Leaking "U" joint? - 1966 Cadillac Sedan DeVille

[comyboy]

Okay.  So I'm pretty sure "u" joints don't leak.  At first I thought it was the Extension Housing Seal but at closer inspection I can't see fluid coming out of there.  Had a few other people check.  It seems like transmission fluid but I've lost about 8-12 ounces of it in the last 24 hours or so and my reservoir hasn't gone down.  I can't see any fluid leaking toward that location to cause the pooling of fluid and the drip.  Is there a brake line above this piece?  Anyone have this problem before or know what it is?  I'll get it up on stands this weekend for a more thorough inspection.  I just wanted to be able to get the parts before I got underneath it.  Thanks in advance for any help you can provide.

The first pic is from the drivers side through a mirror because the exhaust is in the way and the other pic is from the passenger side.

[Steve Passmore]

Hi Cowboy, I have seen this happen before and your right, UJs dont leak fluid, its coming out of the transmition through the inside of the spline tube, this usally happens when the spline is a little worn and the fluid is able to work its was inside the splines, some spline shafts have a small hole in their Yoke end to the inside of the UJ and it then leaks out from there. You may be able to plug this in some way? HTH

[12138 Joe]

I've been through this before myself on the first generation TH400 with switch-pitch.  Orginally, the sealing of the rear of the transmission involved an "O" ring which is slid over the splined output shaft. When the driveshaft yoke is pushed in, it seats the "O" ring to keep fluid from leaking back to the rear along the splines. THE CENTER OF THE DRIVESHAFT YOKE IS DRILLED WITH A VENT HOLE. If the "O" ring is present and in good shape. this venthole relieves air or fluid pressure when the yoke travels in and out of the transmission with normal driving......(something has to have some give or allow movement somewhere). The O ring keeps oil leakage reduced at that venthole.  An alternate method of dealing with the lost, broken, missing or misseated O ring is to plug the drilled hole in the yoke; this will work, providing that tha O ring is gone or useless. Remember, something has to "give" somewhere, to reieve the hydraulic pressure that can build up along the splines when the yoke moves in and out. The downside of using the quick fix of plugging the vent hole is that when you put the car on a hoist, and the yoke has maximum movement when the rear end drops down, it MAY puke a small amount of tranny fluid out at the rear seal, but everything will be back to normal when your back on level ground.

[comyboy]

thanks steve.  so you think i should replace the yoke then if the splines are causing it?

thanks Joe.  what'd you do to fix yours?  i had a response on another forum that said he put por 15 on the seal and let it cure for two days and the leak stopped.  do you know where to get the "O" ring or what it's called?  i don't think my shop manual says anything about it.  thanks again!

[bcroe]

If it is coming from the vent hole, replace the output shaft O ring that is just forward of the splines.  This can be done without removing the trans, by taking out the driveshaft & rear tailshaft housing. 

On the other hand, this might be an indication of the condition of much more important seals in the transmission.  Any trans that age should have a rebuild, so that a clutch pack piston seal won't let go and burn up, an expensive mess. 

Bruce Roe CLC # 14630

[comyboy]

thanks bcroe.  any idea on where i get one of these "O" rings?  is it a standard size that i can just measure and order?  is it called the slip yoke seal?  or slip yoke "O" ring?  i've called a few parts stores, looked online, and called a few transmission shops and no one can help me besides you guys on here.  thanks!

[comyboy]

an update on the leak...

so my car was parked in my driveway at an angle with the front end facing the house.  leak was continuous.  maybe one drop every 10 seconds.  i think i'm at about 20 ounces of fluid lost.  i started the car and backed the car down to the bottom of the driveway and the leak stopped.  i drove it around the neighborhood about 3 miles checked it again and no leak.  i backed it up the driveway and still no leak.  but my reservoir hasn't gone down at all.  with 20 ounces of fluid lost, that top of the little reservoir should be empty.  any ideas?  the fluid is definitely red.  thanks!

[The Tassie Devil(le)]

Park the car with the nose facing downhill.    Steeply downhill.

Bruce.

[comyboy]

haha.  done.

[bcroe]

I don't know what you mean by the " little reservoir ".  The trans pan holds a gallon.  To get at the O ring, you will need to remove the drive shaft.  Then probably drop the tail a couple inches, which might require removing the trans support.  Then remove the 6 bolts and the tail extension, and the output shaft is exposed.  There is a slim chance your trans has an output shaft with NO O ring groove, but your driveshaft yoke requires one (messed up rebuild). 

The O ring is in every trans rebuild kit.  Maybe I have a spare from the other type, if you can manage the above. 

Bruce Roe CLC # 14630

[Steve Passmore]

I'm confused by the "reservoir" too comyboy, are you sure your not mixing up your transmission fluid with your brake fluid? you have to dip the gearbox for fluid level. don't you??

[comyboy]

But the top part where the little dip stick is is only 10 inches around and only may 6 inches tall.  i would be able to see 20 ounces of fluid disappear.  so woke up today and still no leak now that the car is parked downhill...

[The Tassie Devil(le)]

I am totally confused with this part.

I think we need a picture, or two.

Bruce.

[mgbeda]

I'm no '66 expert, but are you sure you aren't looking at the power steering fluid?  ATF can be used there too in old cars.

I had a '76 Coupe that leaked only when she was pointing uphill too.  And I really did "solve" that by only parking downhill.  But that was in my younger carefree and ignorant days.

-mB

[comyboy]

well here are the pics.  it's the housing with the silver colored cap.  says fill only with transmission fluid type "A".

mb, did you ever find out why your 76 was leaking while uphill?

[The Tassie Devil(le)]

Ah ha.  .....  The Power steering Pump.

That explains a lot.

Maybe you also have a leaking Power steering Hose as well.

The Transmission Dipstick is at the rear Right Hand Side of the engine, and goes down to the Transmission.

Bruce.

PS.   The Power Steering uses the same fluid as the Transmission.

[comyboy]

oh man this is gonna be a long weekend.  good thing you guys started firing questions at me.  now i'm thinking baby steps...  thanks for all the help guys!

[Steve Passmore]

Ha Ha, no wonder you weren't seeing any fluid go down comyboy. still back to the spline yoke then, Id park the other way around and leave it unless it became a real problem.

[The Tassie Devil(le)]

I hate to say the obvious, but me thinks you need to get hold of an Owners Manual, and a Workshop Manual, as soon as possible.

Bruce.

PS.   Oh, and read them from cover to cover.

[comyboy]

yep.  i have the original owners manual and the original shop manual.  i just like jumping to conclusions.   btw, pointing out the obvious helps me too.    i'd like to fix the slip yoke problem now but i can't find anyone with parts.  i think i'll wait until i have a few days off and then tackle that problem in case i can't find a part for it.  if anyone runs across the seal/"O" ring/vent please let me know. 

thanks again for the help guys!