Help. Broken Diff or Axel shaft? - PeachParts Mercedes-Benz Forum

pj67coll · #1 01-15-2016, 07:39 PM

Looks like my strategy of getting to 400K miles without major incident has failed. Today at work the 240D started making a nasty banging sound from the rear. It's intermittent in that it sometimes drove for a while with no sound then the sound would appear. Sometimes it would start quietly and increase in volume, sometimes it would start real loud. It's a definite bang bang bang coming from back under the trunk and I can feel a slight vibration as it happens thru the driveshaft tunnel. My guess is either an axel shaft or the diff.

Strange thing is that its so variable. I'd have thought if it was the diff it could only be a broken gear and if so it would be permanent. If part of the axel shaft surely likewise. I mean how can such a thing be there one minute and gone the next? Cars up on ramps right now while I looked for obvious signs of trouble under there but couldn't see anything wrong. Except the driver side axel shaft is a replacement, the passenger side appears to be original and the boot is worn and possibly cracked.

If its the shaft how hard is it as a DIY? Or would it perhaps be better to just try and find a complete rear end and swap the whole thing out?

- Peter.

Ceristimo · #2 01-15-2016, 08:11 PM

Axle shaft should not be too hard. I haven't done the job myself yet, but am about to replace the shafts on my W123 in the next few weeks, and I've found several well detailed how-to's. It looks fairly straight forward.

Here is the How-To on PeachParts:
http://www.peachparts.com/shopforum/diesel-discussion/220000-w123-how-replacing-rear-axles.html

Here is another one from a blog with good pictures as well:
http://mercb-w123.blogspot.com/2013/06/canging-rear-axle-driveshaft.html

Intermittent banging though:
Are you sure it's not your drive shaft? Check the flex discs and the carrier bearing...

Also, a word of caution: I don't know if it's a valid claim, but I've read online that folks say to not mix&match between the homokinetic and annular style of rear axles. Apparently having one of each makes the differential unbalanced and can break it. Again, I don't know if the claim is valid, but it sounds plausible to me, and I thought I'd mention it. Do with it what you want. Personally, I'm planning on swapping out both rear axles for the annular ones.

pj67coll · #3 01-15-2016, 09:39 PM

Quote:

Originally Posted by Ceristimo

Axle shaft should not be too hard. I haven't done the job myself yet, but am about to replace the shafts on my W123 in the next few weeks, and I've found several well detailed how-to's. It looks fairly straight forward.

Here is the How-To on PeachParts:
http://www.peachparts.com/shopforum/diesel-discussion/220000-w123-how-replacing-rear-axles.html

Here is another one from a blog with good pictures as well:
Mercedes w123: Canging the rear axle Driveshaft

Intermittent banging though:
Are you sure it's not your drive shaft? Check the flex discs and the carrier bearing...

Also, a word of caution: I don't know if it's a valid claim, but I've read online that folks say to not mix&match between the homokinetic and annular style of rear axles. Apparently having one of each makes the differential unbalanced and can break it. Again, I don't know if the claim is valid, but it sounds plausible to me, and I thought I'd mention it. Do with it what you want. Personally, I'm planning on swapping out both rear axles for the annular ones.

Thank's for the links. I'm not certain of anything at this point. It really sounds like something turning around and hitting something. I'll have a closer look at the driveshaft tomorrow but with the time I had available to look this afternoon I didn't see anything wrong with the rear rubber driveshaft link back where it enters the diff. The noise is definitely coming from the far rear of the car.

Maybe they put a different type of half shaft on when they changed the one side and that buggered the diff

- Peter.

Carpenterman · #4 01-15-2016, 10:49 PM

Relax. It's almost certainly not the diff. I can't recall ever reading about a failed 123 differential.

It's an axle shaft. The intermittent nature of the sound is a classic symptom. It's probably the one with the likely torn boot. If it's really the original, I'd say you got pretty good service out of it.

Not a hard job to replace--no special tools other than maybe a deep socket to get the screw that holds the shaft to the hub.

Do not replace with a cheap Chinese axle. I recommend CVJ out of Denver.

CVJ Axles - CV Axles & Steering Racks for all your needs

pj67coll · #5 01-15-2016, 11:49 PM

Quote:

Originally Posted by Carpenterman

Relax. It's almost certainly not the diff. I can't recall ever reading about a failed 123 differential.

