So my parents were driving the 300SD on I5 out of Salem when suddenly the gauges went nuts and started losing forward momentum going downhill. They pulled over and put it in and out of gear which resulted in fairly awful grinding noises. This put it at the side of the road and it had to be towed home.

I came home today to inspect. My first thought was the flex disk which is original to the car but I was able to see that the output to the transmission, where the front flex disk bolts up, had pulled out of the transmission (I could see the splines).

I then pulled the exhaust shield off so I could get a good look at the center bearing. There is a lot of play in it and it can be moved back and forth and up and down a bit.

So did the center bearing fail or is there something that holds the output to the transmission that failed? Or is there something else I'm missing?

The pictures aren't great but give me your best guess.

Attached Thumbnails

       

__________________
'84 190d 2.2 - Silver
Converted to 5-Speed
'84 190d 2.2 - Blue
Factory 5-Speed

'76 300D (W115)
Sold, found again in less auspicious circumstances

I am sure glad it was only the car which suffered damage...

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

It's been a while since I looked at one but I think there should be a nut holding the transmission end of the flex disc mount on the transmission output shaft. But if it's pulling out of the transmission, I think it also means that the big nut in the middle of the driveshaft must be loose allowing it to shorten up enough to allow the front of the driveshaft to move back.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

There is a nut holding the yoke assy in the transmission. Focus on the driveshaft. If it is as bad as you say I would recommend replacing the support bearing at least. I can't tell exactly where the play is from here but you may need to replace the universal joint (crossing bearing in paper mill speak).

__________________
Jim

I wonder if the splines where the two pieces of the drive shaft join are stripped. It may be possible if the nut is loose. It's hard to tell if anything is wrong from any of the photos.

__________________
DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

a 1 5/16( or metric =) 12 point nut holds the yoke on.

how are the engine and transmission mounts?

Transmission mount looks nearly new, the engine mounts looked ok the last time I checked...

I'll have to pull it apart and see if the bolt in the yoke is still there.

__________________
'84 190d 2.2 - Silver
Converted to 5-Speed
'84 190d 2.2 - Blue
Factory 5-Speed

'76 300D (W115)
Sold, found again in less auspicious circumstances

there's nowhere for it to go. it should be staked on to the output shaft. at the least, get a new seal for the output shaft while your there.

Bought a car several years ago with the same problem. PO was told it need a $2K trans rebuild, so I got it REAL cheap. Turns out the nut had backed off the output shaft and the output flange/drive shaft pulled out of the trans. The splines on the flange were shot, but the shaft is hardened & was ok. Get a new nut & seal, clean & inspect flange. If you need another flange try Sun Valley in Ca. They sent me one with the seal surface all machined & ready to go for $35. If it's ok, torque new nut to 75 ft lbs & be sure to peen the back of the nut into the machined recess just behind the threads on the output shaft. You MUST use a new nut. The old one will not hold if peened again. This could be what caused it to come loose. See this post for pics:
http://www.peachparts.com//shopforum/showthread.php?t=158193&highlight=johnt49

__________________
82 300SD 202K
82 300SD 233K
83 300TD 340K
82 300TD 98k euro (parts on the hoof)
85 300TD 282K
83 300TD 197K

When you say "play in the center bearing," do you mean the rubber that holds the bearing in the support, or play between the actual bearing and drive shaft? You should be able to move the rubber from side to side about
1/4 inch, but not back & forth. The actual bearing should have no play.

__________________

Don't Chrome them; polish them