Knocking under chassis 27-37 mph
07-12-2018, 02:45 PM
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2014 c250
Knocking under chassis 27-37 mph
I have a knocking'ish kinda noise only at speeds between 27 and 37 mph. Don't hear it when car is cold, It get's noticeable after car is driven for 10 minutes or so, and most noticeable after longer drives, longer times/traffic.
It happens during accelerating, braking, coasting, in neutral. The sound is consistent, does not speed up or slow down. No vibration or performance problems.
Can't really pinpoint the exact location because if I sit in the back seat it sounds like its coming from the front, when I sit in front is sounds like its coming from back, and drivers side sounds like passenger side, and so on. Windows closed, no marbles anywhere (lol), this is definitely triggered when moving at the exactly the speeds of 27-37mph.
Would appreciate any advice, thoughts, ideas.
It happens during accelerating, braking, coasting, in neutral. The sound is consistent, does not speed up or slow down. No vibration or performance problems.
Can't really pinpoint the exact location because if I sit in the back seat it sounds like its coming from the front, when I sit in front is sounds like its coming from back, and drivers side sounds like passenger side, and so on. Windows closed, no marbles anywhere (lol), this is definitely triggered when moving at the exactly the speeds of 27-37mph.
Would appreciate any advice, thoughts, ideas.
07-12-2018, 05:00 PM
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2010 C300 4MATIC........ 2011 C63 AMG.............. 2015 CLS400 4MATIC.....
Take it to a shop with a lift that checks things for free and see if they can hear anything from underneath at those speeds.
Otherwise if it's something under load it might be harder to diagnose.
Otherwise if it's something under load it might be harder to diagnose.
07-12-2018, 05:57 PM
#3
Super Member
How many miles on her ? Doesn't seem drive line related per your description (constant repetition w/o change in engine revs/speed). Can you jack up the car and secure on jack stands so you can take a look see and start pushing things around, cats, resonator, pipes, might as well check the drive shaft/carrier bearing... Adi-Benz's advice would certainly clarify things.
