154-3730 Crankcase Breather Assembly Caterpillar

Problem:

The 154-3730 Breather Assembly (1) bolts to a 151-2617 Elbow Assembly (6) with a 6V-8676 O-Ring Seal (2) in the seal ring groove on the elbow assembly. See the illustration. This joint sometimes seeps oil soon after the engine is placed in operation. The cause of the leak can be one or more of the following:

* The hole in the breather assembly is too large and does not properly cover the o-ring seal.

* The sealing face of the breather assembly is not flat enough for the O-ring to seal properly.

* The mounting studs, which are spot welded in the breather assembly, have distorted the sealing surface.

* Paint on the mounting surface forms an irregular surface and interferes with a proper oil seal.

These problems can randomly occur on any 154-3730 Breather Assembly in the field.

Solution:

1. Remove nuts (3) and washers (4) from studs (5). See the illustration.

2. Remove the 154-3730 Breather Assemblies (1) from the 151-2617 Elbow Assembly (6).

3. Check the condition of the 6V-8676 O-Ring Seals (2) in the grooves on top of the 151-2617 Elbow Assembly.

4. Be sure the contact surfaces of the breather assemblies and elbow assembly are clean and free of any foreign material.

5. Apply a bead of 4C-9613 RTV Silicone (Clear) General Purpose Sealant around the center hole in the mounting face of the breather assemblies.

6. Put the breather assemblies in position on the elbow assembly. Install the washers (4) and the nuts (3) on the breather assembly studs (5). Tighten the nuts to the standard torque.

154-3730 Breather Assembly (1).

6V-8676 O-Ring Seal (2).

9S-8752 Nut (3).

5M-2894 Washer (4).

Stud (5).

151-2617 Elbow Assembly (6).

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