Np241

[KallyI]

Back in November, 2005, I posted about my NP241 transfer case being cracked and leaking. BobND suggested: "One cause of transfer case cracking is worn splines on a driveshaft, especially the front one. When the shaft is under load (torque), and the suspension and powertrain mounts flex, the driveshaft splines need to slip in or out to accommodate to movement. If the splines are worn or damaged, and "hang up", case breakage can result."
I believe this is what happened, as it was extremely difficult to get the splines apart.
At any rate, it was leaking for quite a while, and I kept thinking it was the tranny leaking, from one of the cooling lines. One reason I thought that, is the tranny would exhibit signs of being low on fluid, and when it was checked, it would be low. Since the transfer case leak was stopped, there has been no leaks visible and the tranny level has stayed fine, but the question I have is this: If the transfer case was leaking, why would the tranny level drop? There is a seal between the tranny and the transfer case, isn't there:confused:

[Hubert]

On my truck (manual tranny) the manual transmission fluid lubricated the connection to transfer case. There is a seal at the input shaft of the transfercase.

Yours being Auto this fluid would be ATF. On mine the tansfercase lube was also ATF.

Was the crack near the connection? What all was repaired on the transfer case?

[KallyI]

This is a copy and paste from what I posted November 20/05. (for some reason this new BB says I joined yesterday, but I've been in the Forums since October 2003, and checking "The Diesel Page" since 1999):

"KallyI

Contributor
Member # 11265

posted 11-20-2005 04:42 PM
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Has anyone else on the forum had any cracks develop in these Transfer Cases? It is cracked about 2" aft and below of where the 2wd/4wd shifter comes through the case. The crack is about 1 1/2" long. I have no idea how the crack was caused. I have not used the truck as a true 4X4 since August 2000, and I don't run in 4wd mode on dry pavement for any distance. The skid plate protects this area of the Transfer Case fairly well, and I don't recall getting any direct hits under the truck at any rate. At this point, Devcon has been applied to the outside of the crack, and it is no longer leaking, but I am keeping a close eye on it."

There is no visible leaking now, and yes, both the tranny and transfer case have ATF, but it would appear that the seal between the two has failed to the extent that as the transfer case ATF level falls, it is made up from the tranny, thereby depleting the tranny. I guess my next job on the truck is to drop the transfer case and replace the rear tranny seal, unless someone can suggest that this is not really a problem, as long as It's not leaking on either.:D

[Hubert]

" At this point, Devcon has been applied to the outside of the crack, and it is no longer leaking, but I am keeping a close eye on it."

There is no visible leaking now, and yes, both the tranny and transfer case have ATF, but it would appear that the seal between the two has failed to the extent that as the transfer case ATF level falls, it is made up from the tranny, thereby depleting the tranny. I guess my next job on the truck is to drop the transfer case and replace the rear tranny seal, unless someone can suggest that this is not really a problem, as long as It's not leaking on either."

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Did you drop the transfer case? There could be another crack on the face internal to case facing the rear of the auto tranny. Or the visible crack could have propigated internal to the face.

I don't know 100% but would think the transfer cases are the same. I don't think there is a rear seal in the Auto but yes there is a seal on input shaft of the transfer case.

On the manual its splash lubricated and not pressurised lube maybe on Auto's there is enough pressure to add fluid to transfercase if cracked.

You could check level of fluid in transfercase and see if it is overfull. Too much fluid I would think would blow out rear seal of transfercase eventually if you were still adding it?

But if pressure has equalized and no problems drive it and start the savings fund for eventual transfercase replacement ???????????