SLK 230/R170 - Headlight Adjustment Failure

[Stevitee]

Thanks Malcolm. I think I now have it sussed. Having changed the valve (which was duff) I re-inspected both headlamp connections, the pipes and so on and then noticed 'hissing' at the adjuster switch in the dash. Took the switch out - still connected to the pipes - and yes, that's where the leak is, in the switch. I have ordered a new one (don't ask how much!!) and will fit it this weekend and update this afterwards.

 

[television]

Thanks Malcolm. I think I now have it sussed. Having changed the valve (which was duff) I re-inspected both headlamp connections, the pipes and so on and then noticed 'hissing' at the adjuster switch in the dash. Took the switch out - still connected to the pipes - and yes, that's where the leak is, in the switch. I have ordered a new one (don't ask how much!!) and will fit it this weekend and update this afterwards.

Thank you for posting back on this,,I was sad that I had no more to offer on it and it will get fixed

 

[Stevitee]

Hello again - the latest update in the saga with which I am rapidly losing the will to live!

I have acquired a replacement switch having used the correct Part Number only to be given a another type which I am informed is 'the replacement type sir'. (£46 - I kid you not!)

For the anoraks amongst us, the correct part number for the Headlight 'Light Range (leveller) Adjuster' switch for an early SLK (up to 1999) is 1708000073. But, that's not available anymore and has been replaced with P/N A1688000373 which I am sure applies to W170s after 1999 to 2004 (?).

So, on the face of it, that's fine. However, the unsubtle difference between the two types is this:

The old type (mine) has two connections on the back, one for each vacuum pipe- one in and one out. The replacement type has three connections, all of which seem to be 'open', but as you will have surmised, I only have two pipes to connect to it.

The only clue on the MB parts database as to any 'modification' required as a result of the change is, and I quote 'vacuum pipe'. Not entirely helpful methinks.

So, has anybody else experienced this and could they advise me which permutation of two from three do I use to connect it correctly please? I appreciate that I could use trial and error but in an effort to know that I am doing it right and to not over stretch the ends of the carefully removed vacuum pipes any help will be appreciated.

Many thanks

 

[television]

Hello again - the latest update in the saga with which I am rapidly losing the will to live!

I have acquired a replacement switch having used the correct Part Number only to be given a another type which I am informed is 'the replacement type sir'. (£46 - I kid you not!)

For the anoraks amongst us, the correct part number for the Headlight 'Light Range (leveller) Adjuster' switch for an early SLK (up to 1999) is 1708000073. But, that's not available anymore and has been replaced with P/N A1688000373 which I am sure applies to W170s after 1999 to 2004 (?).

So, on the face of it, that's fine. However, the unsubtle difference between the two types is this:

The old type (mine) has two connections on the back, one for each vacuum pipe- one in and one out. The replacement type has three connections, all of which seem to be 'open', but as you will have surmised, I only have two pipes to connect to it.

The only clue on the MB parts database as to any 'modification' required as a result of the change is, and I quote 'vacuum pipe'. Not entirely helpful methinks.

So, has anybody else experienced this and could they advise me which permutation of two from three do I use to connect it correctly please? I appreciate that I could use trial and error but in an effort to know that I am doing it right and to not over stretch the ends of the carefully removed vacuum pipes any help will be appreciated.

Many thanks

You can work it out by blowing and sucking on the pipe outlets,, try it in all modes. I do know that for the downward movement the vacuum in the headlamp pipes is released

 

[Stevitee]

Hi Malcolm and thanks, that's helpful. So, if I understand this correctly, when the switch is at the top - position 1 - it is fully open allowing the full suction from the manifold to be applied to the heads to keep them uppermost. At position 2, presumably, it is halfway open, allowing only half 'suck' and thus the lights will drop slightly and in postion 3 its shut thus cutting off the suction at the heads altogether allowing them to rest in the fully downward position. Does that make sense?

If that's right - with the 'old' two connection/two pipe set up, how does the vacuum escape when the switch is shut (assuming my above analysis is right) to allow the lights to drop down? I wonder whether the third connection on the 'new' switch is the vent for the escaping vacuum perhaps.

I'll do some blowing and sucking ....as it were ..... and see what happens.

Thanks

 

[television]

On the old type switches you could hear the vacuum escape when the lights were fully down. probably through a hole in the casing. So yes fully open with the lamps at the normal running height

 

[Stevitee]

Hi Malcolm

It was the top and bottom connections, the middle one is the vent. All working now. Many thanks for all your help.

 

[television]

I am just pleased that you can now see where you are going,and it was a pleasure

 

[creepy coupe]

I’ve never really understood why we need a height adjustment on a SLK apart from a legal requirement, after all you can’t carry heavy loads and don’t have a rear passengers.

I have a question- is there a normal height adjustment screw on the light units, only having had to remove and replace the seals on my Wife’s SLK a few weeks back, she’s now getting flashed, I didn’t remember seeing any height adjuster screws.

 

[notanumber]

Yes there are normal adjustment screws for up & down & left & right .

 

[creepy coupe]

Yes there are normal adjustment screws for up & down & left & right .

Found them last night thanks, don't know how I missed them

 

[cmwi]

Hissing

Also have the same problem, hissing from the switch unless the dial is turned to the lowest setting. Have checked pipes on the rear and both are intact. Obviously with the leak from the switch the lights don't adjust and seem to be pointing down.
Bought a replacement from a breaker but it hisses more than the original (!) so it has gone back.
The pipes seem very brittle and easily crushed, is there a knack for getting them back on?
Have MOT next week so presumably a manual adjustment would sort it 'for now' until I bite the bullet and buy a new switch?
Thanks