Changing gasket on tail housing

clhman

clhman

Member
I dropped my trans and transfer case because they are both leaking. I got a new pan gasket for the trans but the tail housing gasket is leaking as well. Is that hard to separate? Do I have to dissamble the whole transmission to change that gasket? Any help would be appreciated. Thanks.
 
Assuming you are working the vehicle in your signature:

it's been a few years since I worked on a Scout, but from my memory....
The tf727 in the Scout II is a 'married' unit to the transfer case.

You will need to separate the two and the adaptor, the flange with 5 bolts in a texas bolt pattern at the Dana 20 tc. Then remove the big nut & drive gear. Then the extension housing can be unbolted and come off for a new gasket. You should replace the shaft seals that are in there as well as the gasket for the tc mating surface.
 
Oh okay. I'll try that. I was afraid to get too far into it if I didn't know what I was doing. Another thing, the nut that holds on that gear was loose. I assume it should be tight? It looks like a castle nut but there are no holes in the shaft. What should I tighten it to?
 
Really tight...175 ft/lbs. It isn't a castle nut. It is a bit odd-shaped though for a reason and that is to prevent backing off when properly torqued. They can lose their effectiveness in that regard after numerous torque cycles. Also replace the gasket between the t-case and the adapter housing if it is compromised in any way. Resist the urge (if you have one) to use silicone based rtv in place of or in addition to these gaskets. Rtv has its place and purpose, though it escapes me at the moment. The gasket between the t-case and housing serves as a very thin spacer shim, which cannot be duplicated with any smeared on goop.
While you have the trans out and the pan off, it would really behoove you to adjust the bands. The low/reverse, or rear band adjustment screw can only be accessed while the pan is removed. You need an inch/pound torque wrench, or a ft/lbs wrench that can be adjusted down to 6 ft/lbs, which is 72 in/lbs., the initial torque setting for both band screws. Then each is backed off the appropriate number of turns from there and locked down, which for an unmodified 727 behind an sv8 is 2.25 turns out for both. An 8-point 5/16" socket is also very helpful for accomplishing this task, as the adjustment screws have square heads.
 
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175ft/lb? That's crazy tight! I'll do it if that's what's necessary. I'll mess with the bands too at the same time. Thanks for the advice.
 
Yessir. That's shtrate outta the fsm. Might explain why you found it loose. Someone ahead of you probly thought fitty ft/lbs was good enough for gummint work.:nono: it's easier to do when the trans is attached to the engine. Or if you've got a solid work bench you can anchor it too with a ratchet strap, that works too.
 
I bear-hugged it, my buddy was on the torque wrench and we ratchet strapped it. It's tight now. Trust me. Going to reinstall tomorrow. Stand by.
 
Got it back in late last night. Lots more crap to do. Hopefully it doesn't leak when I fill it back up with fluid. It looked like it had been leaking for most of its 33 year existence.
 
Okay. Lots of stuff done but I have a few more questions...I got my fsm but some things don't make sense to me.

1. There is what appears to be a temp sending unit on the passenger side towards the front of the unit. What is that and what does it do? Couldn't find an answer in the fsm.

2. Adjusting the bands. So the manual says to torque them to spec - then back them off...? Am I just being dense on this? Wouldn't that just undo what you just did...?!

Sorry if these are stupid questions.
 
There are three pressure test port locations on the passenger side of the trans case which are normally plugged with small bolts. Some folks opt to install an aftermarket atf temp gauge for additional monitoring, which isn't a bad idea. This requires installing the thread in temp sensor into one of the test ports.

The reason for torquing the band adjustment screws is to establish a uniform starting point for the specified number of turns to back the screw off. A little different principle than is normally associated with torquing fasteners, as usually once the torque setting has been reached, the job is done. In the case of the auto trans bands, the amount of turns backed off is the finishing point, rather than the torqued value.
 
Okay. I understand the torquing now. I'll try it tonight.

With the temp sensor though, it's plugged into a factory harness...? I can take a pic when I get working on it later tonight.
 
Well, that could be one of those funky 1980 things. I think maybe I've heard of this before. Possibly some emissions mumbo-jumbo. No Scout was equipped with a atf temp gauge from the factory.
 
