Transfer case output shaft spline sealing.

[mudsharkangler]

Hello.

I have been trying to stop a slow leak coming from the splines of the output shaft/flange on the transfer case of a 1989 M998.

I have replaced the rubber star washer several times, having tried RTV once (per site searches) and also no RTV...both with the same results...a small drip once a week.

Does anybody have any suggestions?

Thanks in advance!

 

[Action]

Hello.

I have been trying to stop a slow leak coming from the splines of the output shaft/flange on the transfer case of a 1989 M998.

I have replaced the rubber star washer several times, having tried RTV once (per site searches) and also no RTV...both with the same results...a small drip once a week.

Does anybody have any suggestions?

Thanks in advance!

Transfer case or differential? If you meant the diff, how tight are you going on the nut?

 

[mudsharkangler]

Thanks. Transfer case output, TM states 110 ft/lbs and that is what i have been torquing it to. Each time I have used a new rubber washer.

 

[AOR]

I did this in my 218 Transfer case a few weeks ago I have probably driven it 30 miles or so and so far not a single drip. Do you know what transfer case model you have? My 218 has a fixed yoke on the rear output if you have this style you should be checking for a groove worn into the yoke itself where the seal contacts the yoke.
If you have a slip yoke style its probably a 242 model and if they are like other NP transfer cases there may be a bushing in there that may be worn out inside of the tail cone. I have seen some yokes throughout the years where fluid actually seeps through the porosity of the metal yoke itself
Where in MD are you located?

 

[mudsharkangler]

It is a 218, I put a new yolk on also. Oil seal on yolk is fine. It is leaking out the spines of the yolk and forming a drop beneath the nut on the front output shaft.

I live near Bel Air.

 

[Action]

Correct me if I am wrong here....

There is no star washer with the output flanges of the transfer case. It has oil seals like the one in the following pic. The star washers are on the diff output flanges.

Do you have the oil seal AND a star washer on that shaft?

 

[AOR]

Is it your front or rear output that is leaking? I got my rear seal and star washer from Kascar for my 218 it fit correctly and I also put Mopar RTV on the splines of the yoke, I also always put thin layer of RTV on the outside of the seals incase there is a nick or scratch in the seal or where it presses into. grease on the outside of the smooth part of the yoke and grease around the spring on the seal to help avoid it from popping out along with red locktite on the nut and torqued to specs.
I do allot of this type of work and learned over the years some extra measures to prevent leaks. I have seen aluminum castings leak through the porosity of the metal as well. You may want to clean it off real good then drive it or just watch and see if maybe the leak is coming from somewhere else.
if its your front output I think there are some cooler lines there as well. I am new to HMMVW's and this is the first transfer case that I have seen with cooler lines running into it.

 

[mudsharkangler]

Underneath that (218 - 110 ft-lb) nut is a rubber washer...which is cut to fit in the splines ( I call it a star washer)...i.e....to seal the splines from fluid leaking up i assume.

I replaced the actual oil seal for the flange (as referenced here) and that is not the issue, it no longer leaks

It is clearly leaking from behind the nut, and just barely a drip a week. It never leaked before I replaced the actual leaking oil seal.

 

[Action]

Is this the washer you are talking about?

 

[mudsharkangler]

Yes, only it is black..maybe more splines on it too.

The blue one is for the differential output i believe.

 

[Action]

I have seen blue and red on the diff.
I can't find any rubber washer on the front or rear output yoke in the 218 parts diagram. Do you have a part number for it?

The only things shown after the oil seal is the yoke, a lock washer, and the nut.

NEVERMIND. the TM is calling the rubber seal a lock washer....

 

[mudsharkangler]

That is correct: 63 5310011865237 86403 4210973 WASHER,LOCK FRONT

It is a rubber washer, like the one you pictured. Odd name for it.

This is it exactly: https://real4wd.com/store/Washer,-Lock-Front-And-Rear-Output

Fits perfectly, but has eventually slightly leaked, all 3 times i tried it, even with RTV.

 

[Skrilex]

That’s odd it won’t seal even gooped. I noticed my t case and trans had an odd red goop that seemed to be semi hardening. Maybe it need to be some non hardening type.