azmercedes

Sounds like upper valve train has drained dry or is not retaining lubrication for 5-10 seconds. Ideas, normal?

mrobinso

I've noticed this on our 2011 sometimes, but usually 1-2 seconds and doesn't always happen.

Maj. Dundee

Are you using the correct oil and just as important, are you using a fleece oil filter?

If you are using a paper filter, it collapses and prevents oil flow to the upper valve train.

https://bevo.mercedes-benz.com/bevolisten/229.5_en.html

leoparker990

Knocking noise on start up is something very common in the V6 MB engines. Normal or not it's another story. Many V6 engines have a start up timing chain slap which can be improved by replacing timing chain tensioner......

jkaetz

You didn't state which engine you have so this may not be relevant. The timing chain was stretched on our 2011 Bluetec after ~50k miles. Caused a rattle for 1-2 seconds on cold starts (oil pressure in the chain tensioner had been relieved).

anavabi

My 2008 ML350 has been sitting in the cold all winter. Not much driving. I've been turning the engine on at least once a week for 30 minutes or so to keep the battery alive. But earlier this evening when I tried to do the same, as soon the I turned the engine, there was a huge hissing sound, as if some pressurized gas or liquid was being relieved from the engine. I quickly turned off the car, and got out. The hissing sound started slowing down to a final stop after about 30 seconds. I looked under the hood, nothing obvious. Mind you it was late afternoon and lighting wasn't great. I did it again, same thing happened. It's very cold I couldn't stay to look further.
Meanwhile, wanted to pick your brains to see if someone has a similar experience. I wanted to start a new thread, but this thread came up in my search.
Thanks,

Maj. Dundee

I could be wrong, but I think I previously told you what to do when you are laying over a vehicle.

anavabi

Thanks. I'll let you know once completed.

anavabi

I took out the battery, took it to the part shop I'd purchased to test (they'd replace if damaged within warranty period), they put it under charge and tested. It came out with no defects. However, they said if happened again, they would replace it.
I replaced the fully charged battery and started the car again. This time, it started with no symptoms at all. I cleared all the thousands of error codes and re-scanned, no error whatsoever. Once again, it's amazing that how these cars are so sensitive to low battery charges. I have a BMW X5 and has no such sensitivity. Lesson relearned!
Hopefully with the warm weather around the corner, this will not happened. It was truly a scary experience.
Thanks Major for pointing me to the right direction and result.

stuttgart_londr

OLÁ PESSOAL