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-   -   Knock or pop noise from front end (https://mbworld.org/forums/e-class-w212/728213-knock-pop-noise-front-end.html)

Wenglish1984 11-24-2018 10:51 AM

Knock or pop noise from front end
 
hey everyone hope your all well I’m desperately looking for some help with a very Annoying noise issue from what I think is coming from the front end. It’s been happening for the last few weeks and I cant seem to find any issues.

The noise is a kind of knock/pop noise for instance if I’m parked up and pull off and then touch the brakes it will make the noise. If I then reverse and then tap the brake it again dose the noise. It’s not a constant noise only when pulling up or reversing etc.

ive taken all wheels off and checked brakes and arms etc and can’t seen anything wrong. I’ve had my father in law listen while on the drive going back and fore and he says it’s definitely front end noise but can’t pin point it.

In the last few months I’ve replaced all discs and pads using ATE and the rear suspension air bags not sure if anything is related

If anyone has had this issue previously could you please comment to save me taking it to a garage

Thank you

300SE1993 11-24-2018 06:39 PM

I have something like that happening once in a blue moon on mine. State inspections have never found anything loose, so not sure if it's a normal quirk.

Wenglish1984 11-25-2018 06:43 AM

Thanks for the reply this noise is constantly happening now definitely something wrong somewhere but can’t seem to find out where from �� Mercedes currently have a winter health check offer on at the moment for £29.99 so might just book it in for that and hopefully they find the issue for me

NachoLibre 11-26-2018 07:15 PM

Tight the lower control arm bolt.

Mud 11-26-2018 08:52 PM

Check upper and lower ball joints for any play plus the control arms as mentioned. Are you able to isolate which side?

Wenglish1984 11-27-2018 04:31 AM


Originally Posted by Mud (Post 7613931)
Check upper and lower ball joints for any play plus the control arms as mentioned. Are you able to isolate which side?

Thank you for the replys I'll definitely check the above as soon as it stops raining. With regards to which side I got a friend this time to listen while I went forward and back and he said it's coming from both sides but worse on the passenger side so I'm at a loss really.

nc211 11-28-2018 12:18 AM

Question - you put the car in reverse, start moving backwards and then tap brakes and hear the noise. But if you continue going backwards and tap the brakes again, the noise is gone. You then go forward, tap the brakes and hear the noise again, but continue going forward and tap the breaks again and the noise is gone. Am I correct?

You mentioned recently replacing the brake components. It sounds exactly like it’s your pads just adjusting to the new direction you’re traveling in. Some very minor slack in the area where the pads are hanging/mounted to the caliper. If I am correct, then you have nothing to worry about as it happens to many cars after new pads have been installed. My Toyota, VW and my MB all do this as all have received new OE pads and rotors over the past year.
Annoying a little, yes. But not a major problem.

PS, not sure where you live, but cold air will exaggerate this a little more as the metal contracts. In hot/humid summer, likely not an issue.

Wenglish1984 11-28-2018 06:45 AM


Originally Posted by nc211 (Post 7615081)
Question - you put the car in reverse, start moving backwards and then tap brakes and hear the noise. But if you continue going backwards and tap the brakes again, the noise is gone. You then go forward, tap the brakes and hear the noise again, but continue going forward and tap the breaks again and the noise is gone. Am I correct?

You mentioned recently replacing the brake components. It sounds exactly like it’s your pads just adjusting to the new direction you’re traveling in. Some very minor slack in the area where the pads are hanging/mounted to the caliper. If I am correct, then you have nothing to worry about as it happens to many cars after new pads have been installed. My Toyota, VW and my MB all do this as all have received new OE pads and rotors over the past year.
Annoying a little, yes. But not a major problem.

PS, not sure where you live, but cold air will exaggerate this a little more as the metal contracts. In hot/humid summer, likely not an issue.

Thank you very much for the detailed reply I'm very grateful. I've taken it into a garage this morning and no issues found with the suspension the guy thinks as you said the pads moving in the caliper.

I've been to. Mercedes today and purchased new pads and fitted them and it's exactly the same :( £70 wasted

It's such a loud annoying noise and I know it shouldn't do it which makes it worse I dread having to reverse into spaces due to the noise.

I think I'll have to take it into a Mercedes specialist to take a look

Thanks again mate

nc211 11-28-2018 10:47 AM

The solution is likely in the brackets on the pads and not the pads or rotors themselves. I can’t recall at the moment what the brackets are like, but may be a situation where one or two just need a little bend on a tab to make them a little more snug in the housing.

Mud 11-28-2018 12:56 PM

Great suggestion about the pads, I now remember years ago having that issue on another car.

Your brakes may look like this. Inner pad has a clip that fits into the piston, outer pad has a spring clip to provide tension.
https://cimg6.ibsrv.net/gimg/www.mbw...7e920b4841.jpg
https://cimg0.ibsrv.net/gimg/www.mbw...801358d1b6.jpg

The caliper mounting brackets themselves have some stainless steel insert clips as well that fit into the rail where the pad ears sit - do your mounting brackets have all new clips? Those clips are designed to cushion the pads as they want to move around.

Another source of noise (besides loose caliper mount bracket bolts that I doubt you have) are the slide pins. If they are very worn, the entire caliper can rock back and forth depending on wheel direction.

belarus27 11-29-2018 01:23 AM

Had this , right after installing new rotors and pads in front.
noticed next morning when i started backing out from garage , i heard like a thump/pop/knock. I could pinpoint it was the driver side. Found time to check and lubricate everything and also bent the metal brackets.
and the sound was gone. So im sure in my case it was the brackets. When i had them off i bent them in a little.
end of story


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