Noise at Startup, Only After Car Sits for 1-2 days
Thread Starter
Senior Member
Joined: Feb 2019
Posts: 337
Likes: 53
From: CA
2010 E550 Coupe
Noise at Startup, Only After Car Sits for 1-2 days
I have a single-tap or knock sort of noise at startup after my car has been sitting for a day or two. It just started within the last couple of weeks. The best way I can describe it is someone holding a drums stick and hitting a desk or something. It's just the one single thap/knock noise, and then it's never heard again until after the car sits for a day or two.
Could it be the starter? I kind of wanted to get some ideas before taking it to my mechanic. I trust him, but I also don't want to tempt him to rip me off lol.
Could it be the starter? I kind of wanted to get some ideas before taking it to my mechanic. I trust him, but I also don't want to tempt him to rip me off lol.
MBWorld Fanatic!
Joined: Jun 2008
Posts: 1,227
Likes: 61
From: Atlanta Metro
2008 clk550 - Navigator - Frontier
Without hearing the sound, it could be the purge (gas vapor) valve. It can make a "heavy" ticking sound. It to will generally go away once driving, until it gets really bad.
Thread Starter
Senior Member
Joined: Feb 2019
Posts: 337
Likes: 53
From: CA
2010 E550 Coupe
Thanks for the reply. It's not a ticking sound, just single thap/knock sound. Based on some general searching on Google, it doesn't seem like it's anything of immediate concern. I'll just bring it up to my mechanic next time I'm in.
Junior Member
Joined: Sep 2020
Posts: 55
Likes: 8
From: Portugal, in the countryside
CLK (W209) 270Cdi 2003
I don't know that engine (sadly), but, if it has hydraulic lifters, what comes to mind is a single lifter that loses its oil after sitting still for a long time. On the next startup, it would do one or more ticking or knocking noises until the oil pressure is restored within the lifter.
If it's that, it's usually not a major concern.
IT could be something else that relies on oil pressure, and takes a long time to drain.
If it's that, it's usually not a major concern.
IT could be something else that relies on oil pressure, and takes a long time to drain.
