Vacuum/pneumatic headlight adjusters not working
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Joined: Jul 2018
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1998 Sprinter 312d Motorhome
Vacuum/pneumatic headlight adjusters not working
Hello and thanks in advance for any help with this.
I'm in the UK I've just bought a 20 year old motorhome based on Mercedes Sprinter 312D MWB 2.9 diesel.
The vacuum-operated headlight adjusters don't work and I wanted to know exactly how the system works and what are the components. e.g. from the thumb-wheel switch on the dash, do the vacuum pipes connect directly to the back of the headlights, or do they connect via another component? I'm going to change the headlights anyway, as they've seen better days. I've had the thumb-wheel switch off and when I blew through one vacuum connector, air came through the other connector, but not when I reversed the process and blew through the other side. Is that how it should be?
If anyone is familiar with what I've described, I'd be grateful for any pointers!
Thanks,
Brian
I'm in the UK I've just bought a 20 year old motorhome based on Mercedes Sprinter 312D MWB 2.9 diesel.
The vacuum-operated headlight adjusters don't work and I wanted to know exactly how the system works and what are the components. e.g. from the thumb-wheel switch on the dash, do the vacuum pipes connect directly to the back of the headlights, or do they connect via another component? I'm going to change the headlights anyway, as they've seen better days. I've had the thumb-wheel switch off and when I blew through one vacuum connector, air came through the other connector, but not when I reversed the process and blew through the other side. Is that how it should be?
If anyone is familiar with what I've described, I'd be grateful for any pointers!
Thanks,
Brian
Thread Starter
Newbie
Joined: Jul 2018
Posts: 2
Likes: 0
1998 Sprinter 312d Motorhome
Thanks for the advice Plutoe, I'll remember the VIN for future posts.
I spent more time checking the vacuum hoses and found 2 breaks in difficult to spot places and fixed them with windscreen washer tubing. Still didn't work.
As a last resort I switched the hoses on the back of the dash thumb-wheel switch and hey presto, it all works! 
A previous owner or garage had put them back on the wrong way round..
.....
Note to self, if there's evidence of previous work, don't assume it was done correctly.....
I spent more time checking the vacuum hoses and found 2 breaks in difficult to spot places and fixed them with windscreen washer tubing. Still didn't work.
As a last resort I switched the hoses on the back of the dash thumb-wheel switch and hey presto, it all works! A previous owner or garage had put them back on the wrong way round.......Note to self, if there's evidence of previous work, don't assume it was done correctly.....
