Can someone please tell me how to test for ball joint wear and replacement?

should one just replace same when the schedule says so?

What can happen if a ball joint is worn - safety?

Ps If this has been asked and answered please delete same - I did search mind you

99% of the time, ball joints are replaced for excessive play.

Just support the lower control arm & move the wheel/tire & watch for movement.

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MERCEDES Benz Master Guild Technician (6 TIMES)
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I usually put a jack under the front crossmember, then I take a crow bar and put it between the tire and the ground wiggle the wheel with the crowbar and have a assistant watch the BJ for any movement. The crowbar helps overcome the spring tension on the lower control arm. A BJ will often clunk for while before it fails totally, but it should be replaced ASAP, no point in playing Russian Roulette.

A BJ will failure will have catastrophic results. The bottom of the wheel will no longer be attached to the suspension, so you'll have total loss of control . No biggy in your driveway, but not fun on the highway.

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I choose to be happy, even when the Mercedes is being awkward, lol

Thank you so much M.B.Doc and Smiffy6four for responding and helping
I really appreciate it.
I did some more search based on the info you guys provided and I hope to get more specific info to the 2002 ML 320 I have, as I am no expert like you guys and will have to follow them to the tee in a step by step monkey see monkey do fashion


Step 1 Secure the vehicle with the emergency brake.

Step 2 Chock the rear wheels of the vehicle. Use approved chocks for safety. They wedge beneath the tires keeping the vehicle from accidentally rolling out from under the jack.

Step 3 Place the jack under the lower control arm, as close to the ball joint as possible. This will create pressure against the spring. This is important since the wheels are off the ground, a load needs to be pressuring the ball joint.

Step 4 Jack the vehicle up just high enough to be able to firmly grab under the tire on that side only. The tire shouldn't move because the emergency brake is set.

Step 5 Grab the tire at the top and bottom and rock it back and forth, giving it a good tug each time. Bad wheel bearings will reveal play in the rocking movement.

Step 6 Use a dial indicator to measure bad ball joint wear. Ball joints should be replaced in pairs whether they're both bad or not.

Sourced from ehow.com

Step # 6 is bullcrap...never replace a good part! Only replace badly worn parts.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

That gave me a serious chuckle. I use cobblestones, have yet to fail me. Plus, they are more pleasing to the eye, and free.

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