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Hydraulic headlight adjuster
https://forums.tipec.net/viewtopic.php?f=27&t=6128		 Page 1 of 1
Author:  lightning [ Fri Sep 25, 2009 6:59 am ]
Post subject:  Hydraulic headlight adjuster
Where is this located? Why does it stop working? Looking at the service history mine has had a couple of replacement parts in the past but has failed again within 2 or 3 years. The part seems to cost over £100, and needless to say it's not working!
Author:  stratfordshark [ Fri Sep 25, 2009 9:41 am ]
Post subject:  Re: Hydraulic headlight adjuster
I challenge you to find any 928 owner with working hydraulic adjusters. The system leaks so even if you top it up it will fail again literally within a fortnight. Would love to be corrected!

If you've downloaded the parts catalogue (free from Porsche site) you can see where the hydraulic tubes run.

928.org.uk site has a procedure for getting it working again using I seem to remember oil sourced from radio control shop! Only involves taking cover off position switch next to handbrake and pouring some oil down.

You can also replace the adjusters with solid plastic parts from US (fit base of headlight where piston usually attached) as they are not allowed adjusters there so system is modified on US cars.

There shouldn't be any mot implications if system is not working, as the screw adjusters allow beam to be set to correct position.

Porsche saw error of their ways and changed system in digi-dash 928s onwards to electric motors. Mine work fine but I recently had to replace one of the adjuster motors which cost about £50.
Author:  lightning [ Fri Sep 25, 2009 6:50 pm ]
Post subject:  Re: Hydraulic headlight adjuster
I don't know if my S4 is the "digi dash" version. I know, unreal...how can he not know that you say, but what does the "digi dash" look like? If I have the "toothed belt service" "fill washer bottle" "release parking brake" etc and the average MPG plus digital speed indication does that mean I have a "digi dash"?

If that's the case where are my headlamp adjusting motors located?
Author:  stepa1007 [ Fri Sep 25, 2009 9:48 pm ]
Post subject:  Re: Hydraulic headlight adjuster
lightning wrote:
I don't know if my S4 is the "digi dash" version. I know, unreal...how can he not know that you say, but what does the "digi dash" look like? If I have the "toothed belt service" "fill washer bottle" "release parking brake" etc and the average MPG plus digital speed indication does that mean I have a "digi dash"?

If that's the case where are my headlamp adjusting motors located?


If your car is a digi dash it will have no mechanical odometers but a row of three LED display windows under the clocks.
The electric adjustment on 944 Turbos never works either....

Stephen
Author:  stratfordshark [ Fri Sep 25, 2009 10:03 pm ]
Post subject:  Re: Hydraulic headlight adjuster
lightning wrote:
I don't know if my S4 is the "digi dash" version. I know, unreal...how can he not know that you say, but what does the "digi dash" look like? If I have the "toothed belt service" "fill washer bottle" "release parking brake" etc and the average MPG plus digital speed indication does that mean I have a "digi dash"?

If that's the case where are my headlamp adjusting motors located?


You have the "digi-dash". The 87 and 88 MY S4s had the analogue dash:
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I may be wrong about digi-dash = electric adjusters. What year is your car (always useful to include it in signature as 928 electrics changed year to year in important details)?

The 928 electric system is very reliable. The motors are situated directly behind the yoke holding each headlight. I can't recall if they are visible with lights raised, but they are obvious from inside wheel well when splash liners are removed.

I'll try to establish when electric adjusters were fitted, but with hydraulic system I think the knob by handbrake rotates continuously. With the electrics you will feel 3 distinct clicks as you move it between positions.
Author:  stratfordshark [ Fri Sep 25, 2009 10:16 pm ]
Post subject:  Re: Hydraulic headlight adjuster
OK Lightning I have a feeling your car is a 1989 model year (built from Sep 88 onwards).

The wiring diagrams only show an electrical potentiometer for MY 1990 sheets onwards, though digi-dash introduced MY 89. So the 1989 MY has the digi-dash but if I'm reading wiring diagrams correctly still has the hydraulic headlight adjusters.

It's not simple either to convert to electric adjusters, as the headlight yoke changed design to accommodate the motors.

If your system is electric then we can go from there to see which parts of system have failed.

With lights raised and headlight cowl removed look at the base of the headlight where there is a ball and socket joint for the aim adjuster system. With the electrics this is attached to the plastic piston of the adjuster motor. I'm pretty sure that on the hydraulics there's a sort of elastic cable ending in ball which is attached to this socket. That's from memory of removing headlight from my 88 S4 several years ago so a bit hazy!
Author:  lightning [ Sat Sep 26, 2009 8:33 am ]
Post subject:  Re: Hydraulic headlight adjuster
Thanks for the replies. The adjuster next to the seat has no distinct clicks. it just goes round and round, although it comes to a stop after a couple of turns.
The car was delivered in Feb 1989 and I definately have the "digi dash", I'll have a look at the headlight adjusters but it looks like I have the hydraulic system on my car. The lights are pretty good, alignment is fine, so it's no real problem if the adjusters are not working. I've got some hydraulic oil that was for the electric/hydraulic hood on my BMW Z3 so I'll try some of that in it.

Should there be a plastic liner at the back of the OSR wheel arch? It seems that mud and water can just be flung up on to the inside of the fuel filler and inside the wheel arch. There's no liner or visible brackets, just a thin half-inch metal strip acting as a brace to secure the corner of the rear bumper.
However none of the parts are rusty, it just looks like there should be a liner. It does have one at the front (of the rear wheel arch)
Author:  stratfordshark [ Sat Sep 26, 2009 9:07 am ]
Post subject:  Re: Hydraulic headlight adjuster
You definitely have hydraulic adjuster. The electrical one is a 4 position switch which switches 4 different size resistors into circuit. The adjsuter motor is shown below just for interest. You can see its piston poking out at base of headlight yoke.

On the wheel liners you've identified a weak point on 928 design! The rear offside liner was only introduced for MY 1990 on. Prior to that you're right that it resulted in loads of crud being kicked up into back of arch and fuel pump cover. Even with a liner there if there are any gaps it's vulnerable to corrosion (happened on rear nearside of my last 1988 S4).

You should consider taking off the wheel and having a good clean out there. Also remove cover of fuel filter/pump (two nuts - 10mm I think - higher up behind bumper) as they'll be a lot of mud under that cover.

ps if you download the parts catalogue (Porsche website, classic section) then this is very useful as it has beautiful drawings of every system/part, and the listings show when certain parts changed or were included. I just checked mine to confirm that the OSR liner was 1990 on.

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