1997/01/27 Caterpillar

VIMS Exhaust Temperature Sensor Is Improved {7601,1919}

Usage:

5130 (5ZL, 7TJ),
5230 (7LL) Excavators;
784B (5RK) Tractors;
785B (6HK),
789B (7EK),
793B (1HL),
793C (4AR) Trucks;
994 (9YF) Wheel Loaders

Description of Change:

VIMS can report exhaust system temperatures that differ from the actual exhaust system temperature. Two improvements reduce the causes of temperature errors.

1. A design change to the internal electronics of the buffer makes it easier for the supplier to make a quality sensor. The buffer converts the temperature sensor (thermocouple) output into a PWM (Pulse Width Modulated) signal.

2. An improved design in the exhaust riser couplings reduces exhaust leaks that can cause the sensor electronics to fail. The PWM temperature sensor has electronic components that are affected by heat from various sources. As the temperature of the buffer exceeds 250 degrees F., the signal can fault into an FMI 03, 04 or 06. Temperatures in excess of 250 degrees F. can cause a temporary and sometimes permanent sensor failure. A temporary failure will allow the sensor to again work properly as it cools down.

Adaptable To:

An improvement to the buffer design on the 3E-7826 Exhaust Temperature Sensor will be available in mid-January. This improvement will show as Change - 04 on the sensor.

For engines in 793 trucks (3SJ1-56) and 793B trucks (1HL1-380), install the repair kit for exhaust riser leaks. The parts, installation instructions, warranty claim and parts disposition are described in Caterpillar Service Letter SEBE5869.

Caterpillar Information System:

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1997/01/27 C-V (U) Joint Life Extended Through Correct Operation Of The Differential Lock {3274,2453,3259,3260,3264}

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1997/01/27 New Control Lever Group Requires Spacer {1265,3209,5258}

1997/01/27 Hydraulic Hose Retention For Vibratory And Drum Propel Systems Improved {5057}

1997/01/27 Verify Offset Dimension When Ordering New Wheel Assembly {4209,4202}

1997/01/27 New Brake Bleeding Procedure {4250,4293}

1997/01/27 Solution To Cab Window Fogging {1818,7309,7310,7320}

1997/01/27 Special Instruction REHS0006 Available For Installation Of Output Yoke And Screen Housing On Remanufactured Transmissions {3159,3002}

1997/01/27 Remote Lubrication Lines Used To Lubricate Upper Hoist Cylinder Pins {7510,7258,5102}

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1997/01/27 Use Of Windows Write (Or Notepad) And Paintbrush For Taking Field Notes {0785,7601}

1997/01/27 Field Repair Of Single Wire Breaks In Harnesses {1408}

1997/01/27 Premachined Valve Seat Inserts And Precision Valve Guide Increase Valve Life {1103,1104}

1997/01/27 Points To Remember When Replacing A Viscous Crankshaft Damper Assembly With A Rubber Crankshaft Damper Assembly {1205}

1997/01/27 Checking The Alignment Of Timing Gear Marks {1206}

1997/01/27 Engine Oil Recommendation For 3408E (99C) And 3412E (80M) Engines {1318}

1997/01/27 125-0200 Camshaft Pilot To Remove And Install 106-4584 Camshaft {1202}

1997/01/27 128-3102 Tap Assembly And 128-3104 Stud Puller To Remove Injector Sleeves With Oversized Lower Bore {1125}

1997/01/27 Cylinder Head Stress Plate Used During Cylinder Bore Honing And Measurement {1223}

1997/01/27 127-1069 Timing Pin Used To Set Piston At 100° BTDC When Testing And Adjusting Fuel Systems {1250}

1997/01/27 127-5090 Coupling Socket For Removing And Installing The Implement Hydraulic Coupling Sleeve {5051,5051}

1997/01/27 Service Tools For Disassembly And Assembly Of All Wheel Steer Rear Axle {3254,3258,3260,4084,4321}