Sleigher

Okay a while back I noticed a little oil drip from the rear tail-housing (aluminum, original) of my NV4500.
I never really found a crack or problem but after doing a little research I found that this was a potential problem and a cast iron housing was available for a reasonable amount.
Bought the new parts and installed the new tail-housing. The fifth gear nut was solid and in place.
Put it all back together and within a week or so I see oil dripping off of the PTO cover of my transfer case? I did drop it while removing it but the oil that was dripping was gear oil. I put in the AMSOIL that Standard Transmission recommended.
After hoping it was my imagination for a while the leak stopped so I figured I better check the level. It was low.
I bought some new seals and came up with a plan to do the job solo. (see the picture).
Sure enough there was oil in the cavity between the tail-shaft and the transfer case. Probably 6 oz.
I removed the old seal which seemed kinda cheap (less metal than the Timken) but after removal you can't tell if it was bad so I installed the new seal. Standard Transmission had shipped me some gaskets which didn't seem quite right but I'm thinking there shouldn't be oil there anyhow so the seal should do the job. (there wasn't any oil between the two when I disassembled it the first time). So, I slapped it all back together and took it for a short drive to make sure the transfer case shifted proper etc. Now, I'm not sure but I think it is still leaking.
So, has anybody had any experience with these cast iron tail-housings-good or bad?
The leak really pooped all over my pride of removing and installing the transfer case all by my lonesome.
To accomplish this I bolted a milk-crate to my floor jack and then hacked it up some to conform to the t-case. I was able to remove the t-case still attached to my gear splitter without spilling any fluid or dropping it. If I do it again I will make the crate shorter as it was too tall to get out from under the truck and a little wobbly.
Any thoughts on the tail-section will be appreciated. Thanks in advance.

Peter

gorms

Are you leaking gear oil from the tranny through the rear seal? Or are you leaking atf from the transfer case PTO cover?

I had good luck with a timken rear trans seal from Pepboys I think it was. No gasket between trans and transfer case needed-at least I never had one. For PTO covers I use RTV, applied to a CLEAN surface and to threads for bolts for cover.

And FWIW I had better luck without any jacks getting the 'case out, too awkward to balance on a jack. I just let it down easy onto my chest then roll it onto the ground. Then drag it out from under the truck, reverse for installing. I definetly couldn't do that every day though.

I've never seen a cast iron tail before. I cracked the bearing housing on my old 1500 when I lost a cap on a rear driveshaft u joint, vibration killed it. Tail housing was fine.

MikeR

I used the cast iron ext housing for a while on my original NV4500 in my 98, it never leaked. When I had to replace my 4500, I lazily left the iron housing on the 1st trans, and ran the stock aluminum on the replacement trans.
If it keeps leaking I'd think there was a groove worn into the output shaft.

Sleigher

It is leaking gear oil and the only place it can be coming from is the seal, as far as I can tell. There was so much leaking that I thought maybe there was a plug that was missing but I don't see anything.
I drove my truck today and I don't see any leaking yet but the gasket looks moist. I might be low on oil which could be why it isn't leaking or I fixed the problem with the new seal.
I didn't see any groove in the shaft (transfer case), I checked pretty closely and it wasn't leaking at all with the previous, aluminum, tail-housing.

Thanks for the replies any other comments are welcomed and appreciated.

P

Sleigher

I plan on pulling it all apart, again, this weekend.
This time I will remove the tail housing as well and bolt to the transfer case while on the ground. Should be able to see the problem this way.
Sure don't want to pull it apart again.

P

Redlinear

Have you checked the vent on the top of the transmission? If it's stopped up, you'll never get it to stop leaking.

Sleigher

I have not checked that.
This weekend I pulled it all apart again.
I could not find anything wrong with the cast tailpiece. There is a huge difference between the aluminum piece and the cast piece with regard to the sealing face. With the aluminum piece the seal rides at the very end of the TC input shaft. With the cast piece it rides well over an inch forward of the input shaft. Which takes away any likelihood of a "groove" in the TC input shaft. But there was a lot of oil in the cavity, again.
I put it all back together with the aluminum tailpiece. It is now leaking from the original place again. I don't know if it is leaking between the two. I sealed it pretty well.
I'm down to, maybe a crack, above or near the shift bracket or the top plate, which holds the shifter in, is leaking and the fluid is running down the side.
I'm about to drive the truck off a cliff.

Thanks.

P

Redlinear

If it was leaking up high (top plate or shift tower)..It'd be a very slow leak and not really noticable. Just something like a "seep". Doubt you'de get a "drip" out of anything up high.
Seal being installed the correct direction?
Vent tube stopped up and building up pressure?
Overfilling and vent tube puking?
Leaking out of the transfer case instead of the transmission?
Tried an extensive rant of wordy dirds and tool throwing?

Sleigher

If it was leaking up high (top plate or shift tower)..It'd be a very slow leak and not really noticable. Just something like a "seep". Doubt you'de get a "drip" out of anything up high.

I put the aluminum piece back in and it is now a very slow drip. With the cast iron tail piece it puked out a quart in two weeks.

Seal being installed the correct direction?

Yes, I checked, to make sure, when I pulled the aluminum piece out the first time.

Vent tube stopped up and building up pressure?

I don't think it has a vent. I looked around but couldn't fine one.

Overfilling and vent tube puking?

Same as above.

Leaking out of the transfer case instead of the transmission?

Definitely the transmission.

Tried an extensive rant of wordy dirds and tool throwing?

Getting there. Lots of dirty words but refraining from throwing tools. Too tired.

Still need an answer.
Will post more pics.

P

Sleigher

Some Pictures
Here are some shots comparing the aluminum housing to the cast iron housing.
The housings are bolted to the transfer case.
The seal in the aluminum housing rides on a completely different part of the shaft than the seal in the cast housing.
I could not see any problem with the seal or the way it rides on the shaft.

Help.

P

gorms

Vent tube on my 98 is pass. side, next to shifter on top plate. Look for a 90 deg. elbow and a short piece of rubber hose, with breather cap (like axle vent) on end facing forward, real close to floor board. 5 quarts is the normal fill amount.

To each their own, but unless you find a way to break the al. tail I'd forget about the cast piece. Good luck.