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1991 205 "weirdness"

dyeager535

dyeager535

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Went to replace the rear output shaft housing (for lack of the correct term) gasket last night, and noticed while scraping all the crud off the cast iron piece, that there is a hole in it.

I don't think the design has ever changed TOO much over the years, but basically, there is the transfer case body, then this cast iron piece that in my case is where the VSS mounts, then a cast aluminum piece that holds the seal for the yoke.

The hole is obviously there from when it was built, and intentional. It's about 1/4" diameter, opposite the VSS (so it points kind of towards the driver, up and to that side) and is open to the inside of the case. I blew on it, and there was no restriction. I assume that it is either a vent, or missing a rubber(plastic?) plug like on top, above the shift rails. It's not threaded.

Anyone else know about this hole? The gasket/seal kit I bought didn't come with ANY plugs, so no clue if it's a vent that is supposed to be open (can't imagine that) or if it DID have a plug and that came out somehow.
 
Is there any other vent thingy on the case? I'll look at mine at lunch and see if I have it too.
 
dhdescender said:
The hole is an oiling port, it's on the front of the case aswell. It allows the bearing to be fully surrounded with gear oil.
Click to expand...
I think he's saying this hole is visible externally.
 
Yeah, it "vents" the innards of the case to the outside air, sorry I didn't make that clearer.

As long as the case doesn't have a bunch of dirt on it, you MIGHT be able to see it if in the truck, but more likely you'd have to feel for it.

No other vents on the case, I've not looked at an older 205 to see if it is setup the same way.

I didn't disassemble the housing pieces (reluctor ring, bearings inside) but from the little bit I could see, it looks like there is a cast in "baffle" (kind of like inside a valve cover for the PCV/breather) that might prevent oil from being slung out the hole, but still doesn't seem right to have it vent to atmosphere like that...I would think you would end up with rusty gears with prolonged sitting, and at worse, full of water from fording something deep.

This 205 came from a truck that I suspect was driven off a cliff into a river (there were crayfish in the broken radiator hoses for instance) but the t-case fluid was not contaminated by water, and if there was a plug, I don't think we dislodged it removing the case from the truck.
 
IIRC it is a little press in vent.
Prolly removed previously so that the bolt in front of it could be removed from the rear bearing housing.
That's where mine is.
Ya could tap it for a 1/8 npt and use a 1/8 fitting with a hose nipple on it.
 
Look at the rear output shaft/bearing housing.
Starting from the bolt over the fill plug go clockwise to the 5th bolt, about the 11 oclock position.
It is right in front of it, with the breather in place ya have to remove all bolts and leave that one for last, back it out till it hits the breather and pull the housing out a bit, back out bolt and repeat.
Same for going back in.
Unless ya remove the breather so you can just remove the bolt.
But then most see it is a press in fitting and just plug it or leave it open after mangling it getting it out.
 
Any idea when they went to this compared to earlier ones? What other ways have they been vented? I had my front diff vent plug up this year, and even without fording, it was pushing fluid past the diff cover seal. Tapping was my other idea.

Anyways, for a pic, this is all I have
205 diagram I don't see a vent, nor do I see anything referencing that hole. But basically, the rib near where #62 is pointing, (the rib running front to back) is very close to where the hole is.

Of course, there are also two rubber plugs over the shifter rails, which aren't listed in that diagram either. I doubt that changed '85-86 to '91.
 
I would just plug the hole, the t-case will vent through the gearbox as they are not sealed units.
I went through the hassel of not removing mine and was starting to route a vent line when I realized that I could have removed it and just put a plug in it.
I capped mine off with a vaccume cap.

A divorced 205 would need a vent as it is totaly sealed and would eventualy start to puke lube from the seals if not vented.

BTW the married 205 Ford unit I robbed parts from did not have a vent hole in it.
 
How do you mean not sealed? I know a lip seal isn't going to keep pressure back, but I know it will push fluid past if there is. Isn't a divorced setup "sealed" the same way, a lip seal on the input shaft?

