SLK 230/R170 - Headlight Adjustment Failure

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I have searched the forum's many threads on this topic but can't quite find answer to this. Mine is an SLK 230 (1999). The headlight 'light range' adjustment is not working. I know that this is vacuum driven and like other models I assume other functions are too. I am not aware of any other functionality failings ie. central locking etc is working fine. However..........

With the engine running, if I disconnect the lilac vacuum pipes from the headlights there is no hiss or air being pumped out of them. So far as I can see all the pipes are still joined and undamaged.

This was present a few weeks ago when I mistakenly disconnected one of the headlight connectors when I was doing some work on the headlights. When I started the engine at that time there was an audible hissing ensuing from the disconnected pipe (which I reconnected). Now, as I say, there's nothing.

My guess is that the cause may be the valve (as opposed to the control switch) and having referred to the 'russian' diagram I can see that this is part number 0011406660. However (and this may seem daft) I need to know for sure whether the offending valve is the one that sits above the manifold on top of and at the left hand end of a metal 'pipe-like' component. It is held in a recess by a circlip with a diameter of about 1.4 inches.

Any guidance will be appreciated please. And if the valve is the one I have described, how is it removed and fitted? Is it a case of removing the circlip and pulling the valve out or are there other subtleties to the job?

Best regards and thanks in anticipation - Steve
 

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Have you looked under the dash at the pipes on the regulator, they often just come off
 
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Malcolm

Thanks for your reply (haven't been able to get here or work on the car today until now). I haven't been round the back of the regulator, thinking that if I investigated the valve first - as referred to in my post - and found that to be faulty I'd avoid having to mess about under the dash/remove trim etc. You see, what made me think that the valve was duff was when I disconnected the pipe from it, there was no air blowing from the outlet (or at the headlamp end) - with the engine running. Am I barking up the wrong tree? - of course, when I get a chance I'll check the back of the regulator but is the valve (or whatever it is) I referred to the right one?

Many thanks
 

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There should be suction on the pipe,but if the pipe is off the regulator in the cab or it is turned to its lowest position there will be nothing on the pipe that goes to the headlamp, so the engine pipe goes to the dash regulator first
 
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Ah ha, now I understand. Thank you Malcolm. At the next opportunity - probably next weekend - dark evenings and all that - I'll check the regulator. Incidentally, do the regulators ever fail (as opposed to the pipes falling off?) and can they be tinkered with to fix them?

Thanks
 

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Never had one go yet on the forum,,pipes off plenty of them :D:D
 

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Check around the battery,ive seen pipes damaged around there.
 
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Malcom, thank you, that's reassuring. I'll let you know.

5Spares - Thanks also. Had the battery out yesterday when tracing the route of the pipes in case it was trapped or something. However, all was well in that area - good point though.
 
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Hello again.......to continue....... I braved the dark and the chill to investigate the headlamp level switch. Easier than I feared, the headlamp switch panel just pops out with some careful prying with a screw driver and some padding underneath to protect the surrounding 'dash trim'. I thought that I'd have to remove all of the moulding from under the steering column (as one has to with a C class - and maybe others) so that was good. However, when checking the switch both of the pesky pipes are firmly in situ. So, what now? No hiss at the headlamp end/s - when there was about four weeks ago, when I had one of the connectors off mistakenly. I haven't done any work around the engine where the pipes are routed and in the cockpit I did have the radio out and back and have had it out again tonight to see whether the pipes pass that way and whether I might have disturbed something. I couldn't see the pipes pass throgh that vicinity so, a blank there. I am just wondering whether having run the engine with the connector removed from the headlight might have 'blown' something in the air system - lack of pressure and all that?

As I mentioned nothing else appears to be not working as it should so I am stumped. Any clues please.
 
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Thanks Rob. Sorry to be dense but what is a Midi Vac please? I assume its a vacuum tester but I have no knowledge. If I did get one, whereabouts in the system would I begin and what would I be looking for?

There appears to be a valve in the system (according to the 'russian' drawings) and further up this thread where I referred to what I thought was 'the' valve but I know realise I was looking at the wrong thing. Not sure where the right valve is but I'll endeavour to find it tomorrow - must somewhere on the exhaust side on the block?. Could it be this valve that's the problem?.
 

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I have one diagram of where to start,,, I need an Email address to send it
 
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Thank you.
 
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I have sent it and its all I have.

Pipe B is the one that drives the lamps,so you must have a vacuum here to start with
 
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Got it - thank you. If there is no vacuum,what is the likely cause if I am unable to find a broken pipe. Sorry to be a pest.
 

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That is OK there must be there as it comes out of the engine manifold,,only a vacuum at idle
 
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Thank you for the drawing. I removed 'pipe B' from the rubber coupling (that you can just see in the drawing) with the engine idling. There is a 'suck' at the coupling but it is only very slight - enough to just 'stick' it to the rubber 'surgeons' glove I was wearing but only just. I assume it should be stronger than that? What does that mean please?
 

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I do not know what is in the pipe, and have no info on that, it should come from the inlet manifold possibly via a one way valve, but without seeing it I do not know.

This is the source of the problem
 
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Ho folks.......back again.

Ok, so I have changed the check valve (P/No 001140660) that sits between the manifold outlet and the pipe to headlight adjustment 'circuit. The old valve was definitely knac**red because there was on flow either way if I blew into it from either end. The new one (princely sum of £18.34 it cost...and its tiny!!) is definitely a one way valve.

Ok, so all fitted. However, what I still don't know is the amount of 'suck' (for want of a better expression) is supposed to be come out from (out of?) the manifold end. There is some there but it doesn't hiss loudly or anything like that, just a lightish suck............with engine on tickover. Consequently, one headlight does now move - not dramatically and the other one (the furthest away in the system) still doesn't.

No, I haven't got a 'suckometer' or tester of that nature but can anyone tell me whether the 'suck' from the manifold is really strong or as I have described. The other question is - if the suck is quite light - does one have to run the car for a journey or two so that the vacuum can be built up in the system?

Apologies but I have never had to deal with this vacuum system business before. Regards
 

television

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I dont think that they make a sucometer :D Max vacuum is at idle. With no leaks the vacuum should build up quite quickly. your finger should stick on the pipe a little did you try the suction with the vale removed.
I will do another search
 


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