SWITCH GP-TOGGLE 3T4405 - Caterpillar

3508, 3512, And 3516 Commercial EnginesDescription of Change: New engine cylinder blocks are now used. These new cylinder blocks are made from a higher tensile strength alloy. The new cylinder blocks will help prevent top deck cracking. Adaptable To: The service part numbers of the new cylinder blocks is provided in Chart A. The service part numbers are NOT on the blocks. However, a casting part number is located on the upper left rear corner and upper right front corner of the block. Illustration 1 shows a typical location of the casting part number.
Illustration 1. Location of Casting Part Number (A). Location of Mapleton Pour Code (B) There are some cylinder blocks with casting numbers that end in -0 and -1 which are also made with the stronger alloy material. These cylinder blocks can be identified by the Manufacturing Sequence Number (MSN). The MSN can be seen without disassembling the engine, and is a fairly accurate indicator of whether or not the block is made of the stronger alloy material. The MSN is located on the right side head face in front of cylinder number one. See Illustration 2.
Illustration 2. Location of Manufacturing Sequence Number (C) on the cylinder block.The MSN consist of two digits (NN), an alpha character (A), a space and a three digit number (XXX). The MSN can be interpreted as follows: NNA XXX * (NN) is a numeric order number (NOT THE YEAR)* (A) is an alpha character (A = 3508, B = 3512, C = 3516)* (XXX) is a numeric character ranging from 001 to 999
If the MSN comes after the number given in Chart B, then the cylinder block is made of the stronger alloy material.
The most positive indicator of when a cylinder block is made from the stronger alloy material is the Mapleton Pour Code (MPC). The MPC is located on the upper left rear face of the cylinder block. On an assembled engine, it is necessary to remove the left side camshaft access cover to view the MPC. It may also be necessary to rotate the gear to read all of the MPC.
The MPC consist of four digits (NNNN), a space and two alpha characters (AA). The MPC starts over each year. The MPC can be interpreted as follows: NNNN AA * (NNNN) is a numeric character* (AA) is an alpha character indicating a year using the NUMERALKOD (see Chart C)
If the MPC is after the code listed in Chart D, the cylinder block is made of the stronger alloy material.