0305378 JOHNSON BUSHING, Control gear

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 must be administered as soon as possible. When reporting the repair, use "PI3596" as the Part Number, "77511" as the Group Number, "56" as the Warranty Claim Description Code and "T"as the SIMS Description Code. Exception: If the repair is done after failure, use "PI3596" as the Part Number, "77511" as the Group Number, "96" as the Warranty Claim Description Code, and "Z" as the SIMS Description Code.
Completion Date
October 31, 1992Termination Date
July 31, 1993Problem
The fuel injector may not seal properly in the injector bore of the cylinder head(s) of certain 3508, 3512, and 3516 Engines. The injector bore needs to be machined on these engines.
Affected Product
Model & Identification Number
3508 (1ZF666-668, 23Z4193-4273,23Z4277, 23Z4279, 23Z4283-4290,23Z4292,23Z4293,23Z4295,23Z4300,23Z4303,23Z4304;95Y822-830;96Y1253-1270;97Y676;69Z592-594,69Z597;70Z807,70Z808)
3512 ( 24Z4352-4411,24Z4413-4420, 24Z4424-4442, 24Z4444-4446,24Z4448,24Z4451-4453, 24Z4456, 24Z4458, 24Z4459,24Z4462,24Z4463;50Y1020-1043;51Y670-672;65Z742-752 ; 66Z486-489;67Z928-959;3YF665-678;49Y664-666)
3516 (25Z2652-2663, 25Z2665-2712, 25Z2715-2722, 25Z2724-2730; 29Z1001-1005; 4XF419-424; 72Z438-440; 73Z545-548)
Parts Needed
Dealers will need to order parts for this Program.
1 - 6V1250 Seal2 - 8J8725 Seal Use as required. Quantities listed are per cylinder.
Action Required
Call Dave Bradshaw (ph. (317) 448-5590) to obtain a tool kit containing the tools necessary to rework the cylinder heads. After obtaining the tool kit, perform the rework according to the attached rework procedure.
Owner Notification
U.S. and Canadian owners will receive the attached Owner Notification.
Service Claim Allowances
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Make Every Effort To Complete This Program As Soon As Possible.
Attach.
(1-Owner Notification)(2-Rework Procedure)Copy Of Owner Notification For U.S. And Canadian Owners
Rework Procedure
Do not remove the cylinder heads from the engine to complete this rework.If the cylinder heads are stamped with "B" or "R".rework is not required. The "B" or "R" designates that the rework was already completed by the Lafayette Facility. The stamping is located on the cylinder head face.
A procedure and tool kit have been developed to rework the cylinder heads. Please contact Dave Bradshaw of 3500 Customer Service at telephone number (317) 448-5590 for information on how to obtain a tool kit. A list of the components in the tool kit follow.
Use the appropriate service manual disassembly and assembly module as a guide for removing and installing components in this procedure.
1. Identify all the components to be removed by cylinder number so they can be installed in the correct locations.2. Remove the valve cover.3. Remove the rocker arm assembly.4. Remove the fuel line between the fuel manifold and the cylinder head. Remove the unit injector.5. Check for carbon in the cylinder head injector bore, and on the injector's nozzle seat and bottom O-ring area. (See Illustration 1 for the areas to be cleaned.)6. If there is no carbon in the injector bore or on the injector, go to Step 9.7. If there is carbon in the cylinder head injector bore, clean the carbon from the nozzle seat area and "B" Bore. (See Illustration 1 for the areas to be cleaned.)A) Clean bore with fuel oil, bottle brush (Item 12 on Tool List), and Scotchbrite (Item 7 on Tool List). Use Scotchbrite on "B" bore only to assure good o-ring seal.B) Flush fuel holes (See Illustration 2) and injector bore with fuel oil.C) Remove excess fuel from the cylinder with differential suction tool (Item 10 on tool list).8. Clean carbon from the unit injector's nozzle seat and bottom O-ring area.A) Cover the injector fuel ports to keep out debris.B) Remove the bottom o-ring from the injector. (This is a 6V1250 O-Ring.)C) Clean carbon from the o-ring groove with fuel oil and Scotchbrite.D) Use fuel oil to clean debris from the outside of the injector.E) Remove the protective cover from the unit injector fuel ports.F) Install a new bottom 6V1250 O-Ring and two new upper 8J8725 O-Rings on the unit injector.9. Plug cylinder head "D" Bore (See Illustrations 1 and 3)with "D" Bore plugs (Item 13 on Tool List).A) Use T-wrench (Item 14 on Tool List) to install "D" Bore plug.B) Use the T-wrench to push the plug straight into the "D" Bore. Do not twist the plug into place.
10. Place guide bushing lock (Item 6 on Tool List) over the bridge dowel (See Illustration 4).11. Regulate the air supply to air tool (Item 1 in Tool List) to achieve 300 rpm at a no-load condition. Install the tool assembly (Item 2 on Tool List) in the chuck of the air tool.12. Insert the tool assembly into the cylinder head injector bore. Be sure the notch in the "A" Bore bushing (Item 4 on tool list and part of the tool assembly) is aligned with the guide bushing lock (See Step 10) on the bridge dowel.13. Bring the cutting tool (Item 3 on Tool List and part of the tool assembly) into contact with the chamfer and apply downward pressure before starting the air tool.14. Start the air tool and begin cutting.15. Apply steady, even pressure on the cutting tool so that the air tool's speed is maintained at 200 rpm. Maintain a uniform air tool speed.16. Continue to cut the chamfer until the stop collar (Item 5 on the Tool List and part of the tool assembly) contacts the guide bushing lock. (See Illustration 5.)17. Stop cutting when the air tool rpm picks back up to the no-load rpm. Excessive dwell will shorten the tool life.18. Remove the Tool Assembly from the cylinder head.19. Remove the Guide Bushing Lock from the bridge dowel.20. Vacuum the chips from the injector bore. Do not use a magnet to remove the chips.
21. Use the Depth Gauge (Item 15 on Tool List) to check chamfer depth.A) Make sure the chamfer is free of chips so the Depth Gage seats on the chamfer in the fuel injector bore.B) The chamfer depth is correct when the Depth Gage's "go/no-go" step is located as shown in Illustration 6. The top the Gage must be above the top plane of the bushing and