98' W210 E300TD Front end clunk
 

Hi folks,

I'm pretty sure I have read every thread on the internet on this topic. My '98 has a clunking noise in the front end, most notable at low speeds. Its very uncivilized, very un-Benz:)

114k miles on the chassis. Back in April, I replaced lower control arms, shocks, lower ball joints, sway bar end links, sway bar bushings. Parts were QE quality, mostly Lemforder branded. Shocks were OE quality Bilstein Touring. It was gloriously smooth and quiet immediately after...now several months later, crashing over bumps again. Have put the car up on the lift 2x now and checked everything I touched. Nothing is noticeably loose, everything appears tight and proper. I did note a bit of front wheel bearing play and snugged them up thinking that could be the problem...no change.

The only things I didn't change are tie rod ends and upper control arms. I've jostled these bits around and put the pry bar on them to see if there is play and have detected nothing.

What am I missing? Any ideas?

Check the sway bar bushing brackets for loose bolts. Put a tool on them and feel for proper torque. After rebuilding my car's suspension those bolts would come loose which produced some clunking until I used thread locker on them. No trouble since.

Make sure the top fastener on the strut is not loose. I had one that I was scratching my head on and found the top fastener on the strut loose.

thanks folks...couple of good ideas thus far.

pretty sure I checked the sway bar bushing bracket bolts...put a wrench on them, at least some of them. Possible some of those bolts are blocked by the transmission undertray which I definitely didn't remove when I checked things out. Will look again.

I have not checked the shock top nuts. I recall torquing those suckers good when I did the install, but its worth a look.

bumping this thread to the top. My noise is getting worse. Now 120k miles. So bad at this point that I have parked the car. Since last posting, replaced motor mounts, trans mount, and tie rod ends. Have double and triple checked all the relevant fasteners in the front end. The bang/rattle is so prominent that it should be something obviously loose, only its not obvious at all. I have a lift in my garage and have inspected the car now at least a dozen times.

I have a friend who runs a shop and he's going to bring his chassis ear tool home so we can find the culprit.

meanwhile if any other ideas are out there, please post 'em up.

Ive encountered noise caused by the upper arm on a W210 and W140.

Wasnt obvious at the time but both times those turned out to be the problem.

Upper control arms?

guarantee it’s upper control arms. You won’t feel the play in the ball joints by shaking it down, but by watching the control arm itself move up and down.

I need to go thru this on my 98 E300 and my 01 E320. Both have clunking with the 01 being worse. I have not done anything yet.

This might be out in left field, but have you checked the front spring perches?? They are buried under the factory rubberized coating, and even if the coating is intact and looks good, they can be rusting underneath. My 96 E300D made a sound like I was running over a tree branch, and when I parked the car overnight, I woke up the next morning, and the front passenger side front fender was resting on top of the tire. The entire passenger side of the engine compartment along with the spring perch was rusted, and failed. Two weeks prior to this incident, I had the car up on a lift to have the tires rotated, and I made a special inspection of both spring perches, and they both appeared to be fine with the factory coating still in place. Apparently it rusted from within the metal panels and could not be seen during a normal inspection. Good luck!!!!

Not left field at all. I was concerned the noise could be failing perches. Checked them probably 10x now. The car has accumulated an additional 6k miles from the time of my first post until today...all the while making the noise, but nothing to indicate the perches are to blame. For context, that's 6k miles of some of the most overworked, bombed out, crappy infrastructure in the country...I'm talking about NYC metro-zone.

Installed new upper control arm yesterday. Test drive scheduled for this evening. Will see if that's the noise. Can't say I noted any distinct play/looseness in the old part I removed.

Test drive results are in: when you've replaced everything else, the noise is the one thing you didn't replace ----> upper control arm!

Honestly there is nothing that would indicate play when I disassembled and removed the old part. Just glad to have it fixed...sounded like a wheel or brake caliper was about to fall off!!

Have to do passenger side now, then go for an alignment.

When mine made such a noise, even going SLOWLY over a speed bump, it turned out to be BOTH coil springs were broken

When mine did a thumping which would go away as I slowed down, it was a shock.

Well...I thought the upper control arm had fixed it after a test loop across some local potholes, but its still crash/banging like something is going to fall off.

I haven’t the foggiest f-in clue what it could be. At this point I am suspecting it could be some of the new parts I installed over the last year have failed already.

I’m thinking of swapping front shocks from left to right, to see if the ugly noise switches sides, which would indicate the shock is bad.

Had the car up again for front rotors and pads and took a close look at the springs, which don’t appear to be broken.

now 124k miles, and still making ugly noises. Additional steps taken to quiet the demon = replace hub, replace inner tie rod. At this point, EVERYTHING has been replaced within the last 15k miles.

I still need to swap the front shocks side to side to see if I got a bad Bilstein. Possibly one of the new ball joints I installed took an early dump?

Only other idea raised by a friend is the lower control arm bolts themselves...if there were too much play between the bolt and the bushing perhaps it could create the noise?

Yes, do that. I just replaced all my shocks (97 E300D) with Sachs brand and the right front sounds like a coffee can of bolts over each bump. I'm going to back off and re-torque the top nuts tonight. If that doesn't work, I'll have to check the bottom.

Check radiator , I believe it just sits on two pins and has those clamps at the top to hold it down, check intercooler and any air con fittings and any electric fans to see if they can move in any direction.
Is the alarm siren behind the plastic inner arch on these .. could be loose ?.

Victory at last!
 

So it's been almost 1.5 years, and 15k miles I've been living with the death clunk on this car, and it's been making me crazy the entire time.

Since my last update, I replaced front springs (not broken, but figured why not?), replaced driver side ball joint (2nd time in 20K miles), and swapped front shocks side to side (to rule out a bad one). No change, the noise persisted. One interesting observation though, each time I serviced the car, and had the spring compressed, the noise would disappear for 2 days or so (about 140 miles of commuting) then reappear.

Eureka moment last weekend. I took a gearhead buddy for a spin in the car (who I have been discussing this suspension noise issue with since the beginning of this saga). He heard the noise, even felt it through the chassis, and agreed it sounded like it came from the shock itself. We popped the hood, turned the wheel to get visual access to the front suspension, then he jumped up and down on the front crossmember while I watched the suspension work. I heard a faint click/knock, pinpointed the source at the bottom shock eye, where it attaches to the lower control arm. I could see a tiny bit of slop in that joint.

That's when I connected the dots - When I installed these new shocks, for reasons I can't recall now almost 2 years later, I reused the bottom bolt instead of the new one that came with the shock kit. I only re-used the bottom bolt on the driver side, used the new one on the passenger side. I think the passenger side one was stubborn to remove and the hex head got boogered up. I supposed my thinking was "if it ain't broke, why fix it". Anyway, the bolt that came with the shock kit was just a tiny bit bigger than the old one, about 0.1mm according to my vernier caliper. Using the old bolt with the new shock obviously created a larger clearance and this was my stupid dang noise the entire time!!

Lesson learned: when they give you new hardware with a part, you use it even when the old hardware is perfectly serviceable.

The car is riding sweet, and silent. Just as a proper Benz should.

Hopefully this thread will save someone else from pulling their hair out for a year+ (haven't got much left anymore).

Outstanding work.............and thanks for giving us the solution..............

Good job, thanks for the follow up.