Here's the sending unit in question. Thoughts? Do I plug it with a bolt? Do I connect it back the way it was? The wire is in rough shape so I'd have to redo it anyway. Any idea of what it is would be appreciated.
 

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Also there was nothing in the 2 threaded holes in the sides of the tranmission were the torque converter goes. Do I plug those or leave them open? They are threaded.
 
clhman said:
here's the sending unit in question. Thoughts? Do I plug it with a bolt? Do I connect it back the way it was? The wire is in rough shape so I'd have to redo it anyway. Any idea of what it is would be appreciated.
Click to expand...

I have a vague recollection of some individual more in the know schooling me about that item. I can't remember if that was here or bp. I also can't remember precisely what its purpose is. I don't know if that's a 1980 only deal or if it came into play a couple years earlier. I don't have access to the later sii service manuals. My junk is all pre- '75. I know it is emissions related and I know the overwhelming majority of IH vehicles equipped with 727 autos did not have that sensor installed. Unless you are going for 100% original function, I wouldn't lose much sleep about redoing that wire. No need to remove the sensor in favor of a small bolt unless the looks of the sensor bother you. It is plugging the hole just fine. If you get froggy at some future date and want to know how hot your atf is while operating, you can buy a gauge kit and install the included sensor in that location.

update...I did a little searching and this topic has come up elsewhere, probably more than once. That sensor is a fluid pressure sensor that works in conjunction with a coolant temp sensor on the rear of your passenger side cylinder head. There are varying degrees of fluid pressure present at that location when the rig is in a forward gear. This was all part of the kalifornicate emissions shizz. Those sensors can develop a leak in rare cases, so you May want to preemptively install a plug bolt there on second thought. Also, the rear test port location is better place to install an electric temp sensor into.

clhman said:
also there was nothing in the 2 threaded holes in the sides of the tranmission were the torque converter goes. Do I plug those or leave them open? They are threaded.
Click to expand...

If the holes you're referring to are large diameter with one on either side of the case, those are cross-member mounting holes that don't apply to your Scout. The IH version 727 case was cast with provisions to be installed in multiple vehicle platforms. Those forward holes are for installation in a full-size pick-all rig which utilizes a completely different cross-member mount setup than the scouts. They can be left vacant in your case.
 
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Thanks for the research and the great info. I'll probably remove it and plug it. My goal with this project is simplicity. I am removing everything that isn't essential. All extra wiring, emission stuff and cruise control have been removed. I think I found the other sensor that you're referring to. It is at the top of the block at the very back on the passenger side. It was unplugged. I only noticed it when I was on my back installing the tranny. That must be the one sensor in question. If that's the case I'll remove it and plug it also. Thanks again for the info.
 
Okay so I'm an idiot. The transmission went back in fine and isn't leaking. I'm still adjusting the kickdown, but that should be fixed soon. My problem is with the Dana 300. I know this is the transmission forum but this is my tread so I might as well continue it here.

When dissassembling the transfer case, I got the shims mixed up. I couldn't remember which shims went to which output shaft. The moral of the story is now everything is fine and it doesn't leak except the tail shaft is tight. Not cool. I have a total of 3 shims. I've tried 0,1,2 and 3 shims on that shaft all to no avail. I've even switched the yokes. I have pulled that stupid yoke off with a puller a dozen times. What am I doing wrong? Do I add more shims? What is making it tight? I'm stumped and ready to haul the stupid gearbox to a shop and ask them to un@#$% whatever I did.:confused:
 
Sorry bud. I'm not well versed in the t-cases. All I can do is refer you to the appropriate section of a service manual and/or exploded view diagrams of d300's on the webs. They are much more common in Jeep vehicles. The input configuration differs somewhat, but that doesn't influence setting up the output end play.
 
Thanks. I went by a specialist shop and it sounds like I need to take the whole thing out and take it back apart.:mad2: I mixed up the shims somewhere. Bummer.

My next question is I bought a pan gasket and filter for my 727from IH parts and while I was messing with the t case I noticed that it is leaking bad. It is the thick rubber one. I didn't use any gasket sealer. Should I have or maybe I got it crimped somewhere?
 
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