OK, so last weekend out of nowhere, the output shaft started leaking

It had been sitting for over a week while I was out of town and not a drop was found on my floor.

Then I pull into my shop and while putting her on the lift to check the brakes and whatnot, I noticed a small drip which turned into a puddle within the next 1/2 hour

Checked the U-Joints and one was bad, so I replaced them along with a new output shaft seal and all was good

Took her out for joy rides multiple times this week and again, not a drop was found on the floor

Then earlier today, I pulled her out from the back of the shop to the front so I could mess around with her this weekend.

Probably had her running for no more than 5 minutes and parked.

After sitting for an hour while I welded up some lift off hood extensions, I now see another puddle on the ground

I'm gunna replace the seal again to see what happens, but I have a funny feeling I may have other problems as she was actually ~3 quarts low when I got her just a couple weeks back

 

Replace the out put shaft bushing. Check the yoke for extreme wear. Should be shiny,but not grooved. Do you notice any hi freq vibes at road speed?

 

Check and make sure the Yoke is not what is leaking. I would clean it off. make sure of where it is leaking. IF you need to replace the tail shaft bushing that can be done without removing the trans. Just need a bearing driver

 

The yoke didn't look bad (I've seen worse), but it did have a couple of black lines that I buffed off with some 1500 wet.

When I first got her, there was a bad vibe when slowing down from speeds above 80mph, but after I replaced the U-Joints, most of the vibes went away.

When I had it apart for the U-Joints, I checked the seal on the back of the yoke and the clips were still in place.

Cleaned off all the loose grease, then filled the yoke with fluid tried forcing it down with a plastic plunger to check for leaks, but got nothing.

Is it supposed to be completely sealed?

The GM yokes actually have a little vent hole that most people seal with silicone


Has anyone here done a write up on this?


Also, would a bad bushing cause it to leak suddenly like this and lose so much fluid?

I know the pans on these things are quite shallow compared the GM/Ford, but there looked to be about 1.5 quarts on my floor

Didn't check the level with the dipstick, but I dropped the pan about an hour ago and it seems to be full

Put a new filter, gasket and replaced the seal (before reading the replies) and I'm about to refill.

 

Snake -

Gonna take what TV said a step further. Any chance of it coming from somewhere else and just flowing to the real seal area?

Been burned by that a few times.

Archer

 

Both times it was dripping right out of the dust boot.

Even wiped it clean and watched it drip some more

Just got back from a little joyride parked it in the same spot.

Didn't put her back on the lift cause I needed to work on my Land Cruiser, but she's parked in a dry spot and I'm just hoping I don't see any puddles in the morning.

 

I hate to say this but I have to agree with archer. The rear seal area of the transmission does not normally hold that much oil. It is not under pressure and would not suddenly drop that much oil. The speedo gear assembly usually leaks before the rear seal does.

If someone played with the transmission at one point there is a pin that holds the reverse band bracket assembly that has an o ring on it. These are prone to leakage as most rebuilders havent got a frigging clue how to put them in. You have to lube the stupid thing on install or the new oring is cut and it leaks.

The front yoke should have an air hole in it. at the back of the yoke should be a washer that is peened in. The center should have a tiny 1/16 hole in it.

If the rear bushing is bad you should be able to take the drive shaft and move it up and down about 1/4. Normal wear puts them about 1/8 in total side to side play.

There is another possibility however. It may be that the seals you are installing the spring on the back is popping off as you install them. Without the spring there to keep it tight the rubber of the seal will only last a short while till it starts leaking again.

When you install the yoke into the transmission on a new seal you should also be putting a light coating of grease on the outside of the yoke. Dry seal damage is also another cause of early failure.

 

Didn't see any hole, just looked like a round disc behind the U-Joint

There really isn't much play at all at the front yoke.

The pinion has more, but nothing out of the ordinary.

Both seals still had the spring on the lip still in tact with no abnormal wear

I didn't use grease, but I did dip the yoke in fresh ATF to coat both the inside and out.

It slipped in with ease.


Anyways, I Googled "727 Torqueflight Leak" cause the search feature here wasn't coming up with much and found a thread on another forum.

Read an interesting (and scary) post



Makes sense, but I really hope I don't have this problem

 

BTW, I installed the new seal with the hole on the bottom this time

 

The Mopar YOKE does NOT have a vent hole !!! It has a cut away spline and it vents back into the transmission. IT''s not a cheby

Are you using a OEM seal ?

IF the front pump bushing was bad I would suspect the seal in the pump would be leaking esp if it is a 40 year old seal

 

You mentioned you sanded the yoke.
i had a rear seal leak issue there was a groove in the area where the seal contacted the yoke surface, after i replaced the yoke the leak stopped.
some times you can use a different tail shaft seal that rides along a different area of your yoke.
Also another area of leakage is the gear selector/pressure, shaft seals.
Because i manually shift mine the seals last a few years,
The tail shaft housing can be removed with out removing the trany.
You need to access the tail shaft housing bolts and you need a expanding-ring pliers to unlock the out put shaft roller bearing from the housing. [small access plate]
you can remove the roller bearing from the shaft and replace it, and you now have better access to the pressed in yoke bearing in the end of the housing i have a tool that pulls this bearing, but you can take yours to a local trany re-builder and have him replace it.
Also while your in there you can change up your governor weights and reprogram your shift rpms if you want to raise them. there are some kits available.

