300sdl leaky transmission - PeachParts Mercedes-Benz Forum

ah-kay · #1 06-09-2009, 02:50 AM

I have a leak in my transmission. It is leaking from the circular part as shown in the diagram. It is on the right hand side of the transmission. The circular disk can turn in both directions. What is it? How can I take it out and fix the leak?

amosfella · #2 06-09-2009, 03:40 AM

It looks like your B2 piston. Might need to get a reseal kit. search for B2 in the forum.

tbomachines · #3 06-09-2009, 07:19 AM

X2, You'll just need a rubber o-ring for that cover. If your transmission shifts funny you might want to replace the piston/bushing while you're down there. Removing the cover is a bit tricky, there is a circular spring that retains it, you have to pry it off.

ah-kay · #4 06-09-2009, 11:48 AM

Quote:

Originally Posted by tbomachines

X2, You'll just need a rubber o-ring for that cover. If your transmission shifts funny you might want to replace the piston/bushing while you're down there. Removing the cover is a bit tricky, there is a circular spring that retains it, you have to pry it off.

The transmission shifts good. Is it possible to do it with the transmission is the car? It seems to be a very tight down there.

Thanks for the info.

tbomachines · #5 06-09-2009, 12:03 PM

As long as you're just replacing the O-ring, you can do it on the car without too much trouble. It is tight down there but you don't need too much room to pop the cover off. I ended up cutting a wooden dowel and lodged it in between the cover and the transmission tunnel to keep the cover depressed while prying out the clip.

Visually check the B2 piston while it is in there, as long as it isn't in pieces you're probably okay for now. If it is shifting ok then you are probably fine as well, but can't hurt to take a mirror and peer in there to make sure. If you were to replace this, you'd need to loosen some mounts and the driveshaft support bearing to shift the tranny over a few inches.

Dieselgiant has a pretty good explanation of the o-ring replacement process, exactly the same problem that you are experiencing:
http://www.dieselgiant.com/Mercedesb2pistonsealreplacementl.htm
You won't have to pull the piston out.

mplafleur · #6 06-09-2009, 12:38 PM

Dieselgiant's pictorial is pretty good.

I had to replace the seal on my B1 cover, which is the other one closer to the dipstick tube. The springs behind it exert a LOT of force on the cover. I JB Welded a large nut on the center of the cover and used a turnbuckle with a carriage bolt on one end centered on the nut to get everything back in place again. I hope the B2 springs aren't that bad.

tbomachines · #7 06-09-2009, 12:42 PM

My B2 wasn't too bad, you could definitely push the cover in with just your hand. It was slow though, the closest thing I can think of is pushing air out of an air mattress or pool float, it didn't take a lot of force, but you had to keep it on there for a minute to let it sink back. Lodging the piece of wood in there just allowed me to use 2 hands on the clip.

ah-kay · #8 06-09-2009, 01:37 PM

You guys tips and insight is invaluable. Down on my back tonight.

BTW, where can I buy the o-ring off the shelf, from dealership or autoshop like Kragen?

mplafleur · #9 06-09-2009, 03:14 PM

Quote:

Originally Posted by ah-kay

You guys tips and insight is invaluable. Down on my back tonight.

BTW, where can I buy the o-ring off the shelf, from dealership or autoshop like Kragen?

I bought my B1 O-ring from the dealer. It was $3.

ah-kay · #10 06-23-2009, 02:00 PM

Fixed the transmission leak. Bought the O-ring from dealership but he gave me the wrong one. It was too small. I needed to take the B2 cover plate to the dealership to show them before they came up with the right O-ring.

BTW: the old one must be the original one as it was brittle when I removed it.

Thanks for the experts in this forum.

tbomachines · #11 06-23-2009, 02:45 PM

Good to hear! Though I would not consider myself an expert by any means

mplafleur · #12 06-23-2009, 03:28 PM

Quote:

Originally Posted by ah-kay

Fixed the transmission leak. Bought the O-ring from dealership but he gave me the wrong one. It was too small. I needed to take the B2 cover plate to the dealership to show them before they came up with the right O-ring.

BTW: the old one must be the original one as it was brittle when I removed it.

Thanks for the experts in this forum.

The smaller one is for the B1 cover next to the filler tube.