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Hey everyone new here and i have a problem with my 91' W124 230CE . The headlight adjuster doesn't work and there is an annoying weird hissing sound that comes from the headlight switch .which it disappears when i step on the gas pedal . Also the hissing sound changes volume if i move the headlight height adjustment high or low . I have checked the interwebs to find some solution to the problem but most of the opened threads with the same problem are too old and unanswered and non of them solved. I would really appreciate some help from you guys
Hey everyone new here and i have a problem with my 91' W124 230CE . The headlight adjuster doesn't work and there is an annoying weird hissing sound that comes from the headlight switch .which it disappears when i step on the gas pedal . Also the hissing sound changes volume if i move the headlight height adjustment high or low . I have checked the interwebs to find some solution to the problem but most of the opened threads with the same problem are too old and unanswered and non of them solved. I would really appreciate some help from you guys
Regards NSX-R
You must have a euro model, USA models don't have the headlight adjuster. The headlight adjuster works off of vacuum, there is a vacuum line that runs to the switch. Sounds like a vacuum line is leaking or the switch is leaking.
The sound goes away when you step on the gas, because doing so reduces the vacuum available. In very old cars, (50's and older), the windshield wipers ran off of vacuum. When you pressed the gas peddle hard, the wipers would stop working until vacuum was restored. The noise stops because the vacuum isn't at the switch when you push the gas peddle. You may have many vacuum lines that need attention.
These 124's have many things that work off of vacuum, and many people who restore them sometimes go to the trouble to replace all the vacuum lines in the car, there are many. Central Locking, Heater/AC controls, & Headlights adjusters all use vacuum.
In your case, pull the switch and start looking for vacuum leaks, see attached diagram of the headlight system
Last edited by ohollenbeck; 05-11-2019 at 11:34 PM.
You must have a euro model, USA models don't have the headlight adjuster. The headlight adjuster works off of vacuum, there is a vacuum line that runs to the switch. Sounds like a vacuum line is leaking or the switch is leaking.
The sound goes away when you step on the gas, because doing so reduces the vacuum available. In very old cars, (50's and older), the windshield wipers ran off of vacuum. When you pressed the gas peddle hard, the wipers would stop working until vacuum was restored. The noise stops because the vacuum isn't at the switch when you push the gas peddle. You may have many vacuum lines that need attention.
These 124's have many things that work off of vacuum, and many people who restore them sometimes go to the trouble to replace all the vacuum lines in the car, there are many. Central Locking, Heater/AC controls, & Headlights adjusters all use vacuum.
In your case, pull the switch and start looking for vacuum leaks, see attached diagram of the headlight system
Thanks for the detailed answer .Yes , i live in Germany . I’m gonna check it out and report back with pictures .
05-09-2019, 01:19 PM
