07 S550: front axle boot leak?

[kevm14]

Found all the grease splatter during a routine inspection (oil change).

I thought at first that it might be a diff axle seal. So I did the diff fluid again (see other thread). Closer inspection of the boot suggests that the grease MAY have flown out from this weird seam that is right next to the big boot clamp. The driver's side has the same seam but is dry. I thought maybe it was sliced from the boot clamp somehow but I am not sure about that theory. The boot otherwise looks to be in great shape. The splatter really does seem consistent with a boot leak. The pass side engine mount is above this area but I saw zero evidence of it originating from that high.

So what are my options? Three really. Four if you count ignoring it.

1) Replace the boot. A Febi Bilstein boot kit and a clamp pliers runs about $64 at FCP Euro. https://www.fcpeuro.com/products/merced ... 85#fitment
Apparently it also fits my E63.

2) Replace the axle with OEM. https://www.mercedesbenzpartsshop.com/v ... and-joints
Looks like it is $750 plus core. Yikes. Let's stay away from this option.

3) Replace the axle with aftermarket. Check out the Rockauto listings.

That is considerably cheaper than even the STS axle I got on Rockauto. In fact, these prices are slightly cheaper than an 07 Camry!!
Unfortunately FCP Euro aftermarket options are just as much as Mercedes. So I definitely wouldn't do that.

I choose #1. Going to attempt it. Hopefully pulling the axle is easy and only requires disconnecting the lower shock mount to swing stuff lower. I MAY have to disconnect some ball joints in which case I may need a better tool for that. My rationale is I get to keep the premium factory axle. If I screw something up, I guess I'll be forced to buy an aftermarket one.

Actually there is another option besides ignoring. Junkyard/eBay.

[kevm14]

Some forum research suggests this is actually somewhat common. I suppose that means it will eventually happen to the driver's side.

[kevm14]

Ended up writing it up with pictures on the MB forum. I'll link my posts here: https://mbworld.org/forums/s-class-w221 ... ost8840813

96k, exact same mileage as the oil change because I didn't drive it for a week.

The one thing I screwed up is I put the joint together with excess air pressure, meaning I didn't collapse the joint and burp the air from the boot. So now when on the car, the boot is like swollen and actually hitting the small clamp crimp, which will probably wear a hole in it.

So my current plan is to procure another small clamp, cut it off the axle (while on the car), somehow stick something gently under the boot to burp the air out, and then re-clamp it. I THINK I can access it through the control arms. I probably don't even have to remove the wheel. Actually I wonder if I could do it on ramps rather than on the Quick Jacks. Yeah I think this is definitely a good idea.

The other thought I had is I could just poke/drill a hole in my brand new boot, squeeze the excess air out, and seal it back up with some ultra black RTV. While that might actually work I can't bring myself to do it.

I did make a bead on the driver's side inner boot, both on the big and small end. It may buy me a few extra years but it did look aged upon close inspection.

[kevm14]

Looks like the small clamp is A0069975990. I have to pick up some cabin filters and wipers at the dealer anyway so I'll just get a clamp. Maybe I can do this today and be done with this project.

But of course they are closed on labor day.

[kevm14]

I ground the clamp off and tried to bolt the boot back. It worked but by the time I got the new clamp on, and turned the axle, it folded over on itself again. I assume the boot just got too stretched and now has a memory. Wonderful. So that was....pointless.

This is the "before," the problem I was trying to fix. The clamp would presumably wear a hole in the boot, leading to axle failure, the exact problem I was trying to avoid by replacing the torn boot in the first place.

I guess this is what I have now?

I will just have to check the boot for wear right where that clamp crimp is. I don't imagine it will last too long. It will need this job repeated and I will have to be careful to burp all the excess air from the boot before I clamp it. I wonder if an OEM boot would also be better. And if I do it again I guess I can use the correct amount of grease (140g versus the 120g I used). It's not that difficult of a job. It just sucks I will have to do it again at some point.

[kevm14]

Just some planning for the future. Using my EPC, here are some part numbers:

Inner boot, $10: https://www.mercedesbenzpartsshop.com/o ... 1337008502
Small clamp, $1: https://www.mercedesbenzpartsshop.com/o ... e-69975990
Large inner clamp, $5: https://www.mercedesbenzpartsshop.com/o ... d-89976590
Axle bolt, $14: https://www.mercedesbenzpartsshop.com/o ... lt-9907503

Can't find a P/N for the grease but I guess I'll see if they have a 140g tube.

Cheap to re-do, just some labor.