Engine / Allison transmission alignment

mojito5000

New member
Aug 19, 2019
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Oregon
I'm mid-way through getting my Duramax back going again. Pulled the old motor, swapped out wiring harness, intake manifold, and all the other fun bits from my '01 lb7 to the new '03 lb7. The engine is in the truck, but for the life of me, I can't get the transmission to mate with it correctly. To the best of my knowledge, I don't think anything shifted since I pulled it a week ago.

From what I can see, the engine is sitting slightly off-kilter, and the flexplate is hitting on the transmission pin that's on the drivers side. I've tried using a jack to rotate the engine, but it doesn't seem to align fully. I probably spent about 3 hours on this damn thing today with nothing working out.

Am I missing something?
 

mojito5000

New member
Aug 19, 2019
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Oregon
I hope these help, if I can take other pictures to help illustrate the problems let me know what you’d like to see.
Thanks!

7D04B489-F4E2-4413-B9A8-B84A537F18D8.jpegE04A4250-884A-4A7D-BCB8-8BFDBA6C9A3D.jpeg
 

ironmax

chock full of goodies
Jul 6, 2010
455
4
18
Col. Ohio
I hope these help, if I can take other pictures to help illustrate the problems let me know what you’d like to see.
Thanks!

View attachment 104091View attachment 104092
I would make shure your torque converter is fully seated. Should of felt three separate depths. If you didn't remove the converter and assumed it stayed in its fully seated position this could be your problem. It dosent take much for them to slide out when tilted.
 

mojito5000

New member
Aug 19, 2019
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1
Oregon
I would make shure your torque converter is fully seated. Should of felt three separate depths. If you didn't remove the converter and assumed it stayed in its fully seated position this could be your problem. It dosent take much for them to slide out when tilted.
Thanks! I pulled it out again, checked the converter and it seemed seated. This time I took off the motor mounts and was able to get them to mate. Thanks for the reply! Now onto final assembly
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
13,342
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Mid Michigan
Looks like you simply didnt have the transmission at enough of an angle for the engine to match up. Glad you figured it out.
 

mojito5000

New member
Aug 19, 2019
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1
Oregon
Looks like you simply didnt have the transmission at enough of an angle for the engine to match up. Glad you figured it out.
That was my thoughts as well. I found a PDF, that looks like it's from GM, about replacing the LB7 and it said to remove the motor mounts.

I appreciate the help, guys.
 

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