Help Needed W123 Axles
 

I'm trying to get the diff fill plug out before draining it. It is really not wanting to move. I don't want to break anything if it can be avoided. Are there any tricks to getting this out? Would applying heat to the diff cover help? can I use a small sledge on the breaker bar? Any suggestions are greatly appreciated. This looks liek the hardest part of the whole damn job.

Thanks Much.

Just in case. I am trying to turn it CCW (lefty loosey) as looking at it. Tool in plug, pressing downwards and towards the right of the car. I'm on my back at the left side. I Know this sounds stupid but .....

No don't worry it doesn't sound stupid.
Try tapping the plug a little and you could try using a breaker bar of some sort. Those plugs do get tight for some reason and it's possible that your plug may have never been removed since it left the factory.

There tends to be some corrosion issue with those differential plugs - they really lock up tight.

I had to use both legs on a breaker bar to get most of mine loose the first time. Going back in, don't crank down so hard on it yourself.

A little heat won't hurt (but might not help that much either). A few taps on the breaker bar with a sledge shouldn't hurt either.

They're just really tight for some reason.

Ken300D

Ok,,, I would not use any heat... just on principle...
Do you own any little jacks (scissor type maybe).. .perhaps for other cars... which you could put between the breaker bar and the car......? You might need to put a piece of wood above it... to push against... but might as well use mechanical advantage... once your arm power is not enough....

Why not just use an impact gun?;)

Unfortunately the tool I'm using is from my 58 ponton and I'm inclined to not get too crazy with banging it and the jack thing. I'm doing my ebay search for a damn tool since noplace around here had anything. I used the jack trick to removed badly cross-threaded caliper bolts on one of my other cars and that's what I want to try for this thing. It probably was last tightend in 1983. Makes me understand the new axle design a little better. Thanks for the suggestions.

lietuviai
That was exactly what I was thinking of. While shopping Sears for the part (which they didn't have) I was going to buy a damn compressor and some monster tools too while I was at it. Getting too damn old for this on the back, leg bustin' crap just to take out a couple a bolts. :-)

Rmmagow, that's what I sometimes think about doing as well but I was offering the idea purely in fun. I always try as much as I can before resorting to a bigger tool. I don't own any impact tools simply because I know I would break whatever I would use them on. Interestingly enough, it seems that nearly all the differential plugs I've had trouble with were ones on alloy cases. I should have checked my differential last week when I had my 300D on jack stands. I think if I were to check everything under my car that were to come to mind, my car would stay on those jack stands forever.:eek:

Here is one answer
 

" I always try as much as I can before resorting to a bigger tool"
Me Too.

I already had my car up on ramps.... flushing the fuel tank.... so when I saw this post I figured I would go out and check my plugs...
Very Tight fill plug.... drain plug just right...

So I got the Mercedes tool with the 14 mm socket and the curved handle... ( very thin handle )... and hit it with a 3 foot 2x4.... then I used a 6 lb sledge hammer in a slide hammer manner... with the handle out front... but for both there was too much give in the tool...
So this is what I came up with... and it worked like a charm....
I took the wrench and placed it pointing down and hooked a comealong to the stock jack placed in the jack hole...

second...

Go to Orchard Supply or some hardware store. In the Industrial section, u can buy a 9/16 ( take it to the car and check for a fit)allen wrench for about $5.00.

Then get a persuasion bar ( piece of metal pipe anout 1.5 - 2 ft long). Spray some WD40 or some other rust eater and let it sit for sometime.

Plug in the allen wrench and put the other end into the persuasion bar. That should do the trick.

No need for overkill!

I think it is a 14 mm hex head that is needed.... sure would hate to round out a socket head plug... I know how to fix it when that happens.. but it is better to avoid rounding it out...better to use the proper size....

leathermang
That looks good!! I just ordered the tool from Samstag sales and will be trying this next work period. This 300D has been sitting all winter waiting for the damn axle job to get done. It's the good one, 30+ mpg so I'm anxious to get it back rolling. My other one, a CD only gets about 25 mpg or so. Course, after sitting so long I've got an algaefied tank of gook but some good diesel and algaecide should fix it.

I let the indy do this job for all of the aforementioned reasons. When the 126 is up on the lift, he uses the proper socket with hex bit and then applies torque with a three foot breaker bar. He probably leans into it with at least 100 lb. thereby requiring 300 ft.lb. to break it loose.

Takes him 5 minutes to pull the plug, ten minutes to drain the oil, and another 5 minutes to fill it back up. Worth the $30. any day not to have to fight with it.

I like slow/controlled application of force when I can accomplish it..... this really worked just right....

$30 will buy a comealong...... with some left over... then you have it for all sorts of other things.... This is sort of a DIY forum... not a " I took it to the mechanic" forum.... :D
More tools= better life

WD40- Waist of time
 

In the paste WD40 was the only thing out there but now there are much better penetrants to use. PB-Blaster is the one most recomended these days by heavy duty backyard mechanics.

I would not waste my time or penetrant on it... just get enough force to loosen it.... it is a deep plug....

