w123 rear suspension CRACK? EEK!!!

I had my 1983 300D Turbodiesel on car ramps today, to drain the fuel tank and replace some hoses, and much to my horror, noticed that a rear suspension component, whose name I'm not certain of, has a crack. How can this have possibly happened??? What's the proper fix? How would I go about it, and what would I need, etc. The car has about 200,000 miles on it and wasn't in an accident ever. I'm shocked and quite worried that this is a "big project..." Here's some pix... ANY advice would be most appreciated. Doesn't seem like a common problem at all...

NSA - Hazleton, Pennsylvania

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Body and Interior Specific Aid

Chassis Model Number

W123

idea...

Would it be a bad idea to just go to a chain muffler shop and have them weld over the crack? The crack seemed to spread a couple of thousandths of an inch while it was under the stress of being on one engine ramp. (Was that a bad idea???) I really am shocked. These cars are so durable, the last thing I imagined having a problem with is this suspension part. NSA - Hazleton, Pennsylvania

Welding is not a good idea

Failures of the 123 rear trailing arms like this are more common than you think. Failure is most often caused by rust usually from the inside out. Especially if the car has driven in heavy rain for many years or been subject to road salt even for a short time. Welding might only be a temporary and possibly dangerous fix. I have only seen a few failures that were caused by fatigue only. The only way to safely and permanently repair the problem is the replace the trailing arm with a good used one of a non rust area of the country.

We get requests for these quite often and currently have a couple used in stock. Just type 123 trailing arm in the search box.

Okay, so I'm a perfectionist. Now what?

Okay, okay. Corrosion makes sense. I think that the left rear "trailing arm" failed from the stress of being put on a car ramp, via a lift. (that side alone... - 1 ramp - the other 3 wheels on the ground mostly anyway...) Like I said, maybe that was a bad idea, but another side of me says that if the arm can't handle that, it's dangerous anyway... First off: WAS THAT A BAD IDEA??? Second: Since this car is most definitely a "keeper" and we are in a salty road area, would the "PROPER" way to handle this situation involve assuming that both rear trailing arms are comprimised, even though the other side is crack free? That's what I'm thinking, but I'd like a second to that motion... Actually, since it's a keeper and it's to be assumed that another 200,000 miles in a salt belt may further damage the newly replaced ones, so perhaps, pre-emptively the best way would be to dismantle two mercedessourced rear trailing arms, get them blasted and powder coated before installation??? Is this overkill or sensible for a bona-fide keeper-forever type car? Also, with what's involved with replacing both, what other parts should I replace "while I'm in there???" Shocks? Springs? What bushings or lines, etc. Bearings???? We love the car. It IS most definitely a keeper and I don't want to take the cheap/easy way out. I want everything tip-top. So, with that. Any advice would be most appreciated. I'm anxious to start the rebuild or whatever you'd call this sort of project. All the best! NSA - Hazleton, Pennsylvania

Rear Trailing Arm Help

Get a new trailing arm and paint it with "Miracle Paint". I know it sounds like a commercial, but imagine dipping the part in an epoxy. It works! Keeps the salt off my car when I go to Minnesota every winter. I just hose the entire car out with it on a lift from the underside. If you can get another trailing arm and paint all sides of it, you can bet it will outlast the rest of the car. Call me crazy, cracked, etc., but if it can seal mufflers better than muffler tape, and fix a cracked radiator at the seams, well - you get the picture. Benz be Best! Stickman-Dothan,Alabama