Series 60 Gear Case Brackets

Detroit Diesel has introduced a product improvement, involving stabilization of the gear case/cover in Freightliner Trucks. This has been done to reduce vibration and extend thrust plate perimeter seal life. Our experience has also shown that in some cases, improving the stiffness in this area has also resulted in stoppage of thrust plate seal leaks. This service information letter provides details on how to implement this product upgrade on several different Freightliner vehicle configurations.

The hardware includes a new cast stabilizer bracket, 23528306, on the right side of the engine, replacing the former “L” stabilizer bracket, 8929760, along with various attachment bolts, clips, and clip bracket to attach the breather tube (Items 04 – 08 in figure 1). There is also a newly designed three-bolt bracket, 23528307, for the top left side of the engine, see figure 2. Both right and left side brackets, as well as attachment hardware, are included in kit number 23529492. A listing of kit contents is included with this service information letter (Attachment #1).

There are four (4) Freightliner vehicle configurations affected. They include: FLD-120 and Classic (Units with coolant crossover pipe), FLD-120 (Units without coolant crossover pipe), and Century. Each of these models requires specific bracket mounting instructions. The information below covers installation requirements for each vehicle model. Note, prior to removal of any hardware, steam clean the area between the gear case and cylinder head in the cam seal area, as well as the area around the intake manifold gasket. This will allow for identification of new oil leaks following servicing as well as ease of intake manifold loosening without gasket damage.


Install the right side stabilizer bracket, 23528306. Note that only one bolt is required to fasten the bracket to the cylinder head. Also be aware that the bolt attaching to the gear case should be tightened first, followed by the new M10 bolt 23511786 (43-54 lb-ft, 58-73 N-m), attaching the bracket to the cylinder head. Discard one of the two (2) former bolts used to attach the former stabilizer bracket to cylinder head. You will need one (1) of the former bolts to fasten the breather tube clip to the clip bracket, which should be located in the threaded hole where the former bracket second bolt was used, figure 1, item 08.

To install the left side bracket, 23528307, remove any obstructions to installation of the threebolt gear case/cover bracket. This would include items such as the cooling fan air supply line and associated wiring. Reposition these components to the next lower through hole in the gear case/cover. Use two new gear case bolts, 23528812 (55-60 lb-ft, 75-81 N-m), to mount the bracket to the gear case. Loosen the intake manifold bolts and pull manifold back slightly, so there is room to install bolt, 23528792, between the bracket and cylinder head. Carefully pull back the manifold, with guide studs J36107 installed, so as not damage the intake manifold gasket, since it will be reused. This will allow positioning of bracket, 23528307, see figure 3. Make sure the threaded bolt hole on the left side of cylinder head along the upper rim is free from debris. Add a small amount of grease to bolt, 23528792 (43-54 lb-ft, 58-73 N-m) prior to installation.

The procedure is the same as for the FLD-120 (Units with coolant crossover pipe) except that the fan pressure sensor needs to be relocated to the next lower through hole in the gear case/cover when installing the left side bracket.

The procedure is the same as the above except there is no need for the breather tube clip and clip bracket attachments when installing the right side stabilizing bracket. Also, there is no crossover pipe and attachment bracket on the left side of the engine. Therefore, you simply use the two (2) new bolts, 23528812, supplied in the kit for attaching the bracket to the gear case/cover as show in figure 4.

The procedure for installing the right side stabilizer bracket is the same as above. Regarding the left side bracket installation, the intake manifold design does not obstruct the bracket bolt installation so there is no need to loosen the intake manifold. However, as in the cases above, the bolt hole for mounting the bracket to the cylinder head needs to be cleaned out and grease put on the bolt prior to finger tight installation.

The clip for the air line to fan must be moved to the next hole lower on the gear case housing. The horizontal coolant fill line from the reservoir is supported in two places. The front support is tied to a cam cover bolt and the rear to a through bolt in the gear case housing. Remove the bracket from the cam cover and relocate it to an empty through hole below the three-point bracket location using the bolt from the coolant fill line discussed in the paragraph above.

The bracket upper bolt will be a new bolt, 23528812, supplied in the Kit, and located in the same crossover pipe bracket location. The lower bolt/stud, 23528813, and nut, 23521131, are used to attach the coolant fill line support arm. Tighten all gear case/cover bolts. Tighten the M10 bolt to head last. The final installation should look like that shown in figure 5.

Detroit Diesel Corporation will pay 1.0 labor hours for this installation. Other repair procedures for this leak condition will no longer be accepted. Indicate the primary failed part number 8929318 and failure code 042 (leaks) on the AFA claim.

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