4.236 & T4.236 DIESEL ENGINES Section P: Flywheel and Flywheel Housing Caterpillar

Section P: Flywheel and Flywheel Housing
1.1. To Remove the Flywheel
2.1. To Renew the Flywheel Ring Gear
3.1. To Refit the Flywheel
4.1. To Remove the Flywheel Housing
5.1. To Refit the Flywheel Housing
6.1. Oil Seal for Fluid Drive

To Remove the Flywheel

1. Remove the gearbox and flywheel housing.

2. Remove clutch assembly.

3. Remove the flywheel (see Note). With some applications, the flywheel is secured to the crankshaft with 12 setscrews and washers.

4. Remove the clutch pilot bearing (if fitted).

NOTE: To facilitate safe flywheel removal, remove two diametrically opposed securing setscrews and in their place, fit two suitably sized studs, finger tight only. The remaining setscrews can now be removed and the flywheel withdrawn under control.

To Renew the Flywheel Ring Gear

1. Place the flywheel in a suitable container of clean cold water and support it by positioning four metal blocks under the ring gear. Arrange the flywheel assembly so that, when placed in the water the ring gear is uppermost and clear of the water line by approximately 1/4 in (6,5 mm).

Heat the ring gear evenly around its circumference, thus expanding it. This will allow the flywheel to drop away from the ring gear.

2. Heat the new ring gear to an approximate temperature of 475°F (246°C). Fit the gear over the flywheel with the lead-in on the teeth facing towards the front of the flywheel and allow the ring to cool.

To Refit the Flywheel

1. Using the method of removal but in reverse, mount the flywheel to the crankshaft flange so that the untapped hole in the flange is in line with the seventh unused smaller hole in the flywheel.

2. Engage the securing setscrews with new hardened steel washers and tighten to a torque of 80 lbf ft (11,0 kfg m) -108 Nm. Where the flywheel is secured with place bolts, without washers, these should be tightened to 90 lbf ft (12,4 kgf m) - 122 Nm. Place bolts can be identified by the 6 slots cut in the head face and the embossed letter 'T'.

3. Set up a clock indicator gauge with the base secured to the flywheel housing or cylinder block and adjust the clock so that the stylus is contacting the flywheel periphery. Turn the crankshaft and check the total reading. The flywheel should run true within 0.012 in (0,30 mm) total indicator reading.


4. Now adjust the clock gauge so that the plunger is at right angles to the crankshaft flange and rests on the vertical machined face of the flywheel, at the outermost point of the face (Fig. P.1).

Press the crankshaft one way to take up the end float, and turn the flywheel. The run-out on the flywheel face should be within 0.001 in (0,025 mm) per inch (25 mm) of flywheel radius from the crankshaft axis to the clock gauge stylus. If not, remove flywheel and check mating faces for burrs and dirt.

5. Lock the setscrews with the tab washers where fitted.

6. Refit the clutch and gearbox, etc.

To Remove the Flywheel Housing

1. Remove the flywheel.

2. Unscrew the nuts or setscrews securing the flywheel housing to the cylinder block and tap the housing clear of the locating dowels.

3. Examine the housing for cracks and damage etc

To Refit the Flywheel Housing

1. Fit the housing to the cylinder block.

2. Refit the securing nuts or setscrews.


3. Check concentricity (Fig. P.2.) The inner bore of of the flywheel housing must be truly central with the crankshaft within the limits listed overleaf.


4. Check perpendicular alignment (Fig. P.3). This facing should be within the limits listed below.

Diameter of Housing Allowance

Up to 141/4 in (362 mm) 0.006 in (0,15 mm) Total Indicator Reading.

141/4 in to 201/8 in (362 to 511,18 mm) 0.008 in (0,20 mm) Total Indicator Reading.

201/8 in to 251/2 in (511,18 to 647,70 mm) 0.010 in (0,25 mm) Total Indicator Reading.

251/2 in to 31 in (647,70 to 787,40 mm) 0.012 in (0,30 mm) Total Indicator Reading.

5. All adjustments to bring the flywheel housing within the above limits must be carried out on the flywheel housing and under NO CONDITIONS must the rear face of the cylinder block be interfered with.

6. When the housing is properly aligned to the above limits, tighten the securing nuts evenly.

7. Refit the flywheel (Page P.1).

Oil Seal for Fluid Drive

Engines which transmit power through a fluid drive have a sealed back end arrangement consisting of spring loaded rubber seal fitted in the engine backplate which locates around a spigot on the front face of the flywheel.

When fitting this seal, ensure that the lip of seal is towards the flywheel and the back of the seal is fitted flush with the front face of the backplate.