Help needed... Ridiculous Problem

[Peter-E36]

Car failed NCT (MOT equivalent) over headlight alignment, got it done and went back, failed again, went back and the garage just can't get it right, they showed me the problem... The driver's side headlight is projecting 2 "lines" on the machine, and you can only get one of them to be within the tolerance...

I need to get the car retested for headlight alignment ASAP or else I'll have to get another full test again at more expense and more potential problems.

Any ideas what this could be or how to fix it? Car in question is 2003 E85 Z4 3.0i with Xenons.

Help!

 

[ph001]

Hmmm, obviously you know about the adjusters under the bonnet? I wonder if one of the internal reflector mounting is broken - you can get to the internals of the headlight quite well through the access hatch in the wheel arch. Maybe have a look inside the headlight and see if anything is loose.

 

[Coffee331]

Peter if it’s any use I have two headlamps in my garage. Take one and change out your bad one to get the test done.

 

[rally-chris]

Did they check if your main / dipped beam is operating correctly? The bi xenon headlights use a solenoid operated shutter inside the projector to shield the beam for the low beam function so I wonder if this is not working and the light is effectively on full beam?

(PS I assume pre facelift Z4 Xenons are bi-xenon like facelift and coupe?)

Chris

 

[Peter-E36]

Thanks Ray!

@ Chris, how do you check it? when the lights come on the headlights do that adjustment test thing where they point down and then up. Is that what you're referring to?

I'm not 100% sure if it's the same setup as the facelift, will need to do a bit of research.

 

[mjennings23]

It is a bi-xenon light both pre and post facelift, it's just the pre facelift cars use a secondary halogen as a "flash to pass" whereas I believe the facelift uses the xenon bulb for this purpose.

 

[Peter-E36]

Hmmm, obviously you know about the adjusters under the bonnet? I wonder if one of the internal reflector mounting is broken - you can get to the internals of the headlight quite well through the access hatch in the wheel arch. Maybe have a look inside the headlight and see if anything is loose.

Hi, they checked through the access hatch so I'd hope they had a proper look. If there's only one set of adjusters under the bonnet, then yes they knew about them. Might have a poke around it when I get home anyway to see.

It is a bi-xenon light both pre and post facelift, it's just the pre facelift cars use a secondary halogen as a "flash to pass" whereas I believe the facelift uses the xenon bulb for this purpose.

Thanks for the info! Good to know

 

[ph001]

@ Chris, how do you check it? when the lights come on the headlights do that adjustment test thing where they point down and then up. Is that what you're referring to?

No, that adjustment cycle is done via a servo motor at startup. After that, it adjusts the headlight beam angle depending on loading of the car which is sensed through a potentiometer and a link bar on the front and back suspension.

The shutter Chris is talking about is activated when you put your lights on full beam (rather than dipped) and vice versa.

 

[Monkeydonkeyratmagic]

Check if this is snapped like mine is. This is the levelling mechanism. If it's snapped this will be why.

 

[rally-chris]

A levelling fault isn't going to significantly change the shape of the headlight beam, and in any case it would be negated by the time the lights were re-adjusted to the correct height.

My point was does the affected headlight output from the main Xenon projector change between main and dipped beam, i.e. when you use the dip switch on the steering column stalk? If not, then the light could be stuck in 'main beam' and this is a different beam shape.

Chris

 

[rally-chris]

The Xenon shutter that cuts off the top of the beam for the dipped beam is the black bit shown on this image of a Z4 Xenon projector unit below:




Chris

 

[VRSteve]

Check if this is snapped like mine is. This is the levelling mechanism. If it's snapped this will be why.20180324_131224.jpg

If one side is OK, and the other isn't, its hardly going to be that is it?

 

[kis]

Check if this is snapped like mine is. This is the levelling mechanism. If it's snapped this will be why.20180324_131224.jpg

If one side is OK, and the other isn't, its hardly going to be that is it?

Why not? One of my headlights self levels. The other doesn’t budge at all. I assume it’s the same mechanism captured in the photo Monkeydonkeyratmagic? Any tips to how to get to it? Or even fix?

 

[VRSteve]

Check if this is snapped like mine is. This is the levelling mechanism. If it's snapped this will be why.20180324_131224.jpg

If one side is OK, and the other isn't, its hardly going to be that is it?

Why not? One of my headlights self levels. The other doesn’t budge at all. I assume it’s the same mechanism captured in the photo Monkeydonkeyratmagic? Any tips to how to get to it? Or even fix?

The mech in the photo is on the front drivers wishbone. Take the wheel off.

It controls the levelling on both head lights.

If one headlight levels OK, then it can't be the arm.

 

[kis]

That’s what it looked like but was unsure how the wishbone could play a part in the xenon height!

That screws my plans of an easy fix!

 

[Peter-E36]

Just in case anybody experiences the same problem... It was the bulb! Replaced the xenon bulb (100 Euro thank you very much) and hey presto, sorted