M818 front axle not engaging

[tommygun]

I recently picked up a M818 from Redstone Arsenal (euc cleared in 9 days ) everythings works but front axle wont engage. Here is what I have tried so far
1. Checked operation of poppet valves on side of transmission ,air comes from front valve in reverse , rear valve when taken out of reverse
2. Checked that air was going through lines to actuator on front of transfer case
3. removed actuator , cleaned and honed , cleaned and lubed piston
4. Checked movement of piston/shift fork , slids freely in and out ,there is no loud thunk when moved
5. Jacked front wheel up , had wheel rotated while moving piston in and out , no difference , could hear some clicking noise from transfer case
6. reassembled , getting air released correctly when shifting into and out of reverse
7. Jacked front wheel up , put in reverse wheel turns both directions ,same in first gear
8. Drove truck up slippery hill no 6x6 in forward gears , but sometimes works in reverse
Any help would be greatly appreciated Thanks

 

[BKubu]

Bad sprag. About $300 and a day's worth of labor. John Winslow, a long time dealer, tells me that about one in three M809 5 tons has a bad sprag...at least according to the ones he buys.

 

[tommygun]

Does the transfer case have to be removed from truck , or can sprag be replaced by removing the front housing with it still in truck? Is there any special tools or knowledge needed to replace sprag ?

 

[MilitaryRestoration]

if you're good you can do it with out removing it... I've seen it done. And yes it does sound like the sprag

 

[BKubu]

Agreed...Winslow replaces them with the t-case still in the truck. Not a fun job from what he tells me.

 

[jwaller]

it seems that ppl rolling nackwards while not in R or vise versa takes it's toll.

 

[m139h2otruck]

Before you pull the case or try to fix while in truck, it would be a cheap fix to try and flush the case once or twice and refill with new gear oil. If you look at the TM on these, the rollers can stick in the "off" location in the sprag case and not engage the output shaft. Just go easy, not too far or fast, when you fill the case with fuel/ATF for the flush.

 

[tommygun]

Thanks , do you happen to know the TM# . I will try the flush and refill before taking the trasfer case apart