Doesn't sound like 'too high' is your problem, so maybe you have some failed rubber somewhere making noise.
Has anyone 'fixed' your suspension by adjusting the rod between control valve and torsion bar? If you want to investigate further, following should be approached with caution. A lift which keeps the car weight on the rear wheels is nice, or ramps would be OK to. If you have a real problem, the car may lower too far and crush anyone underneath if there is not sufficient clearance. With the car in unloaded state and 'ready to drive' , engine running, you disconnect the control rod, push the control valve arm to 'drain' which is the down position for a few seconds, then return the control valve is in the neutral position. That will allow the system to stabilize at base pressure, which should be enough pressure to hold the rear of the car at the correct height when it is not loaded. Measure again to see where your height is now. If no different, then you can probably assume that the control valve is working and adjusted correctly. -Max -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of andrew strasfogel Sent: Tuesday, July 13, 2010 11:44 PM To: Mercedes Discussion List Subject: Re: [MBZ] W123 wagon with jarring ride and and inaccuratespeedometer In that case, I'm roughly 1/2" too high. On Mon, Jul 12, 2010 at 11:15 AM, Dillon, Meade M CIV SPAWARSYSCEN-ATLANTIC, 53310 <[email protected]> wrote: > Middle. The tape should be held with some tension on it, and the > highest portion of the trim strip that touches the tape. > > -Max > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of andrew strasfogel > Sent: Monday, July 12, 2010 10:17 AM > To: Mercedes Discussion List > Subject: Re: [MBZ] W123 wagon with jarring ride and and > inaccuratespeedometer > > What part of the chrome trim strip - top, bottom, or middle?? > > > On Mon, Jul 12, 2010 at 8:18 AM, Dillon, Meade M CIV > SPAWARSYSCEN-ATLANTIC, 53310 <[email protected]> wrote: > > > Also, there is a shade-tree method for determining if your car's > > rear end height is correct or not. You should find 19 inches > > measuring from the center of the star in the wheel straight up and > > over the lip of the fender to the chrome/rubber trim strip. Plus or > > minus 0.5 inches is probably acceptable. > > > > -Max > > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On Behalf Of David Bruckmann > > Sent: Sunday, July 11, 2010 6:17 PM > > To: [email protected] > > Subject: Re: [MBZ] W123 wagon with jarring ride and and inaccurate > > speedometer > > > > I would proceed in the following order: > > > > 1. Check the rubber mounts at the top of the strut. If you had bad > > spheres, these mounts may well be pulverised/absent. Check also the > > bottom balljoint. > > > > 2. Test the function of the levelling valve (see instructions below) > > > > 3. Remove and test/replace the strut. A small leak is no definitive > > indication that it needs replacement (see permissible leakage below). > > > > Some clarifications/suggestions: > > > > Service document "32-501 - Functional Description" explains the role > > of each of the levelling system components. This document is > > available > > > at bruckmann.com/32-501.pdf and is also on the 115, 107, 123, and > > 126 service manual discs. > > > > -the nitrogen spheres provide variable-rate springing (only) when > > there is hydraulic pressure present. They do NOT have the damping > > effect of a shock absorber. > > > > -the shock absorbers/dampers are simple flow-constricting perforated > > discs located inside the struts. They travel back and forth on the > > end > > > of the piston, constricting flow in both directions. They don't > > normally "wear out" because there are no moving parts. I suppose it > > is > > > conceivable that flat spheres could damage the dampers (eg sudden > > pressure increases over bumps causing the o-ring around the damper > > to blow out). > > > > -the strut seals can eventually wear out, and will do so quicker if > > your cells/spheres are flat because of sudden pressure increases. > > Poor > > > maintenance (infrequent fluid/filter changes, dusty roads) can > > shorten > > > the life of the seals. A bit of leakage is permissible, up to 0.4L / > > 10,000km. > > > > -flat spheres will also destroy the ball joint at the bottom of the > > strut as well as the rubber mounts at the top. > > > > The latter is why I'm asking whether you "feel" the jarring, or > > whether you are just hearing it. If you just hear it, it could be > > the ball joint or rubber mounts. > > > > If you are so inclined, it is possible to check the struts for > > correct > > > damping function. This is described in another service document > > "32-510 > > - Checking spring