Knocking Noise on cold start
#1
Newbie
Thread Starter
Knocking Noise on cold start
My name is Peter I have a 2012 Mercedes E350 4Matic with 103,000 miles and I have been noticing a knocking noise or ticking on a cold start for about 2-3 mins and then it fades away. It's very consistent and I want to make sure it's nothing major. I do oil changes every 3k miles with 5w-40 liqui moly. I assumed it was chain tensioners, or cam adjusters. Apparently not because if it were chain tensioners or cam adjusters it's only supposed to last a few seconds. If anyone has any idea or advice on what it could I'd appreciate it a lot. Thank you in advance. Video of the sound is in the post.
Last edited by w212peter; 06-27-2024 at 09:06 PM.
#2
MBWorld Fanatic!
Join Date: Apr 2019
Location: Silicon Valley
Posts: 5,463
Received 3,372 Likes
on
2,244 Posts
MY'14 W212 M276 3.5NA @55kMi
NON STANDARD FARE
My name is Peter I have a 2012 Mercedes E350 4Matic with 103,000 miles and I have been noticing a knocking noise or ticking on a cold start for about 2-3 mins and then it fades away. It's very consistent and I want to make sure it's nothing major. I do oil changes every 3k miles with 5w-40 liqui moly. I assumed it was chain tensioners, or cam adjusters. Apparently not because if it were chain tensioners or cam adjusters it's only supposed to last a few seconds. If anyone has any idea or advice on what it could I'd appreciate it a lot. Thank you in advance. Video of the sound is in the post.
The cyclical knock says it's from a single cylinder.
It sounds like a rod knock.
Eventually this will get flagged by CEL as a MISFIRING fault code. A degraded cylinder with working ignition.
Are you familiar with oil analysis? You can collect an oil sample and get it analyzed for wear particles.
Last edited by CaliBenzDriver; 06-27-2024 at 11:15 PM.
The following users liked this post:
BenzV12 (06-29-2024)
#4
Newbie
Thread Starter
There is a service bulletin for knocking in crank assembly, the remedy is to replace pistons with wrist pins, rod bearings, and connecting rods. I’m just finding it so hard to believe if that is the issue though.
#5
MBWorld Fanatic!
Join Date: Apr 2019
Location: Silicon Valley
Posts: 5,463
Received 3,372 Likes
on
2,244 Posts
MY'14 W212 M276 3.5NA @55kMi
> PLAN B :
is a viscosity upgrade + drive into the groung gently or shortly.
Have a look at cylinder walls. Some of these engines suffer from oiling issues.
🤞