2010/06/10 Caterpillar

Engine:

All 3600 Engines

All C280 Engines

Engine News SEBD9646, 26 April 2010, "Procedure To Check Crankshaft Deflection". The article has been revised for engines that drive equipment from the front.

The crankshaft can be deflected (bent) if the installation of the engine is not correct. If the engine mounting rails are not fastened correctly to the foundation mounting rails, the cylinder block can twist or bend. The crankshaft to can deflect. This deflection can cause crankshaft and/or bearing failure.

The crankshaft deflection must be checked after the final installation of the engine.

For engines that drive equipment from the rear, the deflection must be checked at the connecting rod journals that are listed in Table 1:

Table 1

Number of Engine Cylinders	Cylinder Journal to Check
6 Cylinder	3 and 6
8 Cylinder	4 and 8
12 Cylinder	5 and 6, 11 and 12
16 Cylinder	7 and 8, 15 and 16

For engines that drive equipment from the front, the deflection must be checked at the connecting rod journals that are listed in Table 2:

Table 2

Number of Engine Cylinders	Cylinder Journal to Check
6 Cylinder	3 and 1
8 Cylinder	4 and 1
12 Cylinder	5 and 6, 1 and 2
16 Cylinder	7 and 8, 1 and 2

Checking Crankshaft Deflection

Illustration 1	g00605226
(1) Bolt (2) Nut (3) Dial gauge

1. Remove the appropriate inspection cover from the cylinder block.

2. Turn the crankshaft in the direction of normal rotation until the center of the counterweights barely go beyond the connecting rod.

3. For in-line engines, install a 2B-7218 Bolt with a 1B-4333 Nut or 2J-3507 Full Nut in the crankshaft. Tighten the nut against the crankshaft. The bolt and the nut are used to provide a locating face.

4. Install a Starrett Crankshaft Distortion Dial Gauge No. 696 and a Starrett No. 696B between the bolt and the counterweight. Put the dial indicator within 10 mm (0.39 inch) of the end of the counterweight. Turn the dial of the dial indicator in order to align the zero with the pointer. Turn the dial indicator on the end points until the pointer of the dial indicator will not move from zero.

5. Turn the crankshaft in the direction of the normal rotation until the dial indicator almost contacts the connecting rod. This connecting rod is on the other side of the crankshaft.

   Note: Do not allow the dial indicator to contact the connecting rod.

6. The dial indicator reading must not change more than the appropriate value that is given in Table 3 for the approximate 300 degrees of crankshaft rotation. Now turn the crankshaft in the opposite direction to the starting position. The dial indicator must now read zero. If the dial indicator does not read zero, do the procedure again.

Table 3

Maximum Acceptable Dial Indicator Readings
Front and Rear Cylinders	Middle Cylinders
0.18 mm (0.007 inch)	0.08 mm (0.003 inch)

If the dial indicator reads more than the value that is given in Table 3, the cylinder block is distorted. Loosen the bolts that hold the engine mounting rails to the foundation mounting rails. Adjust the shims in order to straighten the engine. Ensure sufficient clearance for the engine mounting bolts in order to allow the engine to expand as the engine gets hot.