Transmission Leak! Any Advice?
 

Last weekend, I jacked up the rear end and cleaned the transmission with brake clearer (I thought I was ready to put the engine back in). Afterward the transmission started leaking and about a pint came out before it stopped. The car has been in my garage for about a year, with no signs of leaks.

Could the leak be the result of jacking the car up, or do I have a leaky seal, or something? I’m getting anxious to put the engine back in, but I keep running into problems! From the best I can tell the picture below shows the source of the leak. The car is a ‘744 911.

I’d appreciate any advice.
http://forums.pelicanparts.com/uploa...1095540557.jpg http://forums.pelicanparts.com/uploa...1095540620.jpg

Looks like the shift rod seal doesn't it? You might have a quantity of gearlube in the tunnel as well. Take a look. If so, drop the drivetrain all the way and replace it.

Sherwood

I just found the technical article on Pelican's site that shows how to replace the shifter seal from inside the car. This seems easier than removing the transmission. Anyone have an opinion?

"I just found the technical article on Pelican's site that shows how to replace the shifter seal from inside the car. This seems easier than removing the transmission."

Uhh, your pic showed the engine partially out. Sorry for the incorrect assumption.

Sherwood

Looks like the shaft seal. Replace it with the trans/motor in the car. Usually damaged by letting the shaft hang on the chassis when R/R the trans/motor.

Tinker

Thanks for the advice. Next time I'll support the transmission when I remove the engine.

Tinker is right. You see this alot. If you look at most of our cars where the shift rod goes into the tunnel you'll see where the hole is damaged on the top from the shift rod wedging against it. You have to loosen the trany mount more and support the bell housing area to keep this from happening. One of my cars had a bent shift rod from this. The only way I could make it seal was to machine an aluminum piece to take a seal and epoxy the aluminum onto the tranny case aligned with the new center of the shift rod.

If the shift rod is only slightly bent you can minimize the leak by parking the car in second gear. This pulls the rod out of the tranny and makes it off center the least allowing the seal to well...seal.

-Andy

Replacement of that seal while the transmission is in the car is damn-near impossible. Notice that the tech article is for a 356 (I think) which has much more access. I tried for a couple fruitless hours to get that sucker out then finally dropped the transmission as well (I already had the engine out).

With the trans out, it took all of 5 minutes.

Okay, the last post did it. The transmission is coming out. Thanks again for all the input.

Patience Grasshopper, it is do-able. You need to jack the car up so you can work both inside and underneath.

Tinker

Don't ever use brake clean to clean a motor or anything else with rubber seals/components incl. hoses .It actually swells rubber and makes it very prone to tearing....spray some on a latex glove or old diaphragm and see what it does .not good .

Now is the time to replace all of the seals on the tranny. If one is going or gone, the rest will not be far behind.

Transmission Leak - Phase II
 

After taking some time off, I pulled the transmission out. The machine shop guy that helped me with the engine told me that I probably bent the shift rod (without seeing it). Besides the angle looking a bit off, it looks okay to my inexperienced eyes. Does anyone have a different opinion from looking at the pictures below? http://forums.pelicanparts.com/uploa...1097350428.jpg http://forums.pelicanparts.com/uploa...1097350487.jpg http://forums.pelicanparts.com/uploa...1097350548.jpg

Doesn't look to bad to me.

Put it in either first or third (push the shaft in or out to engage a gear) and then second or fourth and check with your straight edge.

It would need to have a pretty noticable bend to cause a leak. The shift shaft is pretty strong, unless you bent it with a floor jack while raising.

Now that you got it out, do yourself a favor and clean the case so you don't get gear oil/grease every where while installing.

Tinker

Here's an idea. Have no idea whether this will work:

Drain the gearbox then refill with a quart of 30 wt. engine oil. Observe the leak rate (x drops/minute). Drain the gearbox again, replace the seal and see if the leak is the same as before. If the shaft is bent and off-center, the leak rate will be the same; old or new seal.

Sherwood

Change the shift rod seal and all is done. The rod looks good and you check it. You may no have problem with it.

Charley,

You have already done the hard work to get the transmission on the bench. Take it apart, inspect everything, and replace all the seals and gaskets. Not a big deal or expensive. Use the opportunity to clean and inspect everything. With the shift shaft out, you can properly measure any runout.

Best,
Grady