Opinions about this knock?
cls 450 2019 4 matic.
the knock comes from under the car i think engine to transmision

 

Hi, this is exactly the same noise as I have on my 2019 CLS450. It started very faintly at 30k miles, only I could hear it but now at 45k miles it's pretty audible. I'm praying it's not internal eg small ends etc perhaps it's an ancillary so water pump or alternator etc I believe that some ancillary items are electrical rather than belt driven so that will help isolating (if I knew which was which of course )
There is another post that turned out to be a hugely expensive engine swap as it was small ends and as noise is getting worse I'm going to take it to MB (or poss specialist) as soon as hols are over. Will update post with the result, please let me know if you find anything out,thanks.

 

Mb dealership says it s nothing wrong with the car, my mechanics told me that engine sounds good nut the knock comes from gearbox, next week i will go to a gearbox repair shop and i will make an update. Keep me in touch please

 

Interesting, I had the same response from MB but to be fair to them it was pretty quiet then, I could hear it as I was so used to the normal sound. But now it's louder and anyone can hear hit whilst the engine is idling.
I hadn't considered the gearbox but will be interesting to hear what your mechanic says, mine is linked to engine speed, increases frequency as you rev the engine in neutral l, so guess it's an input gear or bearing etc in the gearbox.
Unfortunate I've recently moved and don't have a MB specialist near me so won't be able to see them for 3 - 4 weeks. Will book myself in an update you then.

 

hello, any updates?

 

I'm on holiday at the moment, will book my car in for my return w/c 17th August so should have an update shortly after that.
John

 

hey, you solve the problem?

 

Not really I'm afraid. I took it too my garage (who have looked after my mercs for ten years, good place) and they said it's quite a faint noise still and if they took it apart they might not be able to easily find the problem. They suspect top end, tappets or poss cam bearings but didn't feel it was doing any further damage or would catastrophically break so advised me to carry on driving until it got significantly louder then bring it in. It's not ideal but I do trust them and it's better than another garage replacing bits one after another at great expense. So I'm still driving around, treating it gently, as you know you can't thrash it without being way over the speed limits anyway
I'll update this thread when I take it in, not sure when that will be.
How is your's coming along?

 

Hey, I have exactly same noise. Have 63k miles. Barely can hear on hot engine. But cold start idling. Can hear it. Since this engine was built with Chrysler most probably it's lifters. Cause I heard similar sound on chrysler engines. That's a bummer. Fortunately I still have Exclusive Warranty on it. So will just keep going till it explode or else.