I have a 1974 Eldorado convertible, affectionately known as “CADZILLA†I bought the car a few months ago expecting a few repairs, and so far, everything I’ve found has not been that much of a surprise. I am struggling with one issue that I cannot find any documentation on. I bought the GM 74’ Service manual, ( it’s a well written manual in my opinion) but there’s very little about the final drive. I have a fair amount of leakage around the whole pumpkin, it may be that the output shaft seals are leaking but it’s hard to know exactly where the leak is because the differential cover is leaking. Here's the dilemma, the previous owner gobbled a ton of sealant on it but I'm not sure that it's right, does anyone know if there is an applicable gasket for the cover or is it sealed only with silicone sealant?
The cover can be sealed with a Silicone, if you don't have a gasket, as there is supposed to be a gasket there. I use Loctite 5900 silicone, as this stuff is also compatible with Auto Trans fluid.
The side seals are replaceable, but one must remove the axles to gain sufficient room to access these.
Bruce. >:D
Thanks for the reply, I intended to try to locate a gasket or maybe even a part number from a diagram for a gasket....using correct silicon formed gasket is an option, and in the end, will likely be the solution. Just wondering if anyone I. The Eldo word knows if there was a gasket there when this thing left Detroit!
Yes, there was a gasket.
Bruce. >:D
What is the gasket refered to? The only gasket that I can find is the replacement gasket between the final drive and the transmission! I cannot find a reference to a differential cover gasket. Anyone have any idea where to find one? OPGI doesn’t t recognize it, neither does Caddy Daddy. Any other resources I should check??
I too could never find a replacement, but the Shop Manual refers to one as a Seal Cover Gasket.
Plus, the Shop Manual makes note of sending the Third Member back to the Dealer for the Factory to service it. The internals are not designed to be rebuilt by outside shops.
Bruce. >:D
It's called a Final Drive Cover gasket. Group # 5.399 Part # 231285 in the MPL. Might be available GM or try NAPA.
Bob
fel pro seems to have a lot of stuff,, gaskets etc,, funny i needed a oil pump gasket, and when i called them, they said they didnt have one, but the DID have one that was included in a package of engine gaskets,, so, i goes you have to be broad with your do yo have questions
Thanks, I’ll try a GM source using the MPL part number.
FOUND ONE..... Mahle/Victor Gasket on Amazon. P23883 Axle Housing Cover Gasket is how it is described, $12. Thanks all
Dan,
I might suggest that before you start chasing leaks, clean the area completelt to bare metal (or paint if it is there) and drive it a couple of blocks. You should then be able to determine the source of any and all leaks.
Greg Surfas
That’s exactly what my plan is! I intend to clean it thoroughly, Drive it and try to identify the leak. I’m confident that the cover seal is seeping, my concern is that the drive out put shaft seals are leaking as well..but clean and drive will tell
My money says its not the axle seals. Some of the replacements
are not really up to the standard of the originals. Is it gear lube
or trans fluid?
Note also, there is a pair of seals between the trans and the
final drive, and a small vent in the area. Might have a piece
of wire sticking out. Bruce Roe
Good suggestions! I’ll look into those areas. Really need to get is all cleaned up then drive it and see what manifests
Check to be sure that vent isn't plugged. It could be mostly dry but leaking when the pressure builds up.
Jeff
YES! A plugged vent will cause the case to be pressurized and blow seals, had that happen on a transmission once!
Quote from: danjarrett1 on January 02, 2018, 11:54:25 PM
FOUND ONE..... Mahle/Victor Gasket on Amazon. P23883 Axle Housing Cover Gasket is how it is described, $12. Thanks all
Do you have a link??
Amazon. Can’t forward the link from here found it on amazon
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.
If the mileage is high and the bearings and seals are worn, then gaskets won't help (unless it's just the diff cover leaking). Seepage around the pinion seal is a tell tale of gear wear and loss of proper lash.
Quote from: TJ Hopland on January 08, 2018, 09:27:48 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
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.
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
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
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?
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
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
Thank you.
Bruce. >:D
Said I would post pics of the gasket I found, here it is:
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