Diagnostic Information on LL8 Engine Oil Leak from Rear of Crankshaft Due to Porosity (Follow Special Crankshaft Porosity Service Repair Procedure)

This bulletin is being revised to add the 2006 and 2007 model years. Please discard Corporate Bulletin Number 05-06-01-022A (Section 06 -- Engine/Propulsion System).

This bulletin is being published to aid technicians in the diagnosis and repair of oil leak from the rear of the engine. Some engines may have slight crankshaft casting porosity that results in a leak in the crankshaft flange bore. This leak may be misdiagnosed as a rear main oil seal leak.

Important: Do not assume that an oil leak at the rear of the engine is from a leak at the rear of the crankshaft.

Refer to above illustration for the area of the oil leak (1). Verify the leak by looking in the end of the crankshaft. If oil is present in the bore (where the torque converter nose engages the crankshaft), the special service procedure needs to be performed. If the bore is dry, or oil appears to be from the seal area, perform normal oil leak analysis. Refer to Oil Leak Diagnosis in SI.

A service cup plug was recently developed to repair this leak and is available through the Warranty Parts Center (WPC). Refer to the information in this bulletin to order a service cup plug.

Important: If the following tools are not available at your dealership, use an aftermarket equivalent.

Special Installation Tool Assembly Needed:

1. J 8433-3 Forcing Screw or Equivalent
2. J 45949 Bolts (Only the two bolts of this kit will be needed) or Equivalent
3. For Display Purposes Only (End Section of the Crankshaft)
4. 18 MM. or 19 MM. Impact Style Socket (Thick Wall) with a 1/2" drive base that is approximately 15MM. deep with an overall height of 38 MM. (1 1/2").
5. J 8433-1 Puller Bar or Equivalent

1. Verify the oil leak. Refer to the above illustration (1), showing the leak path through the end of the crankshaft flange bore area.
2. Order a crankshaft service cup plug part number WPC-340 by completing the WPC PART REQUEST FORM at the end of this bulletin and send it to the WPC via fax or E-mail. Typically, the cup plug should arrive within 2 business days.

•	Fax Number - 248-371-0192

•	E-mail Address -- warrantypartscenterusa@gm.com.

3. Clean the crankshaft flange bore area with BrakeKleen (12378392, 12346139 (in Canada, 88901247) or equivalent. Thoroughly dry the area and examine the bore surface for irregularities. If the bore surface needs additional cleaning, use sand paper, or equivalent, and clean as necessary.
4. Once the crankshaft bore surface is clean and smooth, apply a thin bead of LOCTITE™ 620, P/N 89021297 or Permatex 27010 High Strength Red Thread Locker Gel, P/N 88861429 (in Canada, 88861430), completely around the inside of the crankshaft flange bore.



5. Position the crankshaft service cup plug into the crankshaft flange bore with service cup plug, dish side out . Refer to the above graphic illustration (1) (dish side out) for the installation of the service cup plug.

Notice: Do Not use the impact socket with hammer to drive the service cup plug into place. Damage to the crankshaft thrust bearing may occur.




6. Refer to above illustration (1), showing the 15 MM. step inside the 18 MM. 1/2" drive impact style socket.



7. Refer to the above illustration (1), showing the 38 MM (1½" ) overall height of an 18 MM or 19 MM 1/2" drive impact style socket.

Important: It is best to use a thicker wall socket to equalize installation force with the following approximate dimensions.




8. Assemble the arbor, forcing screw, attaching bolts and socket. Refer to the illustration titled, Special Installation Tool Assembly Needed. Install the tool press assembly to the end of the crankshaft flange and position the socket and service cup plug into the bore of the crankshaft flange. Refer to the above illustration for proper tool set up before pressing the cup plug into the end of the crankshaft.

The forcing screw will fit inside an 18 MM or 19 MM end of the impact style socket with the 1/2" drive side of the socket facing the service cup plug. The forcing screw should bottom on the 15 MM step inside the socket. Refer to the above illustrations on 1/2" drive impact style socket dimensions.

9. Hand tighten the forcing screw into the socket, making sure that it is centered on the service cup plug.
10. Mark the forcing screw and arbor for reference, then tighten the forcing screw two complete turns and an additional 90 degrees or 1/4 turn more.



11. When completed, remove the installation tool assembly and confirm the installation depth of the service cup plug. Place a straight edge across the center of the crankshaft flange as the measurement point. Measure from the straight edge to the center of the installed cup plug. The depth of the installed cup plug should be 16-17 mm (0.63-0.67 in). Refer to the above illustration to confirm the installed depth.

For vehicles repaired under warranty, use:

For vehicles repaired under warranty, use:

IMPORTANT NOTE WHEN PRINTING THIS FORM: If the form prints out on two pages, make certain you fax BOTH pages so that the WPC receives all the needed information. Missing information will delay or prevent the part from being shipped.