Author Topic: HELP! Leaking Final Drive  (Read 366 times)

Offline bcroe

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Re: HELP! Leaking Final Drive
« Reply #20 on: January 08, 2018, 09:19:43 AM »
The original gasket is 2 layers and one of the gaskets has a slot in it that is the vent.   If the last person just sealed it with sillycone its not vented so when it gets hot it just looks for any place to escape it can find.

I forgot about that.  Someone told me they could be vented by a small
hole at the top of a side output shaft seal instead.  Bruce Roe

Offline TJ Hopland

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Re: HELP! Leaking Final Drive
« Reply #21 on: January 08, 2018, 04:51:10 PM »
There is a hole in one of the seals too, I forget which side but I was thinking that was more related to some function of the seal than venting the whole case.    I should go look, somewhere I have a set of seals and gaskets I bought 20 years ago but never needed.   

I remember that hole in the seal, it was an oversized over priced unit and I think there was a note in the box that said to pay attention to its position when you install it.    What I remember about the gasket is its a typical thickness cardboard like thing with the notch in the top and the second layer complete one is just like paper.  Seemed like an odd design but it seemed to work. 

How did the downsized version vent?   I have never done anything but add oil to one of those.   I can picture something I own with a hose attached but I may be thinking of a truck. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline The Tassie Devil(le)

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Re: HELP! Leaking Final Drive
« Reply #22 on: January 08, 2018, 06:25:08 PM »
The original question was about the seals, and the cover gasket, which is a one piece gasket.

When did he say that the Trans to third member gasket/s were leaking?

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline bcroe

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HELP! Leaking Final Drive
« Reply #23 on: January 08, 2018, 07:15:30 PM »
Quote from: The Tassie Devil(le)
The original question was about the seals, and the cover gasket, which is a one piece gasket.

When did he say that the Trans to third member gasket/s were leaking?
Bruce.

I didn't remember a suggestion that the trans to final drive was leaking.  I would not
expect it to leak if properly assembled (let me tell you another story).  That special
vented gasket is for the final drive gear cover.  Don't remember how the 79-85 vented. 
I had 2 79 final drives fail because of bad manufacturing.  A few teeth would just break
off and jam with no warning.  One of the reasons I converted the 79 Eldo to a Gen II
TH425 trans and final drive.  Bruce Roe

Offline TJ Hopland

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Re: HELP! Leaking Final Drive
« Reply #24 on: January 08, 2018, 08:42:20 PM »
I didn't think we were ever talking about the gasket between the trans and final drive.  Were we and I missed it?   I remember that being a flat gasket and there were seals on both the trans output shaft and final drive pretty much identical setup to a 4x4 transfer case.   Those seals go out you end up with fluid mixing which can be a puzzling mess till you figure it out. 

The cover gaskets I have dealt with were two layers, there is a paper one that is pretty thin and then a thicker one that has a notch at the top.  IIRC there is a tab that sticks out on both pieces that has a staple in them to hold them together during assembly.  Once assembled you can cut the tab and staple off.  I sort of remember instructions on the package or a sheet of paper in the box saying to make sure you don't reverse the order and to remove the staple only after its installed and torqued and that you had to make sure some hole or passage wasn't blocked.    I'm pretty sure what I had and still have somewhere was a fel pro set.   If I remember I will look around the shop tomorrow and see if I can find it.  Maybe it depended on the year?  I wonder if there were venting issues with those and the made some changes over the years?    A quick search shows some with the holes and some without, none that I saw show both sides, one does look like its got a staple in one of the tabs.   Maybe this is part of his issue?  They changed the venting around so you could end up with no vents if you don't do your research?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Offline The Tassie Devil(le)

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Re: HELP! Leaking Final Drive
« Reply #25 on: January 08, 2018, 09:08:14 PM »
When I pulled the cover off my own third member, I do not recall seeing two gaskets.   Just one, which was leaking.

I do remember the reference to two gaskets, and a vent, being mentioned in the Shop Manual, but could never find a replacement anywhere, and even though the shop manual describes it, I didn't know what to use to replicate it, or which position the vent was.

The Shop Manual also shows the axle seals with vent holes in them, at the top, so I was wondering, with these in place, why would there be a need for another vent in the cover seal.

My own car is running well with silicone at the cover, and I haven't had to separate the third member from the Trans as it isn't leaking there.

Anyone with a picture of both gaskets?

Thanks,

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline danjarrett1

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Re: HELP! Leaking Final Drive
« Reply #26 on: January 08, 2018, 09:27:51 PM »
The car only has 61k on it, I did find a replacement gasket from Maher on Amazon, came in today. It looks like a good quality gasket. Will post a pic tomorrow of the gasket and packaging in case anyone else might be looking for one
1974 Cadillac Eldorado convertible
2007 Cadillac Escalade
1980 Cadillac Seville “Bustleback”

Offline The Tassie Devil(le)

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Re: HELP! Leaking Final Drive
« Reply #27 on: January 09, 2018, 12:29:07 AM »
Thank you.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Offline danjarrett1

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Re: HELP! Leaking Final Drive
« Reply #28 on: January 09, 2018, 10:24:38 PM »
Said I would post pics of the gasket I found, here it is:
1974 Cadillac Eldorado convertible
2007 Cadillac Escalade
1980 Cadillac Seville “Bustleback”

Offline The Tassie Devil(le)

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Re: HELP! Leaking Final Drive
« Reply #29 on: January 09, 2018, 10:30:38 PM »
Is this a two piece gasket as described in the Shop Manual?

Is a vent supplied to attach to protect ingress of outside contaminants to the diff?

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)