560 SEL hydraulic suspension question

[SteveH]

Can anyone give me an idea how much hydraulic fluid should be in the reservoir in the engine bay for the hydraulic suspension? I can't see a min/max level line on the reservoir anywhere. Mine's filled about half way up.

Thanks!

[big d]

It have a dipstick with lines.Just pull up and you will see it.It is about right if is half way in bottle.

[partsman225]

If no dipstick add until about 3 inches to the top

I got a 91 560Sel with 28 yrs experience.

[SteveH]

cool; thanks guys, I'll check this out.

[Hit Man X]

Chances are the system is dirty... you may want to pick up a new filter and a gallon or two of hydraulic oil to flush it.

Just run a small dia rubber hose to an old milk jug for the return side and prefill the reservoir. It will just pump out normally. I think I used 1/4" ID clear hose.

[SteveH]

Thanks Hitman. Sorry for the silly questions, but where do I attach the rubber hose? Do I attach to the bleeder valve at the back of the car?

Also, what cheap fluid should I use to flush? Is there a particular sort of hydraulic fluid, or will any sort do for flush? I understand MB is particularly proud of their fluid, so I would prefer to only use it for the final fill-up.

BTW; I got the suspension doo-hickey in the rear, attached to the sway bar, unfrozen. It had been gunked up, and was not moving the linkage attached to it. I cleaned that up and tested it, and it was clearly lifting the suspension when I pushed/pulled on the valve arm. That said, the rear suspension still "clunks" when I roll over bumps/holes in the pavement; even very small ones. This seems particularly evident on the right side. I looked at the shocks, and both seem to have had a split in the rubber accordion sleeve at the bottom of the shock, but there doesn't appear to be any fluid leaking from either one. I noticed that the fluid in the reservoir is a little low; could the lack of sufficient fluid be causing the clunking?

Thanks!

[Hit Man X]

Originally Posted by SteveH

Thanks Hitman. Sorry for the silly questions, but where do I attach the rubber hose? Do I attach to the bleeder valve at the back of the car?

Also, what cheap fluid should I use to flush? Is there a particular sort of hydraulic fluid, or will any sort do for flush? I understand MB is particularly proud of their fluid, so I would prefer to only use it for the final fill-up.

BTW; I got the suspension doo-hickey in the rear, attached to the sway bar, unfrozen. It had been gunked up, and was not moving the linkage attached to it. I cleaned that up and tested it, and it was clearly lifting the suspension when I pushed/pulled on the valve arm. That said, the rear suspension still "clunks" when I roll over bumps/holes in the pavement; even very small ones. This seems particularly evident on the right side. I looked at the shocks, and both seem to have had a split in the rubber accordion sleeve at the bottom of the shock, but there doesn't appear to be any fluid leaking from either one. I noticed that the fluid in the reservoir is a little low; could the lack of sufficient fluid be causing the clunking?

Thanks!

Rubber hose hooks to that hard pipe on the reservoir under the hood. Just heat it a bit with a heat gun, lighter, etc so it will slip over the pipe and be snug. That way when the car is idling it will pump the fluid right out.

The fluid I use in mine is ISO 46 from Tractor Supply. $20-25 for about two gallons.



Are you sure the clunking is in the rear? I have experienced clunking up front when my guide rods were wasted. They are not hard to replace to me, but finding a competent alignment shop to set the caster to spec will be hard.

[SteveH]

yeah; the clunk is definitely in the rear; I can feel and hear it. The front wheels also have their issues; they feel a little "loose," especially on uneven surfaces, such as driving on dirt road or field (parked it for church in open field last Sunday, and could audibly notice significant "rattling" of the suspension, both front and rear. I pushed and and pulled on the various links up front last weekend, and looked for broken/cracked seals, etc; everything seemed to be still in spec, so it's a bit puzzling to me...

Anyway, thank you for the guidance here!

[Hit Man X]

Well the upper rear hydraulic shock mount could be loose or worn. It is just a pair of rubber bushings. Maybe diff mount. You will have to get in there and look around.

If your front end has never been done, it is probably well past time. Chances are you need lower ball joints and guide rods... well that means you have to dismantle pretty much everything so you should just go ahead and do lower control arm bushings and upper arms. Sounds horrible, but it is not. I can do a front end in a few days now.

[Ritchie]

Sounds like what I went through.

I replaced my rear subframe bushings and differential mount. I still get the "clunk" but not near as bad but it now drives tons better. I will be replacing the rear shock top mount bushings next.

I also replaced the guide rod mounts too. Now the front end feels tight. I used to feel it "flex backward / forward) " a bit just before coming to a stop and releasing the brakes.

I have two new guidrod mounts. I bought them then found a set of Lemforder brand ones. So if your interested in the Febi's PM me.

[SteveH]

Thanks guys; I'll definitely look around in the back. As for the front; I'll look closer; things looked ok and didn't move around, but I'll jack it up and get a little more involved with it.