1996/02/12 Caterpillar

Closed Engine Crankcase Breather System Maintenance And Repair {1317,1107}


914G (7ZM, 9WM) Wheel Loaders;
IT14G (8ZM, 1WN) Integrated Toolcarriers;
M312 (6TL),
M315 (7ML) Excavators;
PF-300B (6HM),
PS-300B (4PN) Compactors

Some of the 3054 Machine Engines in these machines are equipped with a closed breather system. The breather removes the combustion gases from the engine crankcase and directs the gases to the induction system.

An internal port in the rocker cover allows the crankcase gases to pass into the breather body through a foam filter (3). Then the gases flow through a series of baffle plates (6) and into the valve cover through holes at the bottom of the chamber for the baffles. A valve (1) controls the flow of gases which pass from the breather, through the plastic outlet elbow (4), to the intake manifold.

The valve cover and breather assembly are made of a composite material and should be removed and installed with care. The 3054 breather uses three baffle plates (6).

The chart and illustration identify the breather system components.

Identification of closed breather system components.

Maintaining the Engine Breather System


You must read and understand the warning and instructions contained in the Safety section of the Operation And Maintenance Manual, before performing any operation or maintenance procedures.


Do not use excessive force to remove the hose from the breather outlet elbow. If the elbow breaks away from the breather body, see Procedure To Repair The Connection For The Breather Outlet Elbow.

1. Release the hose clamp and CAREFULLY remove the hose from the breather elbow (4).

2. Remove the valve cover. (See the Service Manual)

NOTE: Use care not to damage the breather cover or breather body with a pry bar.

3. Remove the bolts and carefully remove the breather cover from the breather body. It may be necessary to use a suitable pry bar to remove the cover from the body of the breather. Be sure that the pry bar does not damage the cover or body. Remove and discard the gasket (5).

NOTE: The breather valve (1) should be replaced every 4000 hours of operation. The foam filter (3) should be replaced every 2000 hours of operation.

4. Release the clip retainers (2) on the breather valve (1) and push the valve out of the breather cover.

5. Remove and discard the foam filter (3).


To prevent damage to the breather valve, remove the valve before the cover is washed.


Ensure that all the cleaning fluid is removed before the breather is assembled.

6. Use a clean nonflammable solvent to wash the body of the breather, the cover, baffle plates (6), and the breather elbow every 2000 hours of operation. Thoroughly dry the components after cleaning.

7. Ensure that the holes in the bottom of the chamber for the baffle plates are not restricted. If necessary, clean the holes.


1. Install the baffle plates (6) into the grooves in the breather body.

2. Install a new foam filter (3) into the breather body.

3. Install a new valve (1) into the breather cover. Ensure that the clips (2) are engaged correctly.

4. Install a new gasket (5). The gasket is installed dry. Put the cover and valve assembly into position on the breather body. Loosely install the bolts. Tighten the bolts gradually and evenly to a torque of 3 N·m (27 lb in).


Do not use excessive force to fit the hose to the breather outlet elbow.

5. Check to be sure there is no restriction in the breather elbow or the breather hose. Carefully install the breather hose on the breather elbow (4). Tighten the hose clamps that fasten the hose to the elbow.

Procedure To Repair The Connection For The Breather Outlet Elbow


Thoroughly clean the inside of the breather body after it has been drilled.

1. Ensure that the breather body is secure. Use a 22.5 mm (.89 in) drill to drill to a depth of 10.0 mm (.39 in) to remove the broken connection of the outlet elbow. Thoroughly clean the inside of the breather body.

2. Thoroughly clean the contact faces of the elbow and the breather cover.

3. Replace the breather elbow (4). Ensure that the contact surface of the elbow connection has a rough finish. Put the elbow into position on the breather body.

4. Apply Permabond® E3524 adhesive (in accordance with the manufacturers instructions) to secure the elbow to the breather body.

Caterpillar Information System:

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