Yanmar 4BY, Service Manual, Page: 107 / 275

ENGINE
5-52
BY Service Manual
Camshaft and Timing Gear Train
Removing Timing Case Cover
IMPORTANT
When working on the oil, coolant or fuel
circuits you must protect the alternator from
contamination. Cover alternator with
suitable materials. Failure to comply may
result in an alternator failure.
1. Disconnect battery negative (-) cable.
2. Drain engine coolant. See Draining and Filling
Closed Cooling System on page 7-12.
3. Remove alternator and seawater pump drive
belts. See Remove and Install Alternator on
page 11-7 and Replace Seawater Pump Belt on
page 7-21.
4. Remove oil sump. See Remove and Install Oil
Sump on page 8-16.
5. Remove cylinder head. See Removal of
Cylinder Head on page 5-23.
6. Remove vibration dampener. See Removing
and Installing Vibration Damper - 4BY on
page 5-50 or Removing and Installing Vibration
Damper - 6BY on page 5-51.
7. Remove front crankshaft seal. See Replacing
Front Crankshaft Seal on page 5-68.
8. Remove alternator belt tensioner.
9. 4BY: Remove alternator. See Remove and
Install Alternator on page 11-7.
Figure 5-82
10. Remove bolts securing cover and remove
timing case cover (Figure 5-82) .
Figure 5-83
11. If the coolant pump has not been removed, cut
the gasket at the three tabs (Figure 5-83, (1)) .
and remove timing case cover portion of
gasket.
Removing and Installing Timing
Chain
1. Remove timing case cover. See Removing
Timing Case Cover on page 5-52 .
Figure 5-84
2. Compress chain tensioner rail
(Figure 5-84, (3)) and retain with special tool
OEM No. 11 3 340 (Figure 5-84, (1)) .
3. Remove tensioner rail (Figure 5-84, (3)) and
guide rail (Figure 5-84, (4)) .
4. Remove nut (Figure 5-84, (2)) .