It's an axle shaft. The intermittent nature of the sound is a classic symptom. It's probably the one with the likely torn boot. If it's really the original, I'd say you got pretty good service out of it.

Not a hard job to replace--no special tools other than maybe a deep socket to get the screw that holds the shaft to the hub.

Do not replace with a cheap Chinese axle. I recommend CVJ out of Denver.

CVJ Axles - CV Axles & Steering Racks for all your needs

That makes me feel slightly better. I'll see if I can make a video of it tomorrow and upload it so it'll be clearer what I'm talking about. If it is the axle I wonder if it might be better to replace both. After all I have no idea where the replacement is from.

- Peter.

Stretch · #6 01-16-2016, 04:05 AM

Have a look at this video Peter

https://www.youtube.com/watch?v=mJr92M8hhAQ

(As said above) It is most likely an axle.

Chris W. · #7 01-16-2016, 09:13 AM

Don't overlook the driveshaft center bearing, if it has one. Or the flex joints on the drive shaft. If your rear axle shaft was completely sheared, the car would not move, assuming you have a normal, open diff without limits slip.

Rgds,
Chris W.
'95 E300D, 457K

pj67coll · #8 01-16-2016, 12:06 PM

Quote:

Originally Posted by Stretch

Have a look at this video Peter

https://www.youtube.com/watch?v=mJr92M8hhAQ

(As said above) It is most likely an axle.

I've seen that vid. I agree that it seems like it could be the axel. I don't see how a problem int eh diff could be intermittent in nature whereas in the axel I guess it could be depending on the wear point and the in and out motion of the shaft across that point.

I've been quoted almost 400 bucks to replace the axle assuming its the problem. My natural inclination is to try and do the job myself but the problem with that is I'd have to have the right equipment and I don't think I have decent enough jacks or jack stands, not to mention the larger sockets or breaker bars.

- Peter.

Stretch · #9 01-16-2016, 12:45 PM

Quote:

Originally Posted by pj67coll

I've seen that vid. I agree that it seems like it could be the axel. I don't see how a problem int eh diff could be intermittent in nature whereas in the axel I guess it could be depending on the wear point and the in and out motion of the shaft across that point.

I've been quoted almost 400 bucks to replace the axle assuming its the problem. My natural inclination is to try and do the job myself but the problem with that is I'd have to have the right equipment and I don't think I have decent enough jacks or jack stands, not to mention the larger sockets or breaker bars.

- Peter.

If you mean 400 USD to replace + the cost of the part I reckon you should consider doing the job yourself.

If you have the homokinetic axles then no big / different than bog standard sockets are needed. There's a 10mm (?) hex head bolt at the wheel hub. There's a circlip in the differential. That's it.

To lift the car I've used a combination of the wheel changing jack and jack stands before with a cheapo trolly jack. The sills / structure needs to be sound of course - but knowing you've got a problem there isn't such a bad thing in my opinion. Lifting slowly one side by a bit - jack stand - other side by a bit - jack stand - back to other side -adjust jack stand etc takes longer but you get there in the end.

You need to support the differential because the rear cover needs to come off as that's your "third" subframe mount but even sturdy blocks of wood can be used here as it doesn't carry the whole weight of the car.

pj67coll · #10 01-16-2016, 06:15 PM

Quote:

Originally Posted by Stretch

If you mean 400 USD to replace + the cost of the part I reckon you should consider doing the job yourself.

No. It's actually $380.42 all inclusive. I just don't have the cash right now. Only good thing is my truck seems to be behaving itself now so I have another vehicle to drive while this is being sorted.

- Peter.

pj67coll · #11 01-16-2016, 06:33 PM

So I took it to the local hardware store today. Had to get some drywall supplies to fix a leak in the garage. I had my cell phone ready to record the noise so I could upload it for you all to hear. Not a sound. Nothing! Quite as a mouse. Well. Quiet as a 240D I guess. What the hell? I thought the thing was going to blow apart when I drove home yesterday.

- Peter.

pj67coll · #12 01-16-2016, 07:49 PM

When I was under there this morning. I took some pictures of various components that might be relevant. This is the prop shaft connection to the transmission. Looks decent to me. It may have been replaced back in 2009 as the first maintenance record I have from the PO was dated 09 and it refers to a manual transmission flange at a cost of $100.00.

