DUKW Transfer Case Leaking

[renovate7]

I'm leaking oil out of the lower shaft that powers the middle axle. I found a cross for the original seal number and have ordered one thru NAPA. The OE number is 3659542 and the NAPA number is 19970. Can anyone tell me if I'll be able to disconnect the drive shaft and replace this seal without pulling the TC? And if I have to pull it, how much does it weigh? I don't have access to an overhead lift so it could be interesting.

[Steve Greenberg]

Hello,
You may be able to replace the seal with the transfercase in place. There is not a lot of room down there. Your probably going to have to pull the transfercase in order to replace the seal. Make sure your yoke is not worn down or your new seal will do you no good. You may have to get a speedy sleeve for the yoke. The transfercase weighs around 200 lbs.
Good Luck,
Steve

[Gordon_M]

I'm not sure myself, generally these things are not easy to move unless the case is out and on the bench.

Have a look at the fill level plug, and look at any shafts that run below this level in the case - where the seals are under oil all the time. As a minimum, if you have the case out, you should replace all the seals below that level, and preferably all of them. Speedi-Sleeve on all worn yoke surfaces.

In your position I'd get another transfer case, doesn't have to be a usable one. Stick it on the bench, pull all the yokes and sleeve as required. Then you can either just swap that case in, or use the seals, yokes and sleeves to populate your original T-case, after a careful check of all the bearings.

Most DUKW owners benefit by having at least a spare engine, transfer case, differential, and pillow block on the shelf ready to go if required. Swap in rather than fix in place for major items. If you can't find the DUKW-specific ones, just get ordinary CCKW units, preferably banjo axle, then you can swap the DUKW stuff like pillow block end yokes when you need to.

[W. Winget]

Let me start with I have two dead DUKWs so I'm not into the maintenance that deep yet...
That said, what's the TM call for when the transfer case has a leak? It will (should) list the step by step for the process to either do it in place or remove it. (some TMs were on-line with the USCG reports for download)

2nd, a pair of 4x4's laid atop each other across the beam of the rear cargo area (forward part) should allow you to lift out the transfer case with a comealong or chainhoist ($40 at Harbor Freight) to a position where you could sit in the DUKW and work on it (can't recall if the cargo separator panel is right above it or behind it without uncovering Dead DUKW II).

Point is, if it could be done without removal I'm sure the Army put it in the TM, if not they likely used another DUKW to pull the dead DUKW guts out.
Good luck with it, Dead DUKW I, has a broken off front TC Yoke where they must have ran the girl across a log?, cracking the transmission housing as the gear climbed out of it's housing and finally snapping the shaft clean off the front of the transfer. Hence my purchase of Dead DUKW II that needs hull work.
V/R W. Winget

[Gerben Faber]

You can do it leaving the TC in place. Unbolt the shaft that goes to the middle axle and drop it down, remove the nut and the flance from the splined shaft that sticks out of the TC.
If there is not enough room for you, lift the rear axle far up so the middle axle pulls back from the hull and then the shaft will pull back with it.

The seal sits in a flance that it bolted to the TC with 4 bolts. Get them out, replace the seal in the flance with a new one on your workbench and get everything back in place. Shoudn't take more than one hour. It's a little bid difficult turning wrenches with your head down and your feet up.

Here's a link to a picture of a cracked TC to give you an idea how the flance with the seal sits: http://www.pirate4x4.com/forum/general- ... dawgs.html

Succes, Gerben

[motto]

, Dead DUKW I, has a broken off front TC Yoke where they must have ran the girl across a log?, cracking the transmission housing as the gear climbed out of it's housing and finally snapping the shaft clean off the front of the transfer. Hence my purchase of Dead DUKW II that needs hull work.
V/R W. Winget

Wow! I find it hard to imagine that kind of damage. I'd sure like to see some photos if that was possible. I would have thought it impossible to inflict external damage to a DUKW T/Fer Case short of hitting it with artillery fire.

David

[Gordon_M]

Wow! I find it hard to imagine that kind of damage. I'd sure like to see some photos if that was possible. I would have thought it impossible to inflict external damage to a DUKW T/Fer Case short of hitting it with artillery fire. David

A DUKW drivetrain is a fine thing, but it has its weaknesses, remember it is a standard 2.5 ton truck drivetrain so put it in a heavily loaded DUKW and it is well up to its design limits. You can't kill a GMC 270 with a big stick, and that goes for the five speed box too. The weakness seems to be in the relationship between the transfer case and the rear axles. Either the intermediate differential goes west and takes out the transfer case, or vice versa. Just every now and again the pillow block ties itself in a knot and wrecks that bit of the drivetrain too. People insist on re-engining DUKWs with big turbo diesels, but all that does is tear up the drivetrain faster. If you have to re-engine, use a smallish diesel with just a little more horsepower than the 270.

The solution is constant maintenance and checking. Lube the heck out of everything, check the pillow block for play every time you are under it, and gather up spare parts, as I mentioned earlier.

There is another odd fact about the transfer case, but this one just hurts your ears. A brand new transfer case can scream like a demon every day but work for years without complaint, a quiet one can break any time it feels like it. The noise output isn't helped by being just an inch from a reflective metal sheet either.

Constant by-the-book maintenance, constant check and lube, read all the manuals, and when you get to the end - read them again. It is a wonderful vehicle, but only when properly maintained.

[renovate7]

Thanks for the replies, they are greatly appreciated. TM9-802, pg 298, only gives instructions on removing and reinstalling the TC. There is nothing about servicing it in place. Gerben I like the idea of lifting the rear axle to get the center axle to drop down taking the drive shaft with it. I've spent MANY an hour in this hull working on everything imaginable. As it sits I think it would be very close as to whether just disconnecting the universal joint and letting the shaft drop would provide enough room to work. W. Winget I also like the idea of using 4x4's to lift it enough to hopefully get clear access to it. It is bolted to a big cross member. Might also be able to lift it enough to tilt it and get each end exposed enough to work on. I ordered a complete kit from Vehicles of Victory primarily to get the gaskets. As I understand it the seals will be old NOS and leather. I would rather use a newly made seal. Can anyone tell me how to get a correct speedy sleeve? I have an excellent NAPA in the area. Would they be able to help me if I took the yoke in? We have a part number for the new seal to help...I'm pretty OCD about maintaining this. I have many hours in restoring it and don't think there are too many bolts or screws I haven't turned...I'll post how I come out on this, hopefully with pictures...

[johne504]

I have had my transfer case out a couple times. Its pretty easy actually. Hardest part is pulling the bulkhead, but after than its pretty simple. Leave the crossmember on the T case, and disconnect all three drivelines and linkage. You will need a overhead lift of some sort, because it is heavy.