struts". > > > > > > Here's an easy way to check that the levelling valve's base pressure > > is working correctly: > > > > 1. Raise the rear of the vehicle on ramps (better yet over a pit) > > and shut off the engine. Make sure the ramps are high enough to > > allow you sufficient space not to be crushed when you lower the > > car's hydraulic pressure and it drops a couple of inches! > > > > 2. Disconnect the leveling valve's lever from the sway bar. Put the > > lever in "emptying" position (towards the ground; away from the > > bleed > > screw) and leave it there. The car should NOT DROP. Then measure the > > height of a specific point on the car relative to the ground. Wait > > an hour or two. > > > > 5. After the delay (with engine off), measure the vehicle height > again. > > It should be exactly the same. If it is NOT, you have a leaky base > > pressure valve. > > > > The next step is important: > > > > 6. Engine off, position a drain pan and relieve the base pressure by > > opening the bleed screw on the levelling valve. The car MUST DROP > > significantly. Measure the height. If the car did NOT drop, your > > base pressure valve isn't working. A non-functional base pressure > > valve will result in a lower-than-normal ride height and poor > > damping, which > > > is most often resolved (incorrectly) by setting the levelling valve > > to > > > "fill" until the correct height is achieved. That hack leads to > > knocking noises, unstable ride height, and incorrect damping > behaviour. > > > > Note that the base pressure valve is internal to the levelling valve > > and operates completely independent of the position of the > > fill/drain > lever. > > The bleed screw is normally the only way of relieving the base > > pressure (aside from opening one of the hydraulic lines). There's an > > MB rebuild kit (used to be about $100) for the levelling valve that > may revive it. > > > > You may also find that the behaviour is temperature dependent (worse > > when hot). This further implicates the base pressure valve, which > > will > > > leak more when warm, causing lower pressure and generally bad > > behaviour in the system. > > > > D. > > > > > > Andrew Strasfogel wrote: > > > > > [snip] > > >The second issue is the hard, jarring thumps in the rear when I > > >drive > > > >over potholes. The lack of dampening was not cured when I > > >installed new air cells (accumulator sphere). The tech pointed > > >out, however, that one of my rear hydropneumatic struts was leaking > > >slightly. This > > > >seemed strange, considering that the car rides high and doesn't > > >settle when sitting. He said that the function of the struts was > > >to act as a shock absorber, yet I thought that was the job of the > > >air cells. Would > > > > >my problem resolve if I replaced the leaky strut? All other SLS > > >components (pump, rear valve) seem to be in order. > > > > > > > -- > > David Bruckmann, Palo Alto, CA > > Current Reality: > > 1970 Mercedes-Benz 220/8 (200,000 km) > > 1972 Mercedes-Benz 280SEL 4.5 (160,000 km) "Blauer Engel" > > 1973 Mercedes-Benz 450SLC (200,000 km) "Lottie" > > 1976 Citroen 2CV6 (145,000 km) "Piaf" http://dolly.bruckmann.com/ > > 1976 Mercedes-Benz 300D/8 (200,000 km) "Willow" > > 1979 Mercedes-Benz 300D (425,000 km) "Brown Betty" > > Shady Past: > > 1970 Citroen DS21 Pallas (170,000 km) "Goettin" > > 1971 Citroen DS21 Pallas (137,000 km), 1972 Citroen DS21 Pallas > > (502,000 > > km) > > 1978 Mercedes-Benz 300D (1,200,000 km or thereabouts) "Sieglinde" > > 1979 Mercedes-Benz 300TD non-turbo (260,000 km) "Diva" > > 1981 Citroen 2CV6 Charleston (120,00 0km), 1988 Merkur XR4Ti > > (209,000 > > km) > > 1981 Peugeot 505 GRD (350,000km), 1984 MB 300TD (385,000 km) > "Gertraud" > > 1985 Toyota Camry "The Slamry" (330,000 km) 1986 Renault 9 1.7L > > (155,000 > > km) > > 2002 VW Golf GLS TDI "The Hated Golf" (74,000 km) > > > > -------------------------------------------------------------------- > > -- > > > > _______________________________________ > > http://www.okiebenz.com > > For new and used parts go to www.okiebenz.com To search list > > archives http://www.okiebenz.com/archive/ > > > > To Unsubscribe or change delivery options go to: > > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > > > _______________________________________ > > http://www.okiebenz.com > > For new and used parts go to www.okiebenz.com To search list > > archives http://www.okiebenz.com/archive/ > > > > To Unsubscribe or change delivery options go to: > > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com To search list archives > http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com To search list archives > http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
