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Headlight levelling system - hydraulic, pneumatic?

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plip1953
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Headlight levelling system - hydraulic, pneumatic?

Post by plip1953 » Wed Aug 15, 2018 7:55 pm

Sorry if this subject has been covered may times before.

My primary question is how are they meant to function, not whether they work or (most likely) don't.

And on a secondary point is, what is/are the most likely reasons for then failing?
Phil
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1988 Highline 635 CSi

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nick88highline
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Re: Headlight levelling system - hydraulic, pneumatic?

Post by nick88highline » Thu Aug 16, 2018 8:01 am

plip1953 wrote:
Wed Aug 15, 2018 7:55 pm
Sorry if this subject has been covered may times before.

My primary question is how are they meant to function, not whether they work or (most likely) don't.

And on a secondary point is, what is/are the most likely reasons for then failing?
It's a hydraulic system designed to function by pushing or pulling on the bottom of the headlights (the tops of which pivot on two ball joint mounts) which alters the beam height. The pushing/pulling action is created by a piston (one on each headlight) which is filled (with fluid) or evacuated by a control (a sort of rotary pump I think) inside the car. As you turn the control counter clockwise it draws in the hydraulic fluid and so pulls the headlights down, whilst turning it clockwise pushes the fluid out into the pistons pushing them outwards and the headlights up. The system was used on other great marques such as Porsche and Skoda.
What tends to happen is the pipes connecting the controller (inside the car) to the pistons on the headlights, crack and the fluid leaks out. Also the pistons themselves can seize up given their location under the headlights at the front of the car.
There have been a few posts about these things before but may be hard to find unless you know the keywords used in the posts.
Incidently the system is no longer available for RHD cars, but you can still get the LHD version which can be fitted, altough in a different way.
Nick
BMW 635CSiA (1988)
BMW i3 (2016)
Jeep Grand Cherokee V8 (2000)
Morris Minor 1000 (1968)

ron
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Re: Headlight levelling system - hydraulic, pneumatic?

Post by ron » Thu Aug 16, 2018 9:30 am

They are ALWAYS rustier than you thought!!!!!!
'88 High line.
'85 M #228
'85 M #207
'80 735i

plip1953
Posts: 42
Joined: Mon Aug 13, 2018 4:15 pm
Location: Leeds
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Re: Headlight levelling system - hydraulic, pneumatic?

Post by plip1953 » Thu Aug 16, 2018 11:19 am

Thanks guys.

I like to try to keep everything on the car working as it should and was pretty sure the system was functional a few years ago (last time the car was out of the garage). If I confirm no reaction between the adjuster rotary cockpit knob and beam height I'll most likely take everything apart and see anything obvious is causing it.

Phil
Phil
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