MONITOR & MOUNTING GP 3375782 - Caterpillar

(4FD, 1RK),
G3408 (6NB, 6RJ, 3WR, 8YR),
G3412 (7DB, 3NK, 6ZM, 9RR) EnginesReferences: Engine News, March 1998, Page 8, "New Piston Cooling Jet Tube Assembly Provides Increased Piston Clearance".
Engine News, December 1998, Page 2, "New Piston Cooling Jet Tube Assemblies Provide Increased Piston Clearance For Engines With Gallery Cooled Pistons".
The initial change (see the first Reference Article) was made to provide adequate clearance between the piston skirt and cooling jet tube assembly. This change applied to all G3400 Engines equipped with gallery cooled pistons.
There was some confusion when the new piston cooling jet tube assemblies were released because diesel engineering made a change to the piston cooling jet mounting pads on the G3406 Cylinder Block. This change was made to increase oil flow around the mounting bolt. The result was a different piston cooling jet tube assembly and bolt for the G3406 Engine than the piston cooling jet tube assembly and bolt used on G3408 and G3412 Engines. The G3406 Engine uses the 155-4011 Piston Cooling Jet Tube Assembly with the 151-5925 (7/16 in) Bolt. This change is effective with G3406 (4FD1558-Up and 1RK87-Up) Engines. See Chart A.
G3406 (4FD1-1557 and 1RK1-86) Engines should use 155-4010 Piston Cooling Jet Tube Assemblies if the engine is fitted with Gallery Cooled Pistons. The 155-4010 Piston Cooling Jet Tube Assemblies should be used on all G3408 and G3412 Engines that are fitted with gallery cooled pistons. See Chart B for the effectivity of Gallery Cooled Pistons.