MANIFOLD 3858833 - Caterpillar

Caterpillar: Confidential Yellow
PSP TO CORRECT GOVERNOR SURGING ON 3406B TRUCK ENGINES PS0234 - US, CANADA, COFA, TRUCK TEPS - SEE SUPPLEMENT 85-03-29
  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.
PRODUCT SUPPORT PROGRAM TO CORRECT GOVERNOR SURGING ON 3406B TRUCK ENGINES (Parts Stock Action Needed), 1264, 1287, PS0234 U-14 AU-12 C-12 TT-3 See March 29, 1985 Problem Some drivers of trucks powered by the 3406B Engine may complain of "vibration", "bounce", or "rough ride". In some cases these complaints can result from engine governor surging under part load, part "throttle" conditions. A new governor housing and a new guide provide more oil flow to the dash pot, and a stiffer dash pot spring is used. See Illustration. These parts reduce the surging by giving improved dampening of the governor. They will not correct such complaints caused by the truck itself. See topic "Action Requested". Affected Engines And Parts Needed The ending engine serial number is not available. Engines that are eligible under this Program have serial numbers 7FB1-Up, and certain fuel injection pump group serial numbers. This number is stamped on the top surface of the injection pump housing near the fuel lines. Perform the "Action Requested" before any parts are ordered. The following Table (A) lists only the new, improved parts needed. All the remaining parts in Table (B) should be installed. All injection pump groups with serial numbers below 32814 need all the parts listed in Table (B). (SEE ILLUSTRATION) Affected Parts - TABLE (B) 1 - 7W4247 Housing Assembly * 1 - 5F9144 Seal 1 - 7W4882 Spring (Dashpot) * 1 - 6H9691 Seal 1 - 7W4182 Body * 2 - 2W5447 Gasket 1 - 8N9384 Gasket 1 - 3L6768 Seal 2 - 7N8821 Ring 1 - 5P6620 Seal 1 - 6V5029 Seal 1 - 335879 Seal 1 - 8N3763 Gasket 1 - 5P5601 Seal 2 - 1J9671 Seal 1 - 8N6680 Screen Assembly 1 - 8N3765 Gasket 1 - 2D6392 Seal 1 - 8N3761 Gasket 1 - 8N9382 Gasket * New parts - the housing assembly includes improved guide. Action Requested (Parts Stock Action Needed) Effective analysis of this problem is difficult because many things in a truck can cause complaints of "vibration", "bounce", or "rough ride". Governor surge occurs only when the governor is at low load, part throttle, usually at 10 psi (70 kPa) boost or lower. It cannot occur when the rack is solid