kn51

I've searched and searched, but this is a new one for me and I need to ask advice.

The "clunk" occurs only when the car is cold. As in, if I start it, it clunks. If I shut if off, wait a minute and restart, no clunk. After a couple hours, it clunks.

The clunk occurs approximately a few seconds, right when the headlights do their thing.

I'm still trying to get the WIS manual going to see locations of components. The clunk feels like it is right under the driver footwell. Is their an ABC component in those parts?

Mike5215

I believe the ABC valve body is in the tranny, which might feel like it's under your feet. ALX will probably come by shortly and give you some actual technical advice.

alx

Lol... No actual technical advice this time, but here are some speculations

I would check the secondary air injection pump. Off the top of my head that is one thing that activates when engine is cold.

Abc has two valve blocks- one front and one back. They generally don't clunk, but who knows...

It could be a dead abc accumulator... You have a few of those...

It could be many things.

I would raise car and try to make it clunk and listen...

Arriagunter

Good afternoon.

I'm having the same problem. A loud clunk after a cold start. Did you solve the problem?

Thanks in advance.

Arriagunter

kn51

Holy time machine. And here I hate it when reading a thread and there is no follow up on the one specific thing I had while looking for an answer...and now I'm guilty of it. In my defense, it took me a while to finally get the car in to have it looked at and the car was new to me at the time.

They ended up replacing a couple ABC hoses since they were leaking. Along with that they also replaced the front accumulator. It took care of the problem.

Arriagunter

Thank you. I'll give it a try. I replaced mine in a C215 and wasn't hard at all.

vettebk

I had a similar problem and it was resolved by a new hose and accumulator. My advice is to change the ABC filter and green Pentocin fluid every 20K miles. It is worth it to do the regular maintenance.

ItalianJoe1

There was another thread of an SL doing this from the rear and it was also an accumulator. If one is failing, replace them all, they are all getting close to failing if one did. Should be 4 in total, one on each valve block and one on the return line from the rear.

tx170754

Check your struts first, if your car makes this "loud clunk" when is cold you could have a leak in the system....my car did the same and it was a rear strut leaking.

Arriagunter

Thank you guys. I ordered a front accumulator. Will replace and tell what happened.

vettebk

You might think about changing the ABC filter when you change out the accumulator. The filter typically is date coded which is good information to know. I would also change the green pentocin fluid if it has not been changed in the last two years. The secret to ABC is keeping things clean.

Keep us posted.

Arriagunter

SOLVED. After replacing front accumulator, noise disapparead. Easy task. I recommend using a 24 mm wrench.

P/N for my '06 S600 is A2213270215. Cost me 203,32 EUR + shipping on eBay.

Thank you all!

BenzV12

I love it when I see someone solves his problem and provides a feedback later
Happy Driving