A New Turbocharger Boost Pressure Regulator Needs To Be Installed On Certain 793 And 793B Trucks Caterpillar

NOTE: 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.

NOTE: This Program must be administered as soon as possible. When reporting the repair, use "PI3797" as the Part Number, "7751" 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 "PI3797" as the Part Number, "7751" as the Group Number, "96" as the Warranty Claim Description Code, and "Z" as the SIMS Description Code.

Completion Date

Termination Date

Problem

A new turbocharger boost pressure regulator needs to be installed to provide improved engine performance on certain 793 and 793B Trucks.

Affected Product
Model & Identification Number

793 (3SJ1-56(that have been converted to Electronic Fuel Injection))

793B (1HL1-312)

NOTE: 3516 Engines in dealers' exchange stock within the following serial number ranges may also update with this rework:

3516 2PK1-813

7CL1-183 (Remanufactured Engines)

54Z1-1110 (that have been convertd to Electronic Fuel Injection)

6CL1-150 (Remanufactured Engines that have been converted to Electronic Fuel Injection)

Parts Needed

Dealers will need to order parts for this Program.

2- 2B0941 Spacer

1 - 3D7587 Elbow

1 - 8D4755 Regulator

1 - 3E3510 Manifold

1 - 8F2396 Grommet

2 - 5H4778 Elbow

5 - 3J1907 Seal-O-Ring

1 - 7J4026 Elbow

1 - 9J2609 Hose Assembly

4 - 4K8864 Clip

1 - 0L1143 Bolt

4 - 7L0520 Stud

8 - 5M2894 Washer-Hard

4 - 2N2766 Locknut

2 - 4P0707 Clamp Assembly

1 - 4P7581 Clip

1 - 4P8134 Clip

2 - 5P8998 Nipple-Pipe

1 - 0S0509 Bolt

3 - 0S1594 Bolt

1 - 3S6115 Tee

2 - 8S9191 Bolt

1 - 9S4182 Plug-O-Ring

3 - 9S8004 Plug-O-Ring

3 - 9S8752 Nut-Full

2 - 0T0065 Bolt

1 - 7T9074 Valve-Solenoid

3 - 8T8729 Pin

3 - 8T8737 Plug

2 - 6V5048 Seal-O-Ring

1 - 7W6492 Plug-Pipe

40 - 9X6772 Strap-Cable

1 - 307947 Elbow

1 - 1028803 Terminal Kit

1 - 1036091 Sensor Assembly

1 - 1094591 Valve Group Solenoid

1 - 1138190 Hose Assembly

1 - 1196347 Harness Assembly

1 - 1236911 Harness Assembly

1 - 1236912 Harness Assembly

1 - 1248687 Control Group

Action Required

See the attached procedure.

Owner Notification

U.S. and Canadian owners will receive the attached Owner Notification.

Service Claim Allowances

NOTE: This is a 10-hour job.

NOTE: U.S. and Canadian Dealers Only - Eligible dealers may enter a Type 2 SIMS Report.

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

NOTE: The wastegate on the 793B EUI engine has been changed to have better opening and closing control. This will provide a better match between boost and the fuel rate. The 1116118 Waste Gate has not changed, but is now controlled by the ECM. The air that drives the wastegate to open has also been changed from engine boost to truck air that is supplied by the engine mounted air compressor. In earlier engines, a wastegate orifice was used to limit the maximum amount of exhaust gasses that bypassed the turbos when the wastegate was open. With the Smart Wastegate an orifice plate is not used because the wastegate itself controls the amount of exhaust gasses that are bypassed.

NOTE: Before beginning this Program, make sure PI3718, Service Letter dated September 8, 1994, has been performed.

Reference Publications:

1. Service Magazine, December 12, 1994: "New Exhaust Bypass Valve (Wastegate) Used in Exhaust Bypass Group".

2. Service Magazine, September 26, 1994: "Maintenance Guidelines for Exhaust Bypass Group" (and supplement October 17, 1994).

3. Service Magazine, August 7, 1995: "Selecting the Correct Turbocharger, Wastegate Orifice, and Personality Module".

4. Special Instruction, SEHS9868, "New Personality Modules for 3500 EUI Engines Used in Off Highway Trucks"

5. Service Magazine, April 17, 1995: "Move Turbocharger Boost Sensor Block to Allow Relocation of Air Compressor Inlet Hose"

6. Service Magazine, August 15, 1994: "Switches With Screw Terminal and Sure Seal Connector Replaced By Switches with a DT Connector".

7. Service Magazine, August 22, 1994: "Procedure to Modify 4P4866 Coupling and 4P4864 Housing to Work with New High Pressure Turbochargers".

