2000/12/01 Caterpillar

Engines: Commercial

3500 Diesel

Engine News SEBD9264, September 1998, "Recommended Lubrication And Torque Procedure For Crankshaft Counterweight Bolts". Disregard this article. This article has been replaced by the following article.

Reference: Engine News, July 1998, Page 7, "New Counterweight Bolt Assembly Replaces Bolt And Washer"

Reference: 3500 Series Guideline for Reusable Parts and Salvage Operations, SEBF8156, "Specifications for Crankshaft Measurement for 3500 Family of Engines"

Reference: 3500 Series Guideline for Reusable Parts and Salvage Operations, SEBF8301, "Inspection and Reuse of Critical Fasteners Used in All Engines"

Note: Before removing a crankshaft counterweight, check for a legible sequence number on the counterweight. If a legible sequence number is not found, mark the sequence number on the counterweight. Counterweights should be numbered in sequence. These sequence numbers start at the front of the engine on engines with standard rotation. The sequence numbers start at the rear of the engine on engines with reverse rotation. Always reinstall the counterweight in the counterweight's original location.

At every major engine overhaul, always remove the crankshaft counterweight and replace the counterweight bolts. After the counterweight is removed, closely inspect the contact surfaces between the crankshaft and the counterweight. Please refer to the 3500 Series Guideline for Reusable Parts and Salvage Operations, SEBF8156, "Specifications for Crankshaft Measurement for 3500 Family of Engines" for checking the crankshaft. New counterweight bolts must be used to reattach counterweights. Do not reuse the counterweight bolts. If a counterweight bolt is removed, that counterweight bolt must be replaced with a new bolt. See Tables 1 and 2 in order to identify the proper counterweight bolt.

Table 1

Required Parts For A Bolt Hole with A Diameter Of 27 mm (1.06 inch) In The Counterweight
Part Number	Description
7E-4201	Bolt
7E-4725	Washer

Table 2

Required Parts For A Bolt Hole With A Diameter Of 32.5 mm (1.28 inch) In The Counterweight
Part Number	Description
128-4845	Bolt Assembly

The quality of the joint between the crankshaft and the counterweight depends on the proper amount of bolt stretch of the counterweight bolts. The amount of bolt stretch is determined by the tightening torque that is applied to the bolt. The amount of bolt stretch can be affected by the type of thread lubricant that is used on the bolt. The only acceptable thread lubricant for counterweight bolts is 6V-4876 Lubricant (Molykote). The use of any other type of thread lubricant on the counterweight bolts may result in improper bolt stretch. This could decrease the quality of the joint between the crankshaft and the counterweight. The use of an incorrect thread lubricant could result in damage to the counterweight bolt or the threads in the crankshaft.

Procedure For Tightening The Counterweight Bolts In 3508 and 3508B Engines

1. Prior to assembly, put 6V-4876 Lubricant (Molykote) on the bolt threads, the bolt shank, and the underside of the bolt head. Do not use any other lubricant on the bolt threads.

2. Tighten the bolts evenly to a torque of 200 ± 5 N·m (145 ± 4 lb ft).

3. Loosen the bolts.

4. Tighten the bolts evenly to a torque of 70 ± 5 N·m (50 ± 4 lb ft).

5. Put a mark on each bolt head. Tighten each bolt more for 120 ± 5 degrees.

Procedure For Tightening The Counterweight Bolts In3512, 3512B, 3516, and 3516B Engines

1. Prior to assembly, put 6V-4876 Lubricant (Molykote) on the bolt threads, the bolt shank, and the underside of the bolt head. Do not use any other lubricant on the bolt threads.

2. Tighten the bolts evenly to a torque of 70 ± 5 N·m (50 ± 4 lb ft).

3. Put a mark on each bolt head. Tighten each bolt more for 120 ± 5 degrees.