CAP 0952005 - Caterpillar

ENGINES
AGRICULTURAL TRACTORS
ARTICULATED TRUCKS
EXCAVATORS
MOTOR GRADERS
SKIDDERS
TRACK-TYPE TRACTORS
TRACK-TYPE LOADERS
WHEEL LOADERS
WHEEL-TRACTOR SCRAPERS
ALL CATERPILLAR MACHINES POWERED BY 3306 ENGINES;
ALL 3306 INDUSTRIAL, MARINE, AND GENERATOR SET ENGINES;
ALL 3306 TRUCK ENGINESReference: Service Magazine; June 14, 1993; Page 13; "Lock Removed From Front Timing Gear Group To Help Prevent Loss Of Tightening Torque". Service Magazine; June 14, 1993; Page 14; "New Fuel Pump Drive Idler Gear Assembly And Shaft Used In Front Timing Gear Groups".Problem:
There has been a recent increase in reports of front gear train failures. These failures have been the result of:* Loosening of the bolts and nut mounting the fuel pump drive idler shaft to the front of the cylinder block.* Idler gear sleeve bearing flaking.This surge in failure reports may be related to the:* Higher fuel pump injection pressures that are needed for the reduced emissions requirements of recent years.* From the mixing of vintages of idler shafts and idler gear bearings.Solution:
Engine Engineering is continuing to work on long term improvements to this problem, but for the short term, when the front housing has been removed for any reason, or after a gear train failure, take the following steps to minimize the possibility of the shaft mounting bolts/nut loosening or the idler bearing failures occurring: 1. Remove the two 0S-1618 Bolts (8) and 8N-4960 Plate (7) securing the fuel pump idler gear (6) to the idler shaft (3), and remove the idler gear assembly.2. Remove the two 0S-1594 Bolts (2) and the one 5B-9079 (4) Nut that fasten the idler shaft (3) to the front of the cylinder block and remove idler shaft.3. Inspect idler shaft mounting face and pilot for signs for wear. If the shaft does not have a "105-9772" part number stamped on the flange, or if the pilot diameter is worn below specification of 25.345 0.013 mm (.9978 .0005 in), replace with a new 105-9772 Idler Shaft. 4. Inspect condition of pilot bore for the idler shaft in front of cylinder block. The pilot bore should be 25.311 0.020 mm (.9965 .0008 in) in diameter and should not show signs of "wallowing out" of the bore.5. Inspect the condition of 5S-8462 Stud in front of cylinder block. The stud must be tight, and the threads must not be unusually worn. Replace stud if necessary. Put a light coat of 9S-3263 Thread Lock on the stud threads prior to installation.6. Reinstall 105-9772 Idler Shaft (3) in block. Be sure the idler shaft mounting flange is pressed flush against the front face of the cylinder block prior to installing the mounting hardware. You should note a tight fit when pressing the idler shaft pilot into the bore in the cylinder block. Use a soft-headed hammer or mallet to facilitate assembly.7. Put a light coat of 9S-3263 Thread Lock on two new 0S-1594 Bolt (2) threads and to the stud threads. Use a new 5B-9079 Nut (4) on the stud. Tighten the two 0S-1594 Bolts and one 5B-9079 Nut to a torque of 50 10 N