"The pinion has more, but nothing out of the ordinary."

For me any movement in the pinion is out of the ordinary, that's going to destroy your universals and your trany let alone the rear end.

 

OK, a little update.

Last night, after installing a new filter kit and output shaft seal, I took her for a little joyride, came back and checked the fluid.

It was right below the full mark idling hot.

Shut her down, let her settle a few minutes, checked the fluid with the engine off and it was right above the full mark.

Left her overnight and now there's a small puddle near the front of the trans and I'm pretty sure it's coming from the dipstick tube

Anyways, I just checked the fluid level with the engine off and it's way above the full mark

Currently doing some rewiring, so I'll check her again while running in a little while.

BTW, I'm running a reverse manual valvebody if that makes any difference with the converter draining down

 

Checking the fluid with the engine off is useless. Has to be hot, running and in neutral.

 

Yes, I know this for checking proper level, but what is considered a normal level when the engine is off?

Reason I ask is if the converter is dumping fluid back into the pan, no seal will hold up if it's overfilled

 

dipsticks have an oring. Replace oring and put some silicone on it to slip it in. Not a big deal. It could be the front seal or not.

Watched your video and well please don't take offense but it sounds horrible. This is typical for headers and non stock mufflers with a wonky non stock cam though so it really doesn't suprise me.

 

None taken

I don't expect anything to sound good from from tinny GoPro audio (especially from one mounted on a sway bar), but it was either that or music and I already know you don't like my music

 

I'm not real familiar with the 727, but if it seems to come of the dipstick tube I've had a similar issue with this... I had a 40 ford pickup I restored the summer before last. Put a 355 and turbo 350 in it. And it did the same thing yours does only worse. You could go out and drive it and bring it back and pop the hood on it after about 5 minutes all kinds of tranny fluid would be forcing its way out of the dipstick tube. On the the turbo 350 there is a little vent tube on it. I had a hunch that it could be clogged and not letting the tranny breathe right so I took an air compressor and a piece of fuel line. Taped the fuel line on to the vent tube and stuck the blow gun in the opposite end blew it out and it completely fixed that issue. Like I said not familiar with 727's but this may help you out. Not sure where the vent tube is on them but I'm sure they have one some where.

 

I've been curious about this ever since I had to top off the fluid when I first got her

The dipstick tube in question isn't really a tube, but some fancy braided line plumbed into the stock hole and although it looks pretty cool, it has a plastic dipstick that can be tough to read at times

Also, the opening is very small and I can't fit a proper funnel, so I have to use screw on cone tips from gear oil bottles to fill and that takes FOREVER

While squeezing the bottles down, it felt like there was no air escaping the trans to let the fluid flow.

 

Yeah I would definitely try finding that little vent tube and and blowing it out. Good chance it could be doing the same thing that turbo 350 did. You may even trying blowing the dipstick tube out if you could figure out a good way to seal it to a blow gun.

 

I would get the stock dipstick !!! If for no other reason to make sure you have the correct level of fluid

The stock dipstick has a vent hole about an inch down from the top about 1/8"

 

There is no holes in the stock dipstick tubes ever. They vent through the top of the dipstick itself. It's why the flat metal is peened on each side and a slot in the metal top. It prevents fluid from escaping but not air.

Chrysler transmission dipstick tubes are always bent in some way so that fluid runs down the side of the tube. It's best to fill transmission fluid with the engine running and transmission in neutral (unless it's a bone dry in which case you put in 4 liters of dex III first).

 

ATF-4 is a really nice fluid and its Mopar approved i'm running it in my 46re.
TVLynn i have seen those vent holes your mentioning

 

The vent hole on my 904 isn't on the tube but the cap, immediately adjacent to where the handle sticks through.

 

OK, back to this thread again......

A while back, I had my trans guy replace the tail shaft bushing while tracking down a vibration problem and had him install a new seal.

I explained the way the leak occurred and he said it's actually common among Torqueflites

The issue isn't the seal itself, but the converter siphoning fluid back into the pan.

When the pan is eventually overfilled, the fluid simply forces its way past the seal

He said Chrysler later fixed this problem by putting a check valve in one of the lines (can't remember if he said the pressure or return line), but doesn't recommend doing so because if the check valve ever fails, I'll end up smoking the trans

Anyways, I haven't seen a drop since he installed the bushing and seal, but I had been driving it everyday.

Unfortunately, I blew the rear end a couple weeks ago, so she's been sitting since then

I finally have the 3rd member built and ready to bolt on and just today while I was taking the cover off to get her on the lift, I shook her a little slamming the trunk, then all of a sudden she started pissing ATF out the seal again :banghead:

Put a good quart on the floor within minutes!!

My trans guy actually suggests putting a manual hand valve on the line and locking it off when I know she's gunna sit for a few days....