
206"
.258"
* Indicator readingsshown are nominal values. The allowable tolerance is + .005 in.
(1) High velocity type injector cam.
(2) Low velocity type injector cam.
TABLE 1
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