Autozone has 1/2" drive Allen sockets. I got the right one, put in on my trusty breaker bar, got the car on ramps, steadied the bar with one foot and then kicked it with the other. Broke loose on the first shot. Rmmagow, if you want to borrow the tool you are welcome to it. RT

This thread brought back a few memories :eek:
We've had many that were so stubborn that a four foot pipe was used on a half inch drive Snap On breaker bar. I weigh 180 pounds and I've still had to ask our shop owner to lend some of his strength and 300 pound body weight before they broke loose. You can see the bar bend but none ever broke before the plug loosened.
Using a one inch drive impact might do it.
Only once, when the 14 mm drive rounded out, did we resort to the pneumatic hammer with a chisel bit to "entice" the filler plug CCW out.
30 pounds of torque is plenty to hold the plug in.
Nice piece of engineering with the come along Leather. Those things are sure handy.
I have the feeling that some mechanics are blowing the plugs back in with an impact tool.

OK, Greg, I'll shut up next time. Maybe, I'll even do it myself.:D

If you decide to do it yourself.... and need any advise... just hollar at us....

RT,
Thanks for the offer. Hopefully I'll be OK with the new tools coming in. I needed a come-along anyway to drag a garden shed a few feet. So far I don't really have an "indy" for my MB's and short of fixing the A/C I probably won't. The car is making so much noise just moving it around the yard I think the axle is ready to break altogether anyway so I feel better doing it myself.
I did undo the wheel end of the axles and both sides moved easily so that side'll be OK. Even got a pair of new rotors to put on, a pair I got off E-bay just cause they were cheap. Should be fixed within two weeks barring too much over-time at work :-(

When I changed mine a few years back, the threads came right out with the plug, LOL. (Although I wasn't laughing at the time...) Looked as though it had never been done.

I put on a used diff cover, and threw a little anti-seize on the threads...making sure not to tighten it too much.

For a stuck one, and in retrospect for myself, I think leathermang's method is the best - a slow, controlled force works far better than yanking around on a b-bar, otherwise you may risk doing what I did. ;)

If you have a Grainger near you they carry the Proto brand 14MM hex with 1/2" drive. I put a breaker bar on it with pipe extension. I think you can order a magnetic drain plug from a '70 era mb manual trans for $12.00 from the dealer. One of the more userful and affordable items from a dealer! Hate to think what that Samstag Sales item cost. Remember to put some aniti-seize on it and torque it properly when it goes back in.

I remember trying to the plug outta my 126. 14mm allen socket, 18'' breaker bar, section of pipe on that. Put so much torque on it I thought I was gonna turn the car over! But the plug came out clean. And yeah, this would have been a whole lot easier with the car up on a lift, 'course then I might have twisted it right off the lift.

With doing the axles you have to remove that plate anyway. On one car I think I broke it loose on the car with enough force with a 25" breaker bar. On a different w123 I just took the whole plate off, stuck it in the vise securely, heated it with a propane torch, used the 25" breaker bar on it. It seemed a bit easier after heating the surrounding area a little bit, but with just a propane torch there wasn't that much risk.

On the topic of magnets I have a transfer case in my talon which the oil looked horrible after 6k miles so I figure I'd add a magnet. I bought enough to do both my cars on each drain plug or reservoir. Well after 6k miles on the new oil it still looks pretty clean. I have magnets on the tranny pan, engine pan, and rear differential on the mercedes now. Once you open up the rear differential you'll see how valueable a magnet like this could have been years ago.... Which reminds me, its about time for me to drain out my mobil 1 75w90 and put some redline 75w90 in there. :)

"this would have been a whole lot easier with the car up on a lift, 'course then I might have twisted it right off the lift."

My car was just up on some of those plastic ramps available now... so I was on laying out flat when doing this... One would need to be much less thick than I to do this without getting the car up some....
If it had been up on an actual lift I have a four foot cheater bar which would have been faster than going and getting the comealong and the jack for anchoring...
A warning to those who have not done this type stuff.... it is very hard to hold an object in a vise and apply this much force to it without either warping or breaking it.... if possible get both plugs loose while the force is evenly applied by the bolts holding it to the differential...

Second Source for Wrench
 

NAPA has the correct allen wrench for something like $8.00. Not as fancy as Greg's ...just a bent piece of heat-treated hex stock.

I thought mine was just the tool that came with the car.... not TOO ' fancy'.....
It fits the engine drain, the trans fill and drain, and the fill and drain on the differential.... and I assume, although I have not gotten to it yet... that the bend is for reacing the trans plug....
and why have I not gotten to the trans plugs since I already have the redline to switch it out ? Things like in this picture keep getting in my way....

Hey, I saw those berries last year!

The plugs on my diff came out with the AutoZone tool, a breaker bar, and a 6 foot aircraft aluminum pipe. That's just about the handiest tool ever.

Greg,

Very nice looking berries. I can understand how, with something like that in your way, getting that transmission fluid changed is being put on the rear burner.

I have done this with a 14mm Allen wrench I bought from Snap-On in about 1975. As I remember it was more expensive than any MB part I had purchased yet, so I still have it.

I typically use a mallet and the wrench, and tap firmly and repeatedly to loosen the plugs and drive them about half a turn before I can turn them the rest of the way by hand. I assumed the factory guy overtightened them the first time, and was careful not to pound them back in. But it makes no difference. I think one is a pipe plug and the other has an aluminum seal ring (meaning the drain and fill plugs). Both are not really good designs for ensuring they will come out easy. But, maybe that was the intent, to make them stay put even if they are not put in to a precise torque.

Like I said, I have done this literally dozens of times and not had any problems using a mallet to convince the plug to come out. Jim

Jim, I tried the six pound sledge first....but it was not budging...anyway... this could give people ideas about other items in their life needing a little extra power....