[mercbentz]

As a follow/close up of my end of the project, which started with replacing the "after CAT" O2 sensors:

Finally, the car is back on the road, with the MIL(CEL) OFF and so far the O2 sensors tests cycles completing without any errors. The car seems to be running very well, better than I can remember.

As final conclusions, none of the old O2 sensors could be removed without being damaged, so finally, there were 4 (four) new O2 sensors installed. The damaged O2 sensors left quite a bit of metal garbage inside the sockets' threads, which had to be cleaned carefully with a "thread chaser" and a M18x1.5 "tap" - recall some "warning" posts on this topic, and I understand a lot better their meaning. For removing the CAT/exhaust, old bolts&nuts had to be cut, or drilled.

The posts on this thread, and others related to the type of problem, were very helpful: thanks again!

 

[dordway]

I recently replaced my cat (actually removed, welded, then re-installed) and had a few things to add to this post which may help others out.
My car is a MY2001 ML320. I read many posts about doing this work. Most of it results in someone posting about the recall. Unfortunately my car is outside the VIN range affected by the recall. But the failure type was exactly the same.

Here is what I can add to the post.
Torsion bar removal is fairly easy. Before starting, measure the lever arm position thru the hole next to the screw which pre-loads the torsion bar. Next, unscrew the bolt. It takes about 80 turns to release it and it does not spring apart at the end. Socket size is 18mm. There is a rubber boot on the screw which protects it from getting rusty. Re-installing this boot is a pain, but I have a trick for that.
There is no need to remove the lever arm at the back of the torsion bar to get the bar out.
At the front of the bar, make an alignment mark between the hex sleeve, the torsion bar, and the pivot for the lower a-arm. This will help you get things re-aligned later. It may be impossible to get it wrong, but it's hard to tell when you in the middle of it.
Undo the 2 bolts which hold the a-arm pivot in place and swing it open. My ML did not have bolt which goes thru the hex sleeve as shown in the pdf file. I could slide the sleeve back by hand and it was released from the a-arm. There was lots of white grease on these parts and I re-lubed them at re-assembly. If you have to use force, the only way to do it is to used a chisel on the outside surface of the hex sleeve and strike it with a hammer angled toward the rear of the vehicle. The torsion bar passes thru a steel hoop attached to the car near the transmission cross member. If you have gotten this far you will realize that is a good thing since it balances the torsion bar perfectly. This helps re-assembly, too.
Slide the hex sleeve off the end of the torsion bar. Then slide the bar toward the rear of the vehicle and it's out.
You need to remove the steel hoop I mentioned before and it's a pain since the nuts are on top. When I re-installed this hoop I flipped the fasteners over so the nuts are on the bottom.
The get the cat out of the car I found I had to remove both O2 sensors and loosen the clamps to both pipes going into the rear muffler. The bolts at the exhaust manifold are a pain to get at. Wobble extensions help here. Finally I could wiggle the cat out.

Re-assembly... Reconnecting the bolts at the exhaust manifold was a pain in the ass. If I had a 3rd arm it would be easier. I had to hold the flange in place with one arm, then maneuver the bolt balanced on then end of wobble extensions up to the hole. The bolt kept falling off, though. I tried holding it there with grease, but it still get off. Finally, I tapped the bolt into a 1/2inch 12 point socket and it stayed on well enough to get the job done. Once you have one bolt in, the 2nd one is a piece of cake.

Now here is what I found works for reinstalling the torsion bar. Reassembly is exactly the reverse of disassembly with the exception of the rubber boot for the Pre-loading screw. Here is what I did... Force the boot onto the captive nut in the torsion bar lever arm. Screw the bolt into the nut so it sticks into the boot by about an inch. Compress the boot so it attached onto the end of the screw. Then install the torsion bar at the front, being careful to keep the boot in place. Next install the bracket which holds the bar in at the back of the torsion bar and the shim but leave it angle down enough to get the pre-load bolt out. I used a piece of wood to hold this in place. Reach over the frame of the car from the front and you should feel the top of that boot. Hold it to prevent it from rotating as you unscrew the bolt. It should rest against the car body. Keep holding it to prevent it from buckling. Now push the bracket for the torsion bar up and feed the pre-load screw thru it and into the captive nut on the torsion bar. When you get it in far enough you will feel the end of that screw engaging into the boot you have been holding. Continue tightening the bolt until the arm is back in the correct position which you measured in the beginning. I held the boot in place as I was turning the crew because it took me so long to figure out how to install it properly. I would not want to work on a car which this bolt was rusty on, so I felt it was important to get the boot back on.
Sorry for no pics.

 

[ddacombe]

Thankyou mercbentz for your '11-12-2009, 05:07 PM' and '11-13-2009, 01:41 PM' posts.
This was a huge help since I too have the modified sleeve which has no bolt.
I didnt have much luck with the slide hammer but used the following method, hope this can help someone;
1/ Jacked the car up off the ground
2/ Placed jack stands under the transmission
3/ Removed transmission crossmember
4/ Measured depth in hole on Counterplate 16b
5/ Removed bolt 16c
6/ Remove metal tab that holds Counterplate in place, then remove Counterplate 16b
7/ Removed the two bolts on bracket (BR), where the cylinder meets the sleeve and torsion bar
8/ Removed the two bolts that hold the metal collar (168) in place. I had to apply MAPP gas to these 5/8 inch bolts to free them.
9/ Once that is all out the way, the torsion bar can be pulled down so the clamping lever 16d is below its housing. I then used a piece of plywood to cover the housing and prevent the clamping level going back into place.
10/ With a 5lb hammer, I then hit the clamping lever a number of times in the direction shown by the green arrow until the bar came out.
Thanks again.

 

[mercbentz]

Thankyou mercbentz for your '11-12-2009, 05:07 PM' and '11-13-2009, 01:41 PM' posts.
This was a huge help since I too have the modified sleeve which has no bolt.
...
Thanks again.

You're very welcome. Glad that was useful.

Hope the experience you've shared will be helpful in the future to other members.

mercbentz