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Wheel noise? '79 300TD

When I take hard left turns, pretty much only when turning 90 degrees onto a new street, I hear this "kwuk kwuk kwuk" in the back, kind of like plastic bottles rolling around in the back of my car. If I'm going faster, I tried through an intersection at 40mph or so the other day, and the sound was similar but the pitch of each noise and the frequency at which they occurred was higher (almost like a squeaking at that point). I've driven the car maybe four or five times since it started happening, hoping to get a chance to look underneath the car.

It /seems/ to be coming from the back right wheel, so I rolled that side up onto a wheel ramp (to emulate a left turn) but couldn't see anything that might be making contact with anything else. I took the wheel off, and while there was a spot on the rim that looked like it /could/ be rubbing somewhere (because it wasn't as dirty as the rest of the wheel), but I couldn't find anything that it might be rubbing on. With the car in neutral and the parking brake off, pulling on the wheel didn't indicate to me that anything was loose, and it certainly didn't bind or rub anywhere other than what I was getting from the brake pads.

So my initial thoughts were that maybe I needed to tear apart the wheel bearings and grease them up, although looking at Performance Products' online schematics makes it look like the bearings are possibly all sealed and maintenance-free. So new bearings then? Looking at the CD manual that I have, it looks like more of a job than I want to deal with, not to mention I haven't got any sufficient pullers or any of that jazz. I'd like to avoid the shop though, if I can; there's one local not-dealer Mercedes shop, they seem to do good work, but they don't entirely fill me with confidence.

thx,

-tom!

Reply to
Tom Plunket
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I drove it today again, to get some planting soil, and the "hard" left turns were accompanied by a sound more like an empty plastic bottle rapping on the axle. Thinking more about it, I realized I forgot a possibly-key bit of the puzzle in my last post.

A few weeks ago I replaced the oil in my hydropneumatic suspension. Unfortunately, the manual seems to be missing a page, but I opened the bleed screw, let everything drain out, then started the motor and let even more drain out ('til the reservoir was barely empty), filled the reservoir with clean and let it run, pumping out old oil 'til it was clear. Then I ran the "go down" operation into another bucket (instead of back into the reservoir) so I've got crystal-clear oil running through the system's veins.

Anyway, realizing that this might be the "cause", I'm wondering, is there a specific bleed operation I should do on this system? Just now, I put the car up on wheel ramps and released the level controller from the sway bar and operated the car for a couple of up-down cycles. It goes up and down pretty fast, but when I let it down I hear a distinct hissing like there's air going through the lines rather than oil. However, given the design of the system, I was guessing (hoping) it would be self-bleeding so I wouldn't really need to mess around with it anymore. Operating this system by hand, it kind of sticks; it's not as smooth as I'd like it to be, but I'm not excited about putting down $350 for a new level controller/distributor unit.

Anyway, I didn't get that same knocking sound when operating the system by hand but it did definitely "clunk" (although not as loud as what I'm complaining about) when changing the level controller from "raise" to "level".

Any ideas? I'm thinking about taking this job to the dealer, at least for diagnosis, but not sure how many of their mechanics have been there for 20+ years and know anything about this system. ;)

thanks,

-tom!

Reply to
Tom Plunket

It is probably the air bags in your hydropneumatic system... I don't have experience with this system but it does sound related... did the plucking sound happens after you do the bleeding?

Reply to
Tiger

Yeah the sound started a few days after I did the bleeding.

Sick of it, and not being able to see anything obvious with the car up on a jack or wheel ramps, I went by the dealer. Oh yes, I guess I didn't notice the sway bar just hanging there on the left side (I was convinced it was on the right, so that's where I focused my attention). So the coincidence is that I did the oil in the hydropneumatic system and a few days later break (???) the sway bar connection on one wheel. So it's all sorted now, and for $300 the dealer threw a full-car detail on top of all new sway bar bushings, so I'd say it was money well spent.

-tom!

Reply to
Tom Plunket

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