Transfer Case Seal

[m-11]

I need to know if National # 6835S is a good replacement for CR 7440. This would be the shift shaft seal.

[MSeriesRebuild]

I can give you the correct seal# when at the shop; however the bigger issue with shift shafts leaking oil is normal wear and rust pitting in the area the oil seal mates with. If the area is not free of pits, grooves, out of round wear, etc., all the new seals on earth will not stop the leaking. We custom make stainless steel replacement shafts, have used them several years now with a great result. We saw so many with rust pits in the seal area, we decided the SS shafts were a good investment. They never rust, thus pitting never occurs. Shaft and seal replacement stops the oil leaking issue for good.

[m-11]

Charles,

I don't know the condition of the transfer case yet because it is still in one piece unlike the rest of the truck. Anyway, I know the transfer case must have been leaking in the past because it is covered with oil and dirt. Also the area under the floor of the cab above where the transfer case sits had a lot of oil and sand. I'm in the process of gathering seals and hopefully that will be all I need. If I need new shift shafts, is that something I can get from you? If so, how much for a pair shipped to 59870? I know there was an engine seal we talked about before but I'll have to look over my notes to see what it was exactly.

Tim

[MSeriesRebuild]

Charles,

I don't know the condition of the transfer case yet because it is still in one piece unlike the rest of the truck. Anyway, I know the transfer case must have been leaking in the past because it is covered with oil and dirt. Also the area under the floor of the cab above where the transfer case sits had a lot of oil and sand. I'm in the process of gathering seals and hopefully that will be all I need. If I need new shift shafts, is that something I can get from you? If so, how much for a pair shipped to 59870? I know there was an engine seal we talked about before but I'll have to look over my notes to see what it was exactly.

Tim

Yes we have stainless shafts in stock, they are custom machined and are $100 each.

What we most often see with a case that is oil soaked like you describe is leaking around every seal and gasket. Most of these cases were built up using no gasket sealer, so they were a cinch to seep and leak all over more than anywhere else. I doubt if you stop it doing anything short of total disassembly, cleaning, and build back up using new gaskets with a correct sealer and thread sealant. At that point, you may as well rebuild it totally and be done with it.