Carrier bearing question for '82 240D

[showme]

Our 240 has a knocking noise under the cab when I'm getting up to speed, but stops when I'm out of the low gears and leveling out on speed. From some of the searches I've found, (and my brake and muffler guys opinion) is that it's carrier bearing needs replaced, and his brother (part owner), threw in the universal joint on the "needs replaced list" just for good measure. I've read on this forum that replacing the u-joint is a bad idea on these cars, but it seems the carrier bearing is ok. My question, besides wanting to know what everyone thinks, is how tough is it to replace the bearing, and what all does it entail? I appreciate any help I can get on this subject. Lee

[hangit]

There are several threads in the DIY section that refer to the carrier bearing. I had a U-joint go bad and had to replace the entire drive shaft. While I was at it , I replaced the flex discs at the same time. Not a difficult job. Not sure about just the carrier bearing.

John

[showme]

Thanks, John, though that's worse than I wanted to hear. It's actually not that bad, I just don't like the sound of something knocking, even if it is only for a few seconds. I've already got the bearing, but I figured I'd see what is said on this post before even attempt to change it. Sure don't want to throw the whole shaft out of wack. Also, the exhaust, though in good enough condition, was hanging by tie wire when we bought it. The shop put new standard American style hangars on it to stabilize it until I can get the OEM replacement exhaust.
I see you're a veggie oil user, too. I took a semester down at San Juan college in Farmington, New Mexico 2 falls ago and helped with a couple of MB Greasecar conversions. Plan on doing the 300 in the spring\summer.

[charmalu]

Lee, changing the carrier bearing isn`t that bad of a job. I thought it was until I did it.
I thought the U-Joint was bad, I grabed the driveline and jiggled and wiggled it and was sure it was the Joint. I could feel looseness it. Called the MB wrecking yard in San Jose and they had one off a 82, for $150.00. I was checking it out and it had the same looseness as mine. the guy wouldn`t sell it to me saying it`s the bearing not the joint. they don`t usually fail.
Ok, so I order the carrier and bearing and a rubber sleeve and have them the next day from Phill. great service.

First thing is to mark both sections of the driveline because you will have to take it apart at the splines. I use some cheap fingernail polish I got at the dollar store, drys fast. Disconnect the driveline from the flex disc at the trans. Loosen the 46MM large nut and remove the 2 bolts that hold the carrier bearing to the body.
Leave the rear disc attached to the driveline but remove it from the Diff.
Then push the driveline forward and it will come off the yoke on the diff. then just drop it down and work out towards the rear.
separate the 2 sections.
I used a bearing puller with 6 or 8 inch arms, and the bearing comes right off. Put the new bearing into the new rubber carrier. I used some spray silicone on the rubber to ease the bearing inplace. clean up the end of the shaft, slip the new bearing on. I used a piece of 1 7/8 exhaust tubing, slide it over the splines and drive it home. I put a large socket over the tubing to beat on. goes on very easy. then I think the rubber sleeve slides on and maybe a couple of other little washer pieces that fit on. Just replace them as you take them off.
Then just slip the driveline pieces back together, and reattach to the car.
Good time to replace both flex discs.

If I forgot something here, someone will chime in. Happy motoring.

Charlie

Note. I used white nail polish, no I don`t ware it .

[hangit]

I think I read somewhere on this forum that you could drive the new bearing on by using the old bearing to beat against if you don't have the 1 7/8 pipe.

John

[charmalu]

I got my pipe at a muffler shop, the guy gave it to me. only needs to be
a foot long or so. using the pipe it`s being pushed on evenly.

Charlie

[Kpmurphy]

I just replaced the carrier bearing over the weekend. I still have the same rumble noise I had before. The large 46MM nut that holds the 2 pieces together must not be very tight on my car. The 2 pieces came apart with out loosening the 46mm nut. Now I need to find a 46mm wrench to try and tighten it, and hopefully get rid of the noise.
1980 300SD

[hangit]

How about using a pipe wrench?

John

[mobetta]

a 1 1/4" pipe nipple about 10" long works good to install the bearing. you can put a cap on one end to protect the threads.

KPMurphy- maybe the half shafts?? and a channel locks will work, I beleive.

[showme]

I really appreciate the help, Charmalu (and everyone else!). That's the kindk of answer I like to get. I'm the type of person who thinks I can do about anything that needs done, as long as I have an idea of what it is I'm up against. It's help like yours that makes it easier to get in and get it done. It's also wise advice like I've gotten from others (ex: my block heater question), that keep me from getting into something I'd probably be sorry for afterwards. Thanks again, and if anyone else has anything to say about the bearing installation, I'd be very happy to hear it. Every little bit helps. Lee

[mobetta]

YOu neeed a 15mm and 17mm wrenches to get the flexdisc loose. a prybar to force it off the rear diff, and a 14or12mm?? socket and extension on the hanger itself.

I use spray paint and a bit of cardboard to mark my driveshafts. hold the cardboard lentghwise along the driveshaft, in effect masking it off right down the length, and spray, it will leave a really nice, large straight line that is almost impossible to miss-align.

[JimmyL]

Originally Posted by mobetta

I use spray paint and a bit of cardboard to mark my driveshafts. hold the cardboard lentghwise along the driveshaft, in effect masking it off right down the length, and spray, it will leave a really nice, large straight line that is almost impossible to miss-align.

That is an excellent way to mark the driveshaft. I will use that method in the future.....

[hangit]

Originally Posted by JimmyL

That is an excellent way to mark the driveshaft. I will use that method in the future.....

I hope to never have to do it again! But I will remember the technique just in case.

John