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OK guys. I have had a sprag issue with my XM818 since I picked it up. I had to pull the drive-shaft to bring it home from NC because the sprag was stuck in Reverse.
I have the truck running and driving great now and the only issue holding me up is the dang sprag. I started trouble-shooting the thing about a month ago.
The first thing I tried was disconnecting the air lines from the actuator on the transfer case. I then used an air nozzle and applied air to the lines. It shifted back and forth with a nice "thunk" like it is supposed to. Therefor I figured the problem must be in the valve.
I pulled the tranny access cover off and disconnected the air lines from the valve. I used the air gun and still got a nice "thunk" so I knew the lines between the valve and the t-case were good. I then pulled the valve off of the tranny and tore it down for cleaning and inspection. It was a little crusty inside so I cleaned everything up and re-assembled it. After putting it back on the tranny and re-hooking all of the air lines, it still wasn't shifting the sprag.
Then, I got an extra set of hands from my brother so I could supply air to the valve with the air gun while he shifted between R and 1. It would "thunk" once, but then would stop. I could get the output shaft on the t-case to turn in R right after he shifted and then briefly in 1st after he shifted, but then it would lock up.
If I applied air to the valve with the tranny in 1st, we could hear air coming from within the t-case. My guess is the seals on the piston in the actuator are shot and are moving the piston toward reverse and then the air leaks around and fills the 1st side and locks it into R.
Does that make sense? Have any of you guys had any luck replacing seals on the actuator? Could it be anything else?
Here are some pics from my experiences. Hopefully it might help some of you guys.
Thanks!
I have the truck running and driving great now and the only issue holding me up is the dang sprag. I started trouble-shooting the thing about a month ago.
The first thing I tried was disconnecting the air lines from the actuator on the transfer case. I then used an air nozzle and applied air to the lines. It shifted back and forth with a nice "thunk" like it is supposed to. Therefor I figured the problem must be in the valve.
I pulled the tranny access cover off and disconnected the air lines from the valve. I used the air gun and still got a nice "thunk" so I knew the lines between the valve and the t-case were good. I then pulled the valve off of the tranny and tore it down for cleaning and inspection. It was a little crusty inside so I cleaned everything up and re-assembled it. After putting it back on the tranny and re-hooking all of the air lines, it still wasn't shifting the sprag.
Then, I got an extra set of hands from my brother so I could supply air to the valve with the air gun while he shifted between R and 1. It would "thunk" once, but then would stop. I could get the output shaft on the t-case to turn in R right after he shifted and then briefly in 1st after he shifted, but then it would lock up.
If I applied air to the valve with the tranny in 1st, we could hear air coming from within the t-case. My guess is the seals on the piston in the actuator are shot and are moving the piston toward reverse and then the air leaks around and fills the 1st side and locks it into R.
Does that make sense? Have any of you guys had any luck replacing seals on the actuator? Could it be anything else?
Here are some pics from my experiences. Hopefully it might help some of you guys.
Thanks!
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