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ure To Check Crankshaft Deflection
1202
3600 Family of Engines 

Reference: Engine News, August 1990, "Procedure To Check Crankshaft Deflection" 

Reference: Engine News Special Edition, SEBD9129-06, October 1999, "Product Support Update - 3600 Family of Diesel Engines" 

The information in the Reference Article has been updated. The complete article with the updated information follows. 

NOTE: The Reference (Engine News Special Edition) contains the correct information. 

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 and cause the crankshaft to deflect. This deflection can cause crankshaft and/or bearing failure. 

The crankshaft deflection must be checked after the final installation of the engines. The check can be made with the engine hot or cold. 

For engines driven from the rear, the deflection must be checked at the following connecting rod journals: 

* 3606 Engines - number 3 and number 6 
* 3608 Engines - number 4 and number 8 
* 3612 Engines - number 5 and 6, and number 11 and 12 
* 3616 Engines - number 7 and 8, and number 15 and 16 
For engines driven from the front, the deflection must be checked at the following connecting rod journals: 

* 3606 Engines - number 4 and number 1 
* 3608 Engines - number 5 and number 1 
* 3612 Engines - number 5 and 6, and number 1 and 2 
* 3616 Engines - number 7 and 8, and number 1 and 2 
The procedure that follows can be used to check crankshaft deflection. 

Checking Crankshaft Deflection (Bend)
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 just goes beyond the connecting rod. 

 
Location of bolt and nut. © 

3. For 3606 and 3608 Engines, where the counterweight is not available on both sides, install a 2B-7218 Bolt (1) with a 1B-4333 or 2J-3507 Nut (2) in the crankshaft. Tighten the nut against the crankshaft. The purpose of the bolt and nut is to provide a locating surface. 

4. Install a Starrett Crankshaft Distortion Dial Gauge No. 696 with Starrett No. 696B Balancer Attachment between bolt (1) and the counterweight. Put the dial gauge within 10 mm (.39 in) of the end of the counterweight. Turn the dial of the indicator to align the zero with the pointer. Turn the indicator on its end points until the pointer of the indicator will not move from zero. 

5. Turn the crankshaft in the direction of normal rotation until the indicator almost makes contact with the connecting rod on the other side of the crankshaft. 

NOTE: Do NOT let the indicator make contact with the connecting rod. 

6. The dial indicator reading must not change more than the value shown in the following chart for the approximate 300° 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. 

 

If the dial indicator reads more than the value in the chart, the cylinder block is distorted. Loosen the bolts that hold the engine mounting rails to the foundation mounting rails. Adjust the shims to make the engine straight again. Also check to see if the engine mounting bolts have enough clearance to let the engine expand as it gets hot.