DETROIT DIESEL 53
1.7.5
CRANKSHAFT TIMING GEAR
IN-LINE
ENGINE
The crankshaft timing gear is keyed and pressed on the crankshaft and drives the camshaft gear (In-line
engines) or balance shaft gear (In-line engines) through an idler gear.
Since the camshaft must be in time with the crankshaft, timing marks are located on the rim of the idler gear
with corresponding timing marks stamped on the crankshaft gear and camshaft and balance shaft gears (refer
Remove Crankshaft Timing Gear (Flywheel Housing Removed)
The crankshaft timing gear is a .001 " to .003 " press fit on the crankshaft. Remove the gear as follows:
1. Remove the crankshaft rear oil seal sleeve, if used. To remove the sleeve, peen the outside diameter of
the sleeve until it stretches sufficiently so it can be slipped off of the crankshaft.
2. Before removing the crankshaft gear, align the timing marks of the gear train and note their location so the
gear can be reinstalled in its original position.
3. Attach bar type puller J 4871 to the crankshaft gear with three long bolts or hooks, flat washers and nuts
through the holes in the gear as shown in Fig. 1.
4. Turn the center screw of the puller to pull the crankshaft gear off of the crankshaft. Inspection
Figure 1. Removing Crankshaft Timing Gear
Clean the gear with fuel oil and dry it with compressed air. Examine the gear teeth for evidence of scoring,
pitting or wear. If severely damaged or worn, install a new gear. Also check the other gears in the gear train.
Install Crankshaft Timing Gear
1. If removed, install the Woodruff key in the keyway in the crankshaft.
2. Start the timing gear over the end of the crankshaft with the timing marks on the outer rim of the gear
facing out and the keyway in the gear in alignment with the Woodruff key in the crankshaft.
3. Align the proper timing mark on the crankshaft gear with the corresponding mark on the idler gear (refer to
NOTE: When advanced timing is required, align the timing mark "A" with
the timing mark on the idler gear.
4. Place a heavy hammer against the head of the bolt in the front end of the crankshaft. Place installer J
7557 against the rear face of the timing gear and
Figure 2. Installing Crankshaft Timing Gear
March, 1973 SEC. 1.7.5 Page 1
