Common CLK 320 problem?
 

I have had a 2003 CLK 320 (W209) coupe for about 5 months now. It ran great this summer except for some rough shifting from 1st to 2nd gear, but driving in comfort mode fixed that. I had a fairly large service done at a local MB mechanic, and there is only one problem I have that I am not sure about.

I have always had a slight rumbling when driving around 25 mph in low rpms. It felt like I was driving over rough pavement or something and made a slight grinding noise. Now that the temperature has dropped to autumn levels I suddenly got some pretty bad rumbling when driving at 25 mph. It felt like I drove over some rumble strips for about 1.5 seconds. It repeated itself about 3 times, all along the same stretch of 25 mph, slightly uphill road. So I had to be gassing it just a bit to keep my speed up. Anyone know what causes this?

Some notes: I have read that this particular model could have had a bad radiator that leaked coolant into the transmission fluid, that explains my rough shifting from 1st to 2nd gear and I don't think that will get worse since I confirmed that the radiator has been changed to the Behr one. Is this also related to the former radiator problem? Any guidance would be helpful.

I guess I should also mention that it has about 119k miles on it.

Have you replaced the trans fluid? Do you have confirmation that the trans was fixed when the rad was changed?

I had that trans fluid flushed about four months ago. The guys couldn't figure out what was wrong with my transmission or why it jolted from first to second gear. I can't confirm, but I think my car came with a Valeo radiator that most likely caused the transmission problem, but I found another thread which explained how to check if your radiator is a Valeo or a newer Behr (is that the name? I can't remember). I definately have the newer radiator, but still worry about the damage done to the transmission.

In the last few days I haven't had any more rumbling, and it runs 100% smoothly once the engine heats up to about 50C. So maybe it was just a fluke or something. Or maybe I will have to wait and see what happens when the weather gets colder.

Don't know much about the transmission on the 320. However, the symptoms you describe sound a lot like a torque converter locking up prematurely.

Late model six speed Chrysler transmissions had this problem often. Most time reprograming or changing transmission filter and fluid took care of it.

You might ask your service advisor if this is a possiblity.

When your in sport mode your car starts off in 1st gear when your in comfort mode your car starts off in 2nd gear. I believe thats how it is for cars with 5spd transmissions. thats how my 06 350 is.

Hi haejuk,
I have the same car and exactly the same problems with the shifting between 1st and 2nd and the slight rumbling at this speed, the transmission oil was changed three months ago. I also get the same rumbling noice over 155 km/h. Can you tell us where was the problem with your car?
Thank you.

Just recovered from the same issue after a glycol contamination,

Have your mechanic perform adaption procedures for your Car, should fix it up.

Have it done asap.

It was the freilauf in the transmission. The name of the part is in German and I don`t know the name in English, but it looks like this:
https://cimg6.ibsrv.net/gimg/www.mbw...24c3b931ba.jpg

Also I have changed the radiator just in case :)
Thank you.

i had to change my conductor plate. Which whole job is about a 1000. You lose tranny fluid when that goes bad so filling up the fluid will only get you so far.