Transfer Case won’t Stay in 4WD

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
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Crux444
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Location: Burlington, ON, Canada

Transfer Case won’t Stay in 4WD

Post by Crux444 » Thu Sep 01, 2022 7:51 am

I recently identified that my M151A2 won’t go into 4WD. I can push the transfer shift lever forward to engage the front wheels, but as soon as I start to drive, it pops the lever back to 2WD.

The transmission and transfer case were stripped and rebuilt over the winter; no issues with the gearing was noticed.

Could it be that the transfer gears aren’t correctly aligned with those on the output shaft? If so, is there a nifty hack to align them, or do I have to pull the power oack and transmission and do it all again?

Thanks as always,
Sean
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)


Rickf
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Re: Transfer Case won’t Stay in 4WD

Post by Rickf » Thu Sep 01, 2022 8:46 am

Did it do this before the rebuild?
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

Crux444
G-Staff Sergeant
G-Staff Sergeant
Posts: 51
Joined: Tue Mar 23, 2021 4:15 am
Location: Burlington, ON, Canada

Re: Transfer Case won’t Stay in 4WD

Post by Crux444 » Thu Sep 01, 2022 10:39 am

It did not. Hence why I think it may be a gear mesh issue
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)

lpcoating
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Re: Transfer Case won’t Stay in 4WD

Post by lpcoating » Thu Sep 01, 2022 2:47 pm

Do you put the spring and/or circlips back on the selector shaft? The ball detent and spring?

Rickf
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Posts: 5911
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Location: Pemberton, New Jersey

Re: Transfer Case won’t Stay in 4WD

Post by Rickf » Thu Sep 01, 2022 3:26 pm

I am thinking the same as Guy, it sounds like it is not being pushed all the way into gear. Possibly a circlip not installed or not all the way and fell off. If this is the case you might be able to fix it through the side cover on the transfer case.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

lpcoating
Sergeant Major of the Gee
Sergeant Major of the Gee
Posts: 384
Joined: Tue Apr 17, 2012 6:32 pm
Location:

Re: Transfer Case won’t Stay in 4WD

Post by lpcoating » Thu Sep 01, 2022 5:14 pm

It is possible to pull cover and install circlips with power pack in the truck but it isn't fun. Get ready to let the f bomb fly!

Crux444
G-Staff Sergeant
G-Staff Sergeant
Posts: 51
Joined: Tue Mar 23, 2021 4:15 am
Location: Burlington, ON, Canada

Re: Transfer Case won’t Stay in 4WD

Post by Crux444 » Fri Sep 02, 2022 8:43 am

Thanks for the insight. I’ll review the manual to gauge the amount if work involved. The jeep is a pavement princess, so 4WD isn’t an immediate requirement. Sounds like something to keep me out of trouble over the long Ianuary-February 2023 nights!
Canadian Army (1988-2011)
Kandahar, Afghanistan 2006-2007

M151A2 CDN (1974)


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