1. Remove the existing boost line between the wastegate and the intake manifold as in Illlustration 1. Remove the 8N9072 Valve Body and replace it with a 7W6492 Pipe Plug.

Illustration 1

2. The Smart Wastegate has a 1094591 Control Valve Group that will be mounted on the 3E3510 Manifold. This manifold must be mounted to the right hand side of the turbocharger support frame with two bolts. Drill two 0.5 inch holes as shown in Illustration 2.

NOTE: On a few newer engines, holes have already been drilled and tapped in the turbocharger support frame in this location for mounting the 3E3510 Manifold. If the tapped holes are already present, do not drill them out to 0.5 inches. The appropriate bolt is offered in the next step whether the holes are drilled out to 0.5 inches or tapped to -16.

llustration 2

3. Convert the existing 4P4862 Wastegate Group to a 1170062 Wastegate Group as shown in Illustrations 3, 4, 5 and 6. Both groups contain the same basic 1116118 Wastegate. See Reference Publications 1 and 2 for more information on the 1116118 Wastegate.

NOTE: The 3E3510 manifold has two 10.5 mm diameter bolt holes, five No. 6 O-ring ports, and one -16 UNF threaded hole. Mount the manifold as shown in Illustration 3 with the -16 threaded hole pointing to the front of the engine.

The chart below lists the items needed (and their location on Illustrations 3, 4, 5 and 6) to convert the 4P4862 Wastegate Group to a 1170062 Wastegate Group:

Illustration 3

Illustration 4

Illustration 5

Illustration 6

4. The chart above and Illustration 7 show the items and repair part information for the 1094591 Smart Wastegate Control Valve, and for assembly torques. To install the 1094591 Control Valve into the 3E3510 Manifold, first remove the outer nut that is shipped finger tight. Then remove the coil assembly to gain better access to the inner nut on the cartridge assembly.

Install the cartridge assembly into the - 16 threaded hole in the 3E3510 Manifold. Tighten the cartridge into the manifold using the inner nut to 50.0± 5.0 Nm. Install the coil and outer nut on the cartridge assembly. Rotate the coil assembly to the best position and tighten the outer nut to 20.0 ± 2.5 Nm.

The chart above lists the items needed to repair the 1094591 Solenoid Valve Group

Illustration 7

5. In the 3E8667 Electronic Control Group, the new 1248687 Personality Module replaces the 1193357 Personality Module which was used on 793B engines with either the 1141980 or 122035 Low-Pressure Turbocharger. The new 1248687 Personality Module also replaces the previous 1107479 Personality Module which was used with the 4P4646 Low-Pressure Turbocharger. The new 1248687 Personality Module can be used with any low pressure turbocharger.

The Smart Wastegate should only be used on an engine with 56 trim high-pressure turbochargers. The following high pressure turbochargers are 56 trim: 1064557, 0R6757, 1213850, or 0R6966. If the engine has either 4P4693 or 1098925 Turbochargers, they must be updated to 56 trim turbochargers. See Reference Publication 3 for more information.

If the new 1248687 Personality Module is installed prior to converting to the engine to the Smart Wastegate, the Smart Wastegate feature must be deactivated with an ECAP with an SPM version 1.3. To make this change go to the Read/Change parameters screen and follow the instructions to deactivate the Smart Wastegate function.

6. In the 9Y8911 Turbocharger Group, the wastegate orifice must be removed. See Illustration 8 for the location of the wastegate orifice plate. Also if the engine still has an unmodified 4P4864 Housing, it must be modified or changed to a 1054321 Housing before installing the Smart Wastegate. See Reference Publication 7 for more information.

Illustration 8

7. The 7E6505 Wiring Group and the 1170053 Sensor Group have been combined and replaced with the new 1214130 Wiring Group. A major change within the new 1214130 Wiring Group is the engine wiring harness has changed from 1061772 to 1196281 to accommodate the Smart Wastegate.

The new 1196281 Wiring Harness has the following changes to accommodate the Smart Wastegate:

The 6V1944 (low boost) Sensor and 1051875 (high boost) Sensor are replaced with a single new 1036091 Sensor. See Reference Publication 4 for more information on how to make this change. The new boost sensor uses a DT connector and has an expanded range. The previous sensors used an HD-10 connector. If the boost sensor block has not yet been relocated to the left front of the engine as viewed from the front of the engine, see Reference Publication 5 for more information.

To make sure the Smart Wastegate does not drain the truck air supply when the engine is off, a shutoff valve-solenoid is used to completely shut off the air supplied to the Smart Wastegate control valve when the key switch is off.

The new 1196281 Wiring Harness also has the following changes but these changes do not involve the new Smart Wastegate: