243 input shaft seal

[Reega]

2000 K2500 4l80 243 transfer case:

Changed the fluid in the transfer case and it poured out of the fill hole. So, input shaft seal on transfer case is compromised. Does this also indicate the output shaft seal on the 4l80 is compromised? My searches have not been conclusive….1A auto said transfer case seal, but how is that much fluid exiting the transmission if the output shaft seal is good. I guess I should do both since I’ll have to separate the case anyways, but really more would like to understand the dynamics and failure cause.

 

[DieselTech]

2000 K2500 4l80 243 transfer case:

Changed the fluid in the transfer case and it poured out of the fill hole. So, input shaft seal on transfer case is compromised. Does this also indicate the output shaft seal on the 4l80 is compromised? My searches have not been conclusive….1A auto said transfer case seal, but how is that much fluid exiting the transmission if the output shaft seal is good. I guess I should do both since I’ll have to separate the case anyways, but really more would like to understand the dynamics and failure cause.

Yes do both seals. Replace the transmission output shaft seal & also replace the transfer case input shaft seal.

 

[GoToGuy]

Changed transfer case fluid and it came out the fill hole? That means it's full.

 

[Reega]

Changed transfer case fluid and it came out the fill hole? That means it's full.

Nope, over filled… it poured out. You can’t really over fill from the fill hole

 

[Supercharged111]

I'm with @GoToGuy. The way you described it sounds like there isn't a problem.

 

[Reega]

Sorry fellas, it “poured out”. Essentially, there is no way to get that much fluid in there through the fill hole. You could only fill through the fill hole to the bottom of the hole…it would leak out while trying to fill it. Once I removed the fill plug, it was full force through the hole, above the top. I would estimate a quart or better.

 

[Reega]

Sorry fellas, it “poured out”. Essentially, there is no way to get that much fluid in there through the fill hole. You could only fill through the fill hole to the bottom of the hole…it would leak out while trying to fill it. Once I removed the fill plug, it was full force through the hole, above the top. I would estimate a quart or better.

I guess unless someone filled it on its side?

 

[GoToGuy]

So what you see isn't what your telling us. " Removed fill plug and fluid ran out as was overfilled. " Is not what you said. Words matter.

 

[Reega]

My apologies. My connotation of “poured out” is such that it’s like pouring fluid out of a container. Every time I’ve ever pulled a fiplug from a diff or a transfer case, at most I would get a little trickle of fluid. More often than not, it would be at the proper level slightly below the fill plug. But, yes it was forceful in the exit, indicating an excess of fluid above the top of the fill plug. From what I have researched, this somewhat typical, usually indicating a defective input shaft seal on the transfer case. Most attribute the problem to that. Yet, reason would lend itself to also suspect the output shaft seal on the transmission. I am admittedly naive to the 4l80e, and wasn’t sure if a compromised seal in conjunction with that of the transfer case would cause that volume of fluid to enter the transfer case.