Besides, there is a seal on the tranny output as well, which means anything that gets into the adapter will sit there, pooling up.

My 465/205 adapter seals are bad now, and it pushes fluid into the case, once the case fills, it spews fluid out of the front and rear output seals.

I dunno. Guess I'm kind of picky about stuff like this, but GM wouldn't have gone to the expense if they didn't think it necessary, at least thats my reasoning.

Just wonder why they decided it was necessary if Ford (or even earlier GM's?) didn't.
 
When I had my 205 apart there was no seal on the input shaft of the t-case and no seal on the output shaft on the tranny. Just the adapter with the gasgets and the coupler. (1980 old figure 8 style). Nothing that I could see that would stop fluid tranfer from one to the other. And as the passage in the adapter is quite higher than the fill plugs on both you would have to overfill the the gearbox quite abit to get the leval to a point where it would start to tranfer fluid to the t-case.

So by looking at the way my 465/205 is set up they essentialy become one big sealed unit and vent through the gearbox.

Looking at that link you posted it looks like there is an input shaft bearing retainer, or is that the adapter(item 75). Is item 73 the seal?
If that is the case then the t-case would need to be vented.

The Ford case I took was a 1978 attached to a 435 with the same kind of fig 8 adapter that I have, the coupler looked to be a 32 spline but other than that it appeared to be the same design as mine.
 
Yeah, there is an input shaft seal. Even on the 465/205 setup there is a seal, because if there isn't (like mine with the failed seal) the transmission fluid ALWAYS ends up in the t-case, and it fills the case up to the top. At least the bottom of my truck is protected from rust for awhile.

I guess on a 4L80E/205 setup swapping fluid wouldn't be that big a deal, but I'm sure it would do the same thing my 465/205 is doing if a seal fails.

75 is the bearing retainer, 73 is the seal.

Just an FYI, you can look at the part listing(s) here
 
Thanx for the link.

After looking at an older style parts breakdown there is the input bearing and snapring then an o-ring and snapring.
It would appear that my case is missing the o-ring. :blush:
Oh well it has ran that way for years and hasn't had a problem.
I think I will go ahead and reopen the vent all the same, route it into the rear diff vent like I had planned.

It is possible that the Ford case had a vent hole and it was covered over with crud, I never did clean the rear housing that well as I was just after the front and rear outputs.
I know where another case just like it is at, I'll check it out the next time I am there and see if that one is vented just for S&G's.
 
I took some pictures for others that are curious, I just can't upload them now.

The old case I have (70's I suspect) DOES have a metal vent, but its at 12 o'clock.

Now you mentioned something about messing them up...are they just a press fit, or are they like a rivet or something?
 
They are just a straight, press fit hose fitting.
Prolly not availible, I looked for one for my front diff and wound up drilling and tapping it.
 
Yes, I find it surprising that the part is obviously there, as are those two plugs on top, above the shift rails, but they aren't listed in the parts break down. They will list bolts you can get at any hardware store, but not the things you can't find. :crazy:
 
Those two plugs are just rubber balls and usualy wind up getting the 1/8npt plug treatment.
Somehow both of them vanished when I had mine apart.
Of course being in peices on the bench for 6 months don't help LOL
I didn't even try to find em, I just cut threads and used a 1/8npt plug to seal em.
 
The seals aren't in the case, they're in the adapter, Ron, that may be why you missed them.

I'd honestly state that nearly nobody ever replaces them, me included. Since I have books and part numbers now, the next time mine is apart those seals are getting replaced.:grin:
 
http://dyeager535.topcities.com/205/index.htm

Well I think everyone understands what vent I'm talking about, but in any case, I was just now finally able to load up the pictures.

http://dyeager535.topcities.com/205/index.htm

I went to put the input shaft seal in the other night, wouldn't you know, the kit I bought doesn't have the right seal! But, it did have two that were the right size, but only single lip. I just pressed them in place back to front. Hopefully that works, I don't see why not, but we'll see.
 
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