Technical Service Bulletins


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This bulletin applies to 2007-2013 GMC Yukon and Denali vehicles. A power steering fluid leak may be found from the power steering hose connection at the steering rack.

Based on parts returned to the Warranty Parts Center (WPC), replacement of both hose-to-rack “duckbill type” seals has corrected the condition. Replacement of the rack is not necessary for this issue.

Visually inspect the area where the hose connection occurs. Check the bolt securing the hoses to the steering gear for proper torque (106 in.-lbs.) before proceeding further. Clean the area around the connections, joints and seals with engine degreaser. Add fluorescent dye (such as Kent Moore GE 28431-6) to the power steering fluid.

Start the engine and allow the power steering system to reach normal operating temperature.  Turn the steering wheel to the stops in each direction while bumping the steering wheel against the stops 3-4 times. This will build maximum steering system pressure and will help to identify the source of the leak. Do not hold the steering wheel against the stops for more than 5 seconds, to avoid pump damage.

Verify that the source of the leak is actually the hose connection to the power steering rack. If the leak is at this connection, remove the bolt securing the hoses and replace the seals.

First, remove the chip cover from the truck frame, exposing the hose/gear connection. Remove the bolt fastening the connector plate to the gear housing using an 8 mm hex socket. Grasp the tubes, one in each hand, and pull out from the connection, wiggling slightly as you pull back.

If the seals remain in the gear housing, remove them using the Kent Moore J-42640 tool. Do not use a screwdriver or any other sharp-ended tool to remove the seals, as this can damage the housing bore.

Wipe the gear housing plate connection surface clean of any oil and debris. Place the replacement seal, P/N 26100863, in the counterbore and seat the seal using tool J-42640. Tap the seal into place until the seal is firmly against the bottom of the counterbore. Do this for both ports.

Grasp the hose tubes and align to the ports. Insert the tube ends until you feel them “snug up” in the seals. There will be a gap between the connection plate and the gear housing at this point. Do not allow the tubes to come back out of the housing ports.

Align the connection plate bolt through the hole in the plate. Insert the bolt to the gear housing’s threaded hole and start the threads by hand. Drive the bolt into the housing the remainder of the way using the hex socket and ratchet wrench. This will draw the tube ends into the ports and seat the connection plate. Tighten to 106 in.-lbs.

Start the engine and exercise the steering system several times to bring the oil to operating temperature and inspect for leaks.

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