Front Output Shaft Seal Leak after replacement

[Brad M]

I read up on this here on SS, used the TM/34 for info, and replaced a worn front output seal on my M1008 transfer case yesterday after work. I checked the bearing play and there was little to none on the front output shaft. I lubed the inside of the seal, applied a small amount of silicone to the outside diameter of the seal, and gently put it in until it was seated flush. I cleaned the surface of the yoke that the seal rides on then lubricated it. I replaced the yoke and tightened the nut to 120lbs Then I bolted back up the CV/propeller shaft and refilled the fluid and had another leak from the inside diameter of the seal where it touches the yoke. Can anyone give me an idea of what i may be missing or not thinking of that could have caused this seal leak. I have one more seal and will check what failed when pulling it back apart but I am at a loss. Any suggestions or what to look for are greatly appreciated. One I have already heard was to pack the spring side of the seal with grease incase the spring slipped off when the yoke slid in place.

 

[camogriz]

That is a tough one. The only thing I can think of is the possibilty that the inner lip of the seal became inverted upon installation of the yoke or there must be a small tear in the rubber, thereby compromising the seal with the yoke.

 

[Brad M]

Thank you for the reply, all ideas and advice are welcomed. I will be looking at the seal when I pull it back out.

One odd addition was that I drove it to work yesterday and put a bucket under it to catch any fluid that dripped out and there was a trail from where I parked it but the bucket was almost empty. I was worried that I was out of fluid in the t-case. But when I went to top it off it only took two or three pumps from the gallon I had and was full again and then started leaking from the seal so I believe it is only leaking from the part of the seal touching the yoke at the upper most point and once it leaks down past that point it stops leaking. I still plan to change it out with my backup seal but I want to make sure I do not run into the same issue with it.

Thank you again,

 

[Westech]

applied a small amount of silicone to the outside diameter of the seal, .

That is a no no. Seals are to be installed dry. Only thing that goes on it is a little lube on the rubber lip like you did. Adding RTV can distort the seal and make it leak.

 

[Brad M]

That is a no no. Seals are to be installed dry. Only thing that goes on it is a little lube on the rubber lip like you did. Adding RTV can distort the seal and make it leak.

Duly noted and I will not on the next one. I did smooth it out to about 4 mil thick just to aid in putting it in and for a final seal but I will leave it out on the next one.

Do you think it may be what happened with this one?

Thank you,

 

[Westech]

Hard to say... tings to check.. groves in the yoke.... is the end of the yoke leaking and not the seal? cracks in yoke or case.

 

[Brad M]

Hard to say... tings to check.. groves in the yoke.... is the end of the yoke leaking and not the seal? cracks in yoke or case.

I appreciate your advice; yes, this is a hard one. No groves in the yoke. I scotch brited it back to a nice shine where the seal rides and a few cm further. No the nut seal is working fine so no leaks from the end of the yoke. The yoke looks good and I did not see any cracks. Case looked good also. We inspected it closely and wiped all oil out of the space the seal fits and checked for burs before seating the new seal. We gently taped it home with a soft plastic hammer working our way evenly until it was flush all around and then wiped off the silicone that had squished out (no silicone next time). Once done it looked perfect before the yoke went back in place. All I can figure is the spring coming off when the yoke went in. I will check that when we pull it out. This truly is an odd one and again I appreciate the help. The only other conclusion can figure is a defective seal from the factory. It seems like a stretch but I will not know until I break it back down and check. I am hoping to do so this Sunday if my help is not busy. If so, I am on Gen-set repair duty instead.

 

[Westech]

Remember.. (seen this done many times) the spring in the lip of the seal faces the fluid.

 

[DokWatson]

The output seal is probably fine, the yoke has its own o-ring so it doesn't leak fluid around the splines. Most people use RTV under the nut, because a new o-ring is hard to find.

Looks something like this.

 

[Brad M]

The output seal is probably fine, the yoke has its own o-ring so it doesn't leak fluid around the splines. Most people use RTV under the nut, because a new o-ring is hard to find.

Looks something like this.

DockWatson, thanks but it’s not leaking on that end of the yoke.

 

[Brad M]

Remember.. (seen this done many times) the spring in the lip of the seal faces the fluid.

Yep, the seal I used was the newer revision with a slight lop on the outside edge so you knew which way to put it in. the backup I have is the old style without the lip on the outer edge. One was from OD and the other from Saturn can remember which the new revision came from.

 

[Brad M]

UPDATE: Front Output Shaft Seal Leak after replacement

Well it appears the seal may have been the wrong one. At first it looked like I had a newer version with a lip on the outer edge and an original style. I dissected it yesterday evening and the spring was still in place however I noticed what I thought was the newer version had two springs one on the inside and one on the outside of the inner lip. It slipped onto the yoke nicely but was not as snug as the original style one I had. I swapped it out yesterday evening and re-torqued everything and filled it with fluid and there were no leaks. I promptly took it for a mild 4WD run through a nearby construction area and checked it and no leaks after warming everything up. So in hindsight even thought I ordered the front output seal from two locations its always wise to go with OEM and not assume that one is an upgrade. The original style had arrived in a heat sealed package with the NSN info on it and the one that appeared to be a newer type arrived in a folded invoice and was otherwise lose in the box. Thanks for all the advice everyone offered and other than the dissection this time was a third of the time it took to change the first one.

 

[mistaken1]

Who shipped the sealed seal OD or Saturn?

 

[Brad M]

I'm about 90~95% it was Saturn

 

[ratchet196]

Hello

I just bought an 87 M1008 and the front output seal? went out (front driveshaft to transfer case) dripping fluid all over the place.

So now I can't seem to find a seal for it anywhere in this town.

Found the correct seal at napa when they looked up an 82 k 30

Napa 18662