240d 123.005 manual transmission bearing noise
 

Edit: 716.005 3 piece iron case transmission

Hi, I recently purchased a 78 240d with 178k, I probably overpaid at $4900, but I've been looking for one for almost 6 months and was getting frustrated. The car has lots of problems. I want to make it my daily driver, but one of the biggest concerns is the transmission has an awful bearing noise, so I need to pull it and fix it. I can't find any rebuild kits for sale, so I was just wondering if anyone knew which bearings commonly fail? I was hoping to get all the parts I need before pulling the transmission. It makes noise when in neutral with the clutch engaged and when in gear driving down the road. I know it is not the throw out bearing based on when the noise is present, and because the previous ower just had the clutch replaced. I think they split the driveshaft without marking it, because now its out of balance.... I'm going to end up spending a fortune on this thing.

Well, a 78 Mercedes is in the end just another old car. The longevity that was built into many of the Mercedes components is long past due for failures.

You did not mention checking the transmission lube level or changing that. Low lube levels can cause transmission bearing noise.

You need to look on the internet and fine out how to differentiate tween a throw out bearing noise, the details of which cannot remember accepting the nose changes when you step on the clutch and an input shaft bearing noise.

The Haynes W123 manual has a section on the manual transmissions. Don't get a new one they have used ones on eBay.

Generic manual transmission bearing issue in order of frequency. The throw out bearing, the pilot and input shaft bearing because they work together and the output shaft bearing.

Attributed to someone in Germany: If you own an old Mercedes, you are either rich or a mechanic.

Yes, it has fresh redline oil in it and it is full. Throw out bearing and pilot bearing would be when clutch pedal is depressed. I'll probably just order the input shaft bearing and seals, and see if I get lucky. I was just wondering if there was a common failure . This is my first classic Mercedes.

I used to daily drive a 73 bmw 2002 before It got hit by a drunk driver in the middle of the night, sitting in my driveway. I had the body stripped, completely restored and painted, but I haven't put it back together. The box full of engine parts got filled with water, thanks to a leaking roof, and I haven't been motivated to buy all the parts again.. Now Im driving a 74 Triumph TR6 but I need a second car to drive while I rebuild the engine, so I got the Mercedes. I have a problem...

Oh it's a 716.005, not a 123.005. it's the 3 piece iron case transmission.

Agree, noise at idle with no pressure is most likely the input bearing; but, the throwout forks can wear badly and the throwout bearing may be flopping around. Does it sound like a bad bearing or more like something loose?

The Benz manuals of that era were very robust and didn't have frequent internal problems. Problems were usually limited to clutch issues, worn shifter bushings and improperly adjusted shift linkage.

Putting the time into all new shift bushings, cleaning, lubing and adjusting the shifter does wonders.

Keep us posted on what you find, if it is the input bearing hopefully it can be replaced without a full transmission teardown. A rebuild is $$$ in parts, look for a good used unit if necessary.

Ya it sounds like a bearding to me. I think this car was sitting for a very long time. The fuel tank was rusted completely. Looked like a Martian cave inside. I pulled a used tank from a 300d at at a junk yard for $35 that looks perfect inside, other than a little algee. The bearing might have sat dry for so long it rusted?

The shifter feels great. Just needs some fresh grease. Most of the plastic are rubber parts look new. It must have been in a garage most it's life.


I have the Mercedes w123 factory manuals and om616 manual. Is the Mercedes manual for the manual transmissions any good or did you recommend the haynes manual because it is better?

Before you tear down the transmission…
-is your driveshaft bearing good? The rubber discs on it?
-how are the pedal hydraulics? Pedal feels nice and firm?

I’m sure you’ve checked these but just in case.

Well I got the transmission out and got the input shaft bearing out. It makes noise, but so does the rest of the box. I'm guessing the needle bearings are bad too and have chewed up the shafts. I haven't torn it down that far yet. I think I'm just going to get a used box. not sure what happened. Maybe the oil was never changed untill the previous owner replaced the clutch at 175k.

The pilot being can affect the input shaft bearing.

None of the official Mercedes service manual books or the CDs of those I have anything about taking transmissions apart other than fitter change.

People have said that there are official Mercedes transmission manuals, but they are in German.

The Los Angeles public library system used to have a Official manual transmission book. That was like 15 years ago.

The Haynes W123 manual that I bought used is the only one easily available that has exploded views and so on. Not a lot.

One of the few companies that has info on Mercedes auto trans is ASTG.

I think they also have the manual transmissions. At one time there was thin books but now I think they are on CD of DVD.

This site claims to have downloadable manuals.

https://mbmanuals.com/transmissions/mb716g76trans.htm

There is an English Company. Bently Manuals that has an expensive manual on gasser W123s. I have no idea what is in that manual.


I will add stuff as I find stuff.

https://shopservicemanual.com/product/service-manual-mercedes-716-transmission-up-to-2020-incl

It must exist, I have one hehe.