Tranny Tailshaft Seal Replacement

N

Neontail97

Registered
My transmission tailshaft seal is leaking. Its dripping on the exhaust so I smell it every time I get out of the car.
The service manual says to unbolt the differential to remove the driveshaft. Is there anything else to it?
Does anyone have any words of wisdom on this job? It looks like there is enough room to get at the seal without removing the exhaust.
Thanks
 
RE: Tranny Tailshaft Seal Replacement

Daughter #2 has a Mercury Cougar that is now leaking after being hit in the rear (it has the same tranny as the Marks. According to the service manual, I must drop the fuel tank to remove the driveshaft. Then I have to remove the exhaust system from headers back to get at the tranny. You have to unbolt the tranny and motor mounts so that you can angle the tranny down to get clearance for the special tools needed to extract and install the seal.

It such a big PITA and I lack the special tools, I'm thinking about going to a tranny service guy and see how much they would charge me to do it.
 
RE: Tranny Tailshaft Seal Replacement

The differential can stay put, but the gas tank has to come down. The exhaust on my car would definitely have to come down, if you have stock exhaust it would probably have to come down as well.

You should be able to skip the special tools.

I'd start by pulling the driveshaft, which of course involves dropping the exhaust and gas tank. Then see if you can pry the old seal out with a screwdriver. With the output shaft protruding through it, that may not be possible. But it should be rather simple to remove the housing, at which point you could easily pry the seal out with a screwdriver, and even replace the bushing in there as well (although that requires access to a press).
 
RE: Tranny Tailshaft Seal Replacement

In my experience, most seals start leaking due to a mechanical reason. Usually a tailshaft seal means the tailshaft bushing. If it were mine and I planned on keeping it, I would look into replacing the tailshaft bushing. Now would also be an excellent time to have the u-joints replaced as well. At the very least you owe it to yourself to carefully examine these items while you are there.

Make absolutely sure the driveshaft is indexed with a permanent marker at both ends prior to removal! Reinstall the driveshaft properly indexed to maintain balance.

All this applies whether you do it yourself or job it out.
 
RE: Tranny Tailshaft Seal Replacement

I had a tailshaft leak - drip, on my 98 Mark. I had the seal replaced when I had the new MMDS installed. No leaks or shakes for a couple years now.

Jason, Do you have a stock, or Metal Matrix drive shaft? If stock, the drive shaft vibration might be your root cause for the seal failure. Good luck!
 
RE: Tranny Tailshaft Seal Replacement

Thanks all for the good tips. I have a stock driveshaft and exhaust but do not have vibration.
I'm pretty sure I can get the seal out with the variety of homemade seal removeal tools I have. I too am concerned why the seal failed and if there is an underlying reason. I am at 86k and did the 1-2 upgrade/mercon V and filter at 50k. Didn't see any signs of abnormal wear at that time. Very little accumulation on the pan magnet.

QUESTION: If the bushing is worn, will I be able to tell by checking for side-to-side play in the output shaft? How much play would be normal?
I am not looking forward to removing the exhaust most of all. The bolts are looking a little rusty. Nevertheless it can't be as bad as replacing the rusted out oil pan on my 94 F-250. I would rather change 20 blend door actuators rather than do that job again.
 
RE: Tranny Tailshaft Seal Replacement

Just let the rusty stuff soak in WD 40 for a few days before you try to remove it.

The tailshaft doesn't come into contact with the tailshaft bushing, the driveshaft does. So if there is any noticeable up and down movement of the front of the driveshaft, that bushing should be replaced. You can't find the bushing at a dealer, though, they'll try to sell you the whole tailshaft housing. call around and find out where a local tranny shop buys their parts, then go there and buy the bushing. Should be $5. The dealer will try to sell you the whole housing for about $110.
 
RE: Tranny Tailshaft Seal Replacement

Keep in mind, like the seal, something made the bushing wear out :) . Tailshaft bushings just do not go bad unless it got some help from somewhere. Like Dave said, the driveshaft touches the bushing.

Not to beat a dead horse, but I still believe you will just bandage the problem if the drive shaft is not balanced or replaced.
 
RE: Tranny Tailshaft Seal Replacement

You could just let it leak. I have a leak from my transmission on my truck, and i'm just going to keep adding fluid.
 
RE: Tranny Tailshaft Seal Replacement

[div class="dcquote"][strong]Quote[/strong]
Not to beat a dead horse, but I still believe you will just bandage the problem if the drive shaft is not balanced or replaced.
[/div]

From what I understand the 2 piece shaft cannot be balanced. Either need a 1=piece from a '93 or a MMX shaft.
 
RE: Tranny Tailshaft Seal Replacement

Jason, you shouldn't need to take the exhaust or fuel tank down to fix the seal. The shop manual is correct. This is the way we do it at Ford dealerships:

-Drain the transmission by removing the pan (if needed).
-MARK THE DRIVESHAFT AND PINION FLANGE.
-Undo the rear driveshaft to pinion flange bolts. Pry the shaft free; it will be stuck to the flange.
-Support the differential housing and undo its mounting bolts. Lower the housing which will be supported by the half-shafts.
-Slide the driveshaft rearward and you'll be able to push it back and over the now hanging differential far enough to get the slip yoke out of the extension housing. Bungee it off to the side and do your seal. The shaft can't fall; it's supported in the valley of the fuel tank. (Our "transmission specialist" uses this method when he removes Mark/T-Bird/Cougar transmissions, leaving the driveshaft behind, resting on the fuel tank).

Changing the bushing is a very good idea, and Dave's absolutely right. Ford will try to sell you a whole extension housing. Take yours out and have an aftermarket bushing pressed in.

Taking the driveshaft right out of the car for repair, or removing the extension housing, will leave you with no choice. The exhaust has to come off. Support the transmission and take the crossmember out. Disconnect the VSS/OSS and take it out. Unbolt the extension housing and slide it over the tailshaft. The driveshaft is the fun part. If you stick your tongue out of the side of your mouth, close one eye, and curse a lot, you'll now be able to wrestle the driveshaft forward beside the transmission and out of the fuel tank valley. This is a lot of aggravation. It's usually more straightforward to just lower the tank.

I hope you have access to a hoist. I wouldn't envy you doing this in your driveway.
 
RE: Tranny Tailshaft Seal Replacement

If I were doing the job I would drop the rearend down, slide the driveshaft back, remove the entire extension housing, do a force lube mod on it with a new bushing and seal.
Alan
 
You must log in or register to reply here.
Back
Top