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Cephas · Joined: 02 Mar 2003 Posts: 767 Location: Chicago

Hey board. I've been away for awhile. Studying for finals and all has taken too much time. That and the fact that my work has begun monitoring on-line activities

have rendered me unable to enjoy the board. But I've got a pressing issue to ask about.

Here's the deal. I'm leaking tranny fluid from what appears to be the rear main seal. I already know that I need to replace the center bearing on the driveshaft as well as the guibo's. While the driveshaft is out, I was planning on replacing the rear main seal. Can this be done with the transmission still in the car? I'm assuming it can, but if anyone who's "been there" could verify that for me that would be great.
For now the E30's sitting. I won't drive it until the problem is fixed as I'm unsure how much oil has leaked out of the trans.

Thanks all!
-Peter

85-325e · Joined: 30 Jun 2002 Posts: 4712 Location: Southampton, NY

Nope, not if it's the main rear engine seal it can't. You have to remove the muffler, the heat sheids, the driveshaft, the tranny & clutch, then the flywheel. Then you'll be exposed to the rear of the engine. If it's ONLY your rear transmission seal, then yes, you could.

Remove the muffler, heat sheilds, the driveshaft. Make sure you don't hurt the drive shaft and retract the end of it as bit before you try to get it out. Then, you have to remove the flex coupling at the end of the tranny. That's a pain in the butt, but you can do it. When I did mine two years ago, I built my own tool to hold the flex coupling while I tightened the nut with the special deep socket. Here's the tool I made to hold that baby tight:

I made it out of walnut or some other hardwood, and then painted it. I'm sure there are many other methods, but you'll HAVE to have that 34mm Deep Socket I think. Once you get the flex coupling off, the seal's right behind that and you can get it out with a seal puller (CAREFULLY). Then press the new one in, reassemble, wrap it with a big bow and place it under your Christmas tree as a gift for yourself!

peerless · Joined: 12 Nov 2003 Posts: 1721 Location: Orange County, Ca

I am going to take a shot in the dark and assume that Cephas is talking about the rear tailshaft seal on the trans.

And yes it can be done without pulling the transmission although it wont be a lot of fun.
Basically remove heatshielding and driveshaft.
Using a jack to support the trans undo mount bolts from body and lower rear of trans as far as it can.
Then the yoke. 30mm thinwall socket required.
Pull and replace seal. Also don't forget to replace the shift selector shaft seal. This ones a real bitch to get to with the tranny in the car. But they leak more then the rear shaft seal from what I understand.

Bentley highly recommended

Robert
85' 325e

Cephas · Joined: 02 Mar 2003 Posts: 767 Location: Chicago

Peerless is right. I believe that it is the rear main transmission seal. I'm probably going to let my mechanic tackle this one as this is my finals week right now. I don't have the time to get to it. While he's at it I'm having the driveshaft bearing and the 2 flex disk guibos replaced as well. I'm glad it can be done with the trans in the car. That will save me a good deal of money. Thanks for the input guys.

85-325e: You're quite the craftsman! That's a great looking job you did on that tool.

85-325e · Joined: 30 Jun 2002 Posts: 4712 Location: Southampton, NY

Thanks Cephas! Actually, it was out of necessity. That flex coupling end to the tranny is a BEEEEEAAAATTTCCCHHH to get on there right... And I didn't have the proper tool (I'm sure there's a perfect one from BMW or somethig like that) and I didn't have any money at the time, but I did have the hardwood, and time, and it was the only way I could think of holding that bolt. The tip of that "wrench" actually fits snugly in the coupling!

Just remember that oil leaking can travel across horizontal surfaces and come out looking like it's leaking someplace else. But Peerless is correct... you should have the top seal done as they tend to leak faster than the one at the back, although both could cause a gooey mess!

[ 05-16-2004: Message edited by: 85-325e ]

dale · Joined: 22 Aug 1999 Posts: 3087 Location: Seattle, WA USA

I've been able to do this without removing the driveshaft. Just push the front portion all the way back on the splines, doesn't hurt to clean those splines first after removing the exhaust and part of the heat shield.
Then pull the guibo, remove and dreplace the selector rod joint, replace the selector shaft seal while you are at it, remove the output shaft with 30mm socket.
I bought an impact socket and brought it to a machine shop, $10 or so and he cut the wall thickness in half for about 1/2" back from the end. Worked great until I broke it on my 200 ft-lb rear axle shafts.
Replace rear seal, replace nut and reassemble everhthing.

Dale

Cephas · Joined: 02 Mar 2003 Posts: 767 Location: Chicago

Well, I thought I'd update. There was no transmission leak after all. It was the power steering leak that I've been putting off till school is out. 85-325E, man are you right. That stuff had traveled all the way to the tail end of the trans! Here's the cool part of my story. I had it towed on Monday to my mechanic. They called me up later in the day saying that the car was done, they had replaced a broken bolt on the rear transmission carrier. Apparently one of the bolts holding up that crossmember that the trans mounts sit on had snapped the head off. So for $80, the shop had fixed my power steering leak and drilled out and tapped in a new bolt. Not bad at all. My shifter has never felt tighter. I thought I needed new bushings and have been contemplating a short shift kit, but this thing feels like new now. Check those mounts and that carrier if you guys have much fore and aft play in your shifters, they could be going bad.

Thanks for all the tips!
-Peter

85-325e · Joined: 30 Jun 2002 Posts: 4712 Location: Southampton, NY

Peter...

Glad to help!!! I'm no great mechanic, but I've seent hose things before in my own car. Oil was leaking slightly from the main engine seal, but it was dripping at the back of the transmission. Don't forget that when something's leaking AND you're driving, there's strong air flow beneath the car, pusing anything that's dripping towards the back of the car...

Be happy that you got away cheap, and that you were pretty lucky! Unfortunately, sometimes a leak IS coming from where you think it is!!!

menuhin

85-325e · Joined: 30 Jun 2002 Posts: 4712 Location: Southampton, NY

1. Yes... It's MUCH easier to do it all with the tranny lowered. It's pretty tight up there...

2. You can use regular engine degreaser... just spray it on, let is sit a while, then hose it off.
_________________
Cosmo - 1985 BMW 325e, Single Owner, 265,000+ ORIGINAL miles and still going strong! But now on the East Coast and the salt air corrosion is eating my beautiful car alive... Sad

Ken Juul · Posted: Mon Jun 30, 2008 11:06 am Post subject: Locknut

Glad it's so easily fixed. Some additional information for future thread readers. The nut that holds the output flange has a bent over locking tab. If you change it on the car it is very hard to see, just know it's there. Had me scratching my head trying to figure out why my socket wouldn't go on the nut.