Check Valve may be Incorrectly Installed in the Cooling Fan Oil Return to Tank Line [TIBU3725]

HYDRAULIC SYSTEM

COOLER GP

Check Valve may be Incorrectly Installed in the Cooling Fan Oil Return to Tank Line

CONFIDENTIAL TIBU3725-02

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TECHNICAL INFORMATION BULLETIN	FEBRUARY 26, 2003
ARTICULATED TRUCKS	725 (AFX1-UP) (730 (AGF1-UP) THIS TIB REPLACES THE NOV. 6, 2002 ARTICULATED TRUCK TIB, COMPONENT CODE 5067. Ignore the former publications.
	Component Code 5067 5057

SUBJECT: Check Valve may be Incorrectly Installed in the Cooling Fan Oil Return to Tank Line

PROBLEM:

There have been reports of failures of the cooling fan system hydraulic oil cooler ? part number 122-6485. Investigation has revealed that the cooler core has failed due to high internal oil pressure. Further investigation revealed the cause of the high pressure to be a check valve incorrectly installed in the return to tank line from the fan hydraulic system.

SOLUTION:

Locate the return manifold. The return manifold is under the front left corner of the operator cab.

Illustration 1. Location of the return manifold

The current return manifold has a check valve and a straight adaptor that connects return hoses to the manifold at the inner face of the manifold.

Illustration 2. Correct Check Valve and Adaptor Locations. (1) Check Valve. (2) Straight Adaptor. (3) Chamfer on the Check Valve.

The check valve (1) should be in the forward port in the return manifold. The check valve is in the line for the steering system metering pump return.

The straight adaptor (2) should be in the rear port in the return manifold. The straight adaptor is in the line for the cooling system hydraulic fan return.

The check valve and the straight adaptor can be identified by visual inspection. The check valve has a chamfer (3) on the hexagonal sections. The straight adaptor is not chamfered.

Illustration 2 shows the difference between the check valve and the straight adaptor and their correct position in the return manifold.

If the check valve and straight adaptor are found to be in the incorrect ports, remove them and install them in the ports as shown in Illustration 2.

Illustration 3. Location of the check valve in the former return manifold

The former return manifold is shown in illustration 3. The check valve should be on top of the return manifold. The straight adaptor should be in the port on the side of the return manifold.

Report all findings of incorrectly positioned check valves and adaptors to any of the following AVSpare personnel.

Robert Murray (U.S.)

Phone:- 001 815 729 5432, e-mail:- [email protected]

John Chapman (U.K.)

Phone:- +44 (0)191 569 2614, e-mail [email protected]