Then there's this one. Is it the center shaft bearing? Covered in grime so hard to tell its condition. But I wonder if the splines on that shaft should be so visible so far out?

A closer up shot.

This is the last coupling. Where the driveshaft joins the diff. Looks ok to me here as well.

This is the driver side axle shaft. It was replaced sometime in the past. I don't know when as the PO only had the car since 09 and there is no record of this being done under his ownership. I have all records since his ownership which is why I assume it was done prior to 2009.

This passenger side one I assume to be original.

Wider shot of the right side axle.

It doesn't look to bad but when you get up closer to the boots you see this.

I'm not actually sure that the crack is all the way thru the rubber. I thought it might just be a deep groove in it or is the shiny portion the inside of the boot showing thru?

- Peter.

Stretch · #13 01-17-2016, 01:53 AM

There's a rubber boot missing which makes these splines seem scary

Ideally you should get a boot fitted - pain in the arse though as you have to remove everything to get to it.

#####

As for the axle boot =>

That's probably a gonner.

vstech does or used to do axle re-boots for people. Ask him for a quote.

If you're down on luck and cash others have stayed off the wolves by refilling the axles with oil via a syringe and wrapping the boot with duck tape. Another trick is to swap axle on LHS with the one on the RHS - so the driving side of the spiders (part inside axle) is on the other side. Sometimes you get less clunking.

These are not ideal fixes but when needs must.

Diesel911 · #14 01-17-2016, 11:39 AM

Quote:

Originally Posted by pj67coll

I've seen that vid. I agree that it seems like it could be the axel. I don't see how a problem int eh diff could be intermittent in nature whereas in the axel I guess it could be depending on the wear point and the in and out motion of the shaft across that point.

I've been quoted almost 400 bucks to replace the axle assuming its the problem. My natural inclination is to try and do the job myself but the problem with that is I'd have to have the right equipment and I don't think I have decent enough jacks or jack stands, not to mention the larger sockets or breaker bars.

- Peter.

One of the things about DIY is that when you spend money on Tools at the end of the Job you have Tools you may need later.

You are going to need the Jack Stands at some point in time.

Letting a Mechanic do it you Money is gone and no Tools left after the job.

The Bolt that holds the Axle Shaft in place on the Hub end is not large.
That leaves the Bolts on the Differential Cover and the Nuts on the Differential Mount. None of those are abnormally large.

You will need to make sure the Differential Fill Plug can be removed. That takes a 14mm Allen Wrench or Allen Socket (on my W123). For some reason that plug can be difficult to remove.

In the Pic the the 2 Arrows to the far left of the pic point to the 2 Bolts that would need the largest Socket. I don't recall the size. Perhaps someone else can supply the Size.

Diesel911 · #15 01-17-2016, 11:52 AM

Quote:

Originally Posted by pj67coll

When I was under there this morning. I took some pictures of various components that might be relevant. This is the prop shaft connection to the transmission. Looks decent to me. It may have been replaced back in 2009 as the first maintenance record I have from the PO was dated 09 and it refers to a manual transmission flange at a cost of $100.00.

Then there's this one. Is it the center shaft bearing? Covered in grime so hard to tell its condition. But I wonder if the splines on that shaft should be so visible so far out?

A closer up shot.

This is the last coupling. Where the driveshaft joins the diff. Looks ok to me here as well.

This is the driver side axle shaft. It was replaced sometime in the past. I don't know when as the PO only had the car since 09 and there is no record of this being done under his ownership. I have all records since his ownership which is why I assume it was done prior to 2009.

This passenger side one I assume to be original.

Wider shot of the right side axle.

It doesn't look to bad but when you get up closer to the boots you see this.

I'm not actually sure that the crack is all the way thru the rubber. I thought it might just be a deep groove in it or is the shiny portion the inside of the boot showing thru?

- Peter.

You have Annular Rear Axles. If they are stock Mercedes Axles they are easy to replace the Boots on as you can take apart the end with the Bolts on it to slide the Boots over the Axle.
Annular Axle Taken apart
http://www.peachparts.com/shopforum/diesel-discussion/277503-w123-annular-style-axle-rebuild-2.html

If they are Chinese Annular Axles no one has posted anything about how to reboot them.