92 e34 535i Power Steering/lad Leak

[quad121]

This morning noticed that when turning the wheel there was a groaning sound coming from the front. I checked the power steering/lad reservoir and it was very low. Topped it up and the noise disappeared.*As far as I know there must be a leak somewhere either with the power steering or the rear suspension levelling system.It's probably hopefully needing new pipes etc

[shogun]

Does your 535 really have LAD = hydraulic rear self levelling adjustment? That was only standard in E32 L = long version and E34 Touring.
Maybe just the hydraulic pressure hoses to/from the power steering pump. Or the connections under the power steering reservoir, old, hard hydraulic hoses.

[quad121]

Thank you for your quick response. I didn't know that only certain models had the lad system unless it was Alpina who fitted it to my car

[shogun]

do you have the VIN of the car? Not the Alpina VIN, the BMW VIN. Have only access to the BMW VIN, so can tell you how the car was originally supplied to Alpina for making the Alpina with it's own VIN.

If it is an Alpina, it might be EDC, not LAD, LAD is a hydraulic rear suspension system only, the power comes from the power steering pump which in this case is a double vane pump.
In case of EDC all 4 shocks are controlled electric/electronic, there is an EDC I version on early cars and from around 04/1990 there is the EDC III which is much more complicated. EDC III faults can be read by the DIS diagnosis system at BMW, EDC I not.
EDC you can easily recognise, there is a switch at the cente console with S and K, S for sports and K for German Konfort.

History of Vertical Dynamics
If we were to break down the common dynamic driving systems of today into the three coordinate axes by their principle of operation and assign them according to their function, BMW vehicles would have three different systems that would belong to the vertical dynamics systems. Vertical dynamics systems (effective direction mainly along the z-axis or vertical axis)
• VDC/EDC - Vertical Dynamics Control (Electronic Damper Control)
• EHC - Electronic Height Control
• ARS - Active Roll Stabilization (or Dynamic Drive)
EDC
An EDC was first fitted to a BMW in 1987, in the BMW E30 M3. EDC I was first fitted in series production in 1987 in the E32 (7 Series, 750i), which was based on the premise of manual toggling between a comfort and sports suspension setting. EDC II was then introduced in the E24 (6 Series). Even at this early stage of development, EDC functioned with characteristic curve mapping. Then in 1990, EDC III was fitted in the series production of the E31, E38 and E39. A modified form of this system, EDC-K, was also later to be found in the E65.
System Description
Chassis designs should be able to offer the driver (and occupants) the best possible standards in driving comfort, a very high level of driving safety, high agility and easy handling.
Conventional, non-adjustable vibration dampers are only able to achieve a compromise between these objectives. The electronically controlled damper system was developed to practically eliminate this conflict of objectives.
BMW EDC-K is a fully-automatic system that continually adjusts the damper settings to the current driving situation.
The fundamental difference between EDC-K and EDC III is the design of the EDC valves and their control logic. EDC-K thus improves driving comfort without impairing driving safety. If the damper settings are too soft or comfortable, the vehicle will quickly begin to vibrate on unfavorable road conditions. EDC-K remains in the soft damper setting for as long as possible and only changes immediately to the harder setting when the road situation requires it. The system also guarantees consistently good vibration damping characteristics however the vehicle is laden. In addition, all vehicle movements which have an effect on vehicle handling are monitored constantly by sensors. All measurement results are analyzed by a microprocessor and appropriate control commands are transferred to the dampers. The damping force at the damper is adjusted by solenoid valves with infinite variability in line with the changing road surface conditions, load status and handling characteristics.
http://www.bmwmotorsports.org/pdf/e70/04c_E70%20Vertical%20Dynamics%20Systems.pdf

[quad121]

I got under the car today and the leak is coming from the o/s pipe from the strut to the Pressure Accumulator.


Ive looked on RealOEM but it doesn't seem to show this part?

[shogun]

post the VIN, I assume it is a EURO version 1992 535i

but here is it anyway
Rear axle (http://bmwfans.info/parts/catalog/E34/Sedan/Europe/535i-M30/LHD/A/1992/may/browse/rear_axle/)

Pressure hose assembly 37 13 1 137 190 from '91, September — ... 2 pieces 0.242 kg / 0.534 lb €52.40 or $70.87 plus local tax

[quad121]

Ive put it into the stealers for the work :( as well as the hose the o/s Accumulator was also leaking. they get the parts say its gonna be ready today but then phone up saying the parts which have arrived are not the same as whats on the car so now they've placed the order for the (hopefully) correct parts but they're on back order and could take upto 1 week to arrive

[genphreak]

Nice history there... a good read, thanks!

I for one would like to find out more about how EDC works. One of my e34s has it (540iLE). My touring has LAD, which I like but is quite harsh going over bumps, it doesn't seem to dampen well, so maybe the shocks will need some work (I checked that the accumulators were still functional & not full of fluid) but perhaps just the mounts are shot (I haven't inspected them yet).