47RH Output Shaft Leak

Tobin

Tobin

5.7 IDI Powaa!
94/95 47RH with a NP241DHD behind it. First time I started it up, it leaked between the transmission and transfer case. Pulled the case off and replaced the transmission output shaft seal with a double lipped seal, still leaks. It's a nice steady drip when the truck is running. Friend of mine said he has had the same problem with all the 47RHs and just throw sealer between the two. Is this the answer? case looks good, no cracks that I can see, and the seal fits good on the transfer case input shaft.
 
Is the input on the tcase long enough?. There is a thread on here somewhere where a guy is looking for a long auto input.
 
Did you drive the trans seal in flush or deeper? I pounded one in to deep before and t leaked. Have you slid the seal onto the t case input to check if it's the right size ?
 
I don't know if this is any way related, but I had to change the input yoke on my t case when I went to fat output. Anyway, the new yoke didn't come with the plug in the back of it and I didnt notice it, kept transferring fluid to the t case until it overfilled it and leaked out of about everywhere it could.
 
I didn't know there was a plug in there. Whenever I let a tcase lay input shaft towards the floor they leak.
 
SCHMITTY said:
I didn't know there was a plug in there. Whenever I let a tcase lay input shaft towards the floor they leak.
Click to expand...

There is a plug in the base of the t case input, kinda like a freeze plug. It was missing in a new replacement input to the t case and I didn't catch it.
 
There is also a seal on the front yoke of the transfer case that can leak and push fluid forward.

Another piece of advice. I have had transmissions come in with this same problem, replaced the seals on both transfer case and transmission and it still leaked. Long story short, the idiot who replaced the seal before I worked on the transmission drove the old seal out from the bottom of the seal and gouged the housing whee the seal sits! Needless to say I had to replace the OD housing on the unit. Make sure yours is OK.

I also removed 2 lbs of RTV from this transmission. They could not find the leaks so they sealed it up.
 
odieub said:
Is the input on the tcase long enough?. There is a thread on here somewhere where a guy is looking for a long auto input.
Click to expand...

I'll measure again, but I believe so. I want to say I measured that a year or so ago because I was going to run a clocking ring. I'll double check.

SCHMITTY said:
Did you drive the trans seal in flush or deeper? I pounded one in to deep before and t leaked. Have you slid the seal onto the t case input to check if it's the right size ?
Click to expand...

Nope, right at the edge of the OD housing. It fits the transfer case input shaft perfectly.

jasonc said:
I don't know if this is any way related, but I had to change the input yoke on my t case when I went to fat output. Anyway, the new yoke didn't come with the plug in the back of it and I didnt notice it, kept transferring fluid to the t case until it overfilled it and leaked out of about everywhere it could.
Click to expand...

I'll take a look and see.

It's annoying, I thought I had checked everything. I am almost thinking about swapping transfer cases to something with a fixed yoke on the back, but I can't fit a NP271 so I am not sure what I would run.
 
odieub said:
Is the input on the tcase long enough?. There is a thread on here somewhere where a guy is looking for a long auto input.
Click to expand...

Bingo, the input barely tickles the seal. Now I need to find a longer input shaft. I think this case came out of a manual transmission truck. Makes sense if then. Always something.

Thanks!!!
Tobin
 
Damn I snagged a used dhd off a 24v for a 94 12 valve /47rh dump truck project. I wanted the dhd so I can run a pto for the dump bed. I grabbed the matching drive line yoke. Now I have to go measure my parts.
 
Sure enough the input on the t case is too short. Just measured it with a straight edge and some calipers.
 
For future reference, you will need an adapter to push the seal back so it engages fully on the input shaft of the transfer case. I modified one I had laying around so it is 0.420" thick. Works great.

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