LowKeyCL600

Hello everyone. I have a 2001 CL600 and after I drive for a short while (10mins or so) and I go over a few normal bumps/dips in the road, the car's suspension raises all the way up and I can not bring it down. The only way to bring it down is to shut the car off, then it immediate goes down. When I restart the car and drive off, a couple of minutes later the rear end drops too low and my tires scrape the inner wheel well for 10-15 seconds, then it raises back to normal height until it raises all the way up again (quite frustrating). Has anyone had this issue before? How did you resolve it? Any suggestions on what I should check? I have an appointment with the Mercedes service center near my home next Tuesday, but I could try something before then, I will. I did change the ABC filter, no difference. Any ideas/suggestions would be much appreciated. Thank you

Jack_88

My guess is a rear valve block failure. It's an easy and cheap part to refurbish, do some searches to find the thread. Hardest part is getting it back in, provided you don't have a second set of hands to help. It may help to visit someone who has STAR to do a scan first, though, see if any codes that may point you in the right direction are lurking about.

Jack_88

Oh, and when you changed the ABC filter, did you do a flush as well? Changing the filter alone helps nothing. The fluid needs to be changed as it degrades over time and use, and also can have moisture introduced, which is hard on the valves in the system and can contribute to a failure. Doing a fluid swap is very easy, but requires two people.

LowKeyCL600

Thank you Jack, I will look further into it. I do have an appointment with MB just to do a diagnostic on the ABC and they will tell me what's wrong. If it's something I can fix myself, I will. I didn't change the fluid when I installed the new filter. I did buy 1 can of flid just in case I needed it, but I'm sure if I flushed the system I will need quite a few cans, correct? Do I just empty the fluid that is in there or do I also run new fluid through as well to have it empty out too? Thanks.

Jack_88

10 liters is what you need to be sure, although you won't likely use all of it. I pulled the return line from the reservoir, attached a clear hose and ran it into a bucket. Next, I had someone raise and lower the suspension while I kept adding fluid to the reservoir. Note that there is a delay between the car changing height and the reservoir lowering. You do not want air introduced into the system, and when it does drain, it does it fairly quickly. As long as you pay close attention, it's simple enough. When you notice the fluid going through the clear hose looks like the fluid you are putting in, you are done.

You will need a new filter since the one you put in probably had it's life significantly shortened by running already dirty fluid through it.

For the Pentosin, I bought two of these, including the valve block rebuild: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

The valve block rebuild is not difficult, the only thing is to be careful with the fittings when removing it from the car. They can be on there pretty good and aren't hard to strip, so your wrench needs to be the right size and well seated, don't use a crescent wrench on this one. A crow's foot wrench is the best bet for a couple of them. Also remember the rear suspension will lose all pressure and bottom out when you take those lines off, so make sure the car is on jack stands.