PISTON AS 1976700 - Caterpillar

COLOR="#003D84">Product Support Program For Installing New Bolts And Washers For The Crankshaft Counterweights On Certain D11N Tractors; 776B Tractors; 777B, 785, And 789 Trucks; And 3508, 3512, And 3516 Engines
SMCS - 1231 PS4639
November 3, 1991
(Revised February 1993)
U-219
A-163
AU-143
B-44
E-150
O-165
TM-18 The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
This Program can be administered either before or after a failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS4639" as Part Number, "7755" as Group Number, and "96" as Description Code.
This Revised Service Letter replaces the November 3, 1991 (Revised December 1992) Service Letter. A change was made to Step 3 of the Action Required.
Termination Date
November 30, 1993Problem
The crankshaft counterweight bolts may fail at high hours on certain D11N Tractors; 776B Tractors; 777B, 785, and 789 Trucks; and 3508, 3512, and 3516 Engines.
Affected Product
Model & Identification Number
D11N (74Z1-725)
776B (6JC1-82)
777B (3NF1-42; 4YC1-1182)
785 (8GB1-406)
789 (9ZC1-313, 9ZC328, 9ZC329, 9ZC331)
3508 (1ZF1-517; 23Z1468-2818; 68Z735-755; 69Z332-511; 70Z604-719; 95Y704-758; 96Y754-1027; 97Y661-671)
3512 (4KC1-143; 3YF1-407; 49Y515-536; 50Y713-863; 51Y524-603; 24Z1723-2938; 65Z639-687; 66Z219-364; 67Z568-733)
3516 (3RC1-193; 4XF1-275; 9KF1-48; 25Z881-1715; 27Z660-674; 28Z618-621)
3516 (29Z843-913; 71Z253-281; 72Z347-391; 73Z206-301)
Parts Needed
Action Required
Remove and install one bolt and washer at a time.
Refer to the October 23, 1989 Service Magazine Article " New Crankshaft Counterweight Bolt And Washer Used"
1. Remove one of the existing 4W6358 Bolts and 9Y3830 Washers that hold the counterweights to the crankshaft.2. Put 6V4876 Molykote Paste on the threads, shank, and the surface of the new 7E42O1 Bolt that makes contact with the counterweight.3. Install the new bolt and washer. Tighten the bolt to a torque of 70 5 N m (50 4 lb. ft.).4. Tighten the bolt an additional 120 5 °5. Repeat Steps 1 through 4 for each remaining bolt and washer.Service Claim Allowances
D11N, 776B, 777B, 785, And 789
3508, 3512, And 3516 Engines
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.