my front right side shock absorber broke its lower screw lined to the lower triangle. does any one know the reason or does it happened with any one else before?

Doesn't sound common, but at 18 years old it could be stress corrosion cracking. Where is the truck driven? Can you post a picture?

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the truck run always on asphalt no off-roads. the absorbers were changed 1.5 years back (Sachs brand) I will send you picture of the fragment kept in the triangle of the screw. but if you have a picture of the original screw of the shock absorber I appreciate if you can send it to me.

Sorry, I meant what kind of climate? Did it see a lot of salt in winter?

However, if the bolt was only 1 1/2 years old, it sounds like a bad bolt. I would get an OEM replacement from the dealer, and do the other side as well to be sure..

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I am located in Lebanon, there is no salt on the roads, I have a question should the bolt fill out all the threads (to the other side) of the triangle and get out from the other side?

This sounds like the bolt is too short and not extending through the suspension bracket. Having a picture or drawing would help.

I wonder if there is also a language translation problem making description more difficult. Contact this guy, he is from Beirut, Lebanon. Please be sure to post the results.

http://www.peachparts.com/shopforum/members/jayrash.html

Here, around time 14:30, you can see the bottom bolt. Just as important, you can see the shock bottom has a piece that extends into the hole as well and fits snugly. The bolt is primarily providing a clamping force, and the shock itself carries the veritcal loads. If the bolt is torqued correctly at installation, it should "never" fail in service.

http://youtu.be/qESVvEfn7oA

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This video is for 2002/2005 model not for 1998. As u said the extended piece of absorber can not enter in the triangle since the triangles installed in my car doesnt have this feature

I can't speak to what you have on your truck, but the specified part numbers for the control arm, shock, and bolt are the same for the model years based on the EPC site. The bolt part number is N308676014002.

I also came across this thread, where someone else had a broken bolt and had to drill it out and re-tap the threads:
1998 ML320 Shocks or Struts ? - Mercedes-Benz Forum

Also note it's possible the Sachs is different than the Bilstein shown in the video. it could be there's a separate busing on the bottom vs the integral one on the Bilstein.

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