does the hyd suspension "bleed down" - PeachParts Mercedes-Benz Forum

odie · #1 03-11-2005, 12:30 PM

My wagon's rear hyd suspension bleeds down or something at night. Every morning when I start the car, the rear rises up about 2 inches. All day long as I drive, park, drive, park, etc, etc, etc...the rear of the car stays up.

But if I park for an extended time, mainly over night, the rear seems to bleed down.

I have never noticed any loss of fluid in the system.

Is this over night settling normal for the self leveling suspensions?

leathermang · #2 03-11-2005, 12:58 PM

Yes it is.

lrg · #3 03-11-2005, 01:39 PM

To a point a small amount of sag is OK but if it's dropping two inches it's too much. Most likely your rear actuator valve is leaking internally which allows the pressure holding up the rear end to bleed off. It can be fixed with a rebuild kit from the dealer. There is another thread titled "Rear Suspension" now going on that has all the details.

phidauex · #4 03-11-2005, 01:59 PM

My actuator valve was rebuilt by the PO, and it doesn't sag at all. In fact, I've tried to detect sag when I start the car after having it sit for a few days, and I never see it rise up. However, the self leveling function does work, and the rear sits at a good level all the time.

I think your problem is a fairly common one, and not a very severe. I've heard valve rebuilds are among the cheaper things to fix on the rear suspension. (not like the pump replacement on mine ($$$)).

peace,
sam

odie · #5 03-11-2005, 02:01 PM

I have not measured how much it settles...

If I leave my foot on the ground when I get it and start, I can feel the car rising up. It feels like a couple inches, but maybe that is just because it rises for about 2-3 seconds.

billrei · #6 03-11-2005, 02:06 PM

I have left my 1980 300TD parked for a week at the airport and I hardly noticed any change in suspension height so would say you definately have an internal leak. I guess I'm just luckly since carbon dating of the accumulated crud on the valve shows its never been touched....

odie · #7 03-11-2005, 02:08 PM

Sounds like the settling is not nromal.

But is it worth fixing? Can I do more damage by trying to fix it? As long as it pumps up while driving, why bother?

billrei · #8 03-11-2005, 02:13 PM

Quote:

Originally Posted by odie

Sounds like the settling is not nromal.

But is it worth fixing? Can I do more damage by trying to fix it? As long as it pumps up while driving, why bother?

I don't think you can do any harm by leaving it alone. Only when the leak is external is immediate attention required. Just enjoy the ride in the morning!

lrg · #9 03-11-2005, 02:15 PM

If you can feel the rear rise on startup it's not normal. Mine went unfixed for quite a while and I don't think it causes any harm but I got tired of seeing it look like a lowrider every morning. I suppose over time the leak would get worse and it will eventually sag at shutdown. Until then I'm not sure it makes a difference.

dieseldiehard · #10 03-11-2005, 02:38 PM

The only time my '79 wagon sagged was when I loaded it up with 1200 LBs of ceramic tiles. I drove it carefully and she perked up OK but I could hear the pressure lines singing all the way home (made two trips like that incidentally!)

WannaWagon · #11 03-11-2005, 02:49 PM

Mine sags overnight, too. Seems to be more of a problem in cold weather. Anybody got a part number for the rebuild kit and a DIY writeup?

WannaWagon · #12 03-11-2005, 02:52 PM

Nevermind on the part number. It's already posted in the current "rear suspension" discussion.

billrei · #13 03-11-2005, 03:10 PM

Quote:

Originally Posted by WannaWagon

Mine sags overnight, too. Seems to be more of a problem in cold weather. Anybody got a part number for the rebuild kit and a DIY writeup?

I think the key parts (the ones that leak) are just a couple of hardware store $0.10 O-rings. If you can afford extra downtime I would tear down the valve first and determine what needs to be replaced, before forking over 60 bucks to the MB profit center....In 5 years of veteran MB ownership I have yet to go to the Stealer for parts...

odie · #14 03-11-2005, 03:20 PM

mine does not look like a low rider in the morning. It's really not even noticable. Only if I leave my left foot on the ground while sitting in the car do I feel the car rise up during starting.

Maybe one of these days, when I have absolutely nothing else to do, I might poke around and see what seal or valve is bleeding and see about fixing it.

phidauex · #15 03-11-2005, 05:17 PM

If I were you I'd write down the part numbers and keep it in the back of your mind. At some point the valve will be internally leaking so bad that it can't pump up faster than it sags, and you'll drag your ass around. That effect would be worse while loaded than while unloaded. Then you'll want to fix it.

I wouldn't mess with it now unless you are looking for a project. (which I know we do sometimes

). Its always possible that you'll strip a fitting or something like that while removing the valve, and there is no use opening that pandora's box until you have to.

peace,
sam

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