Head Lamps Dip on Acceleration
 

1994 E420

I installed Euro Lamps last summer and recently added a vacuum adjustment control. I've checked my lines and connections... none are leaking.

If you have no vacuum leaks in the system, the check valve in the vacuum supply circuit needs to be replaced. On acceleration, manifold vacuum drops which is what permits the lights to dip. Further, if the headlight vacuum supply line doesn't have its own check valve I would add one otherwise vacuum leaks from other systems (like a leaking HVAC control system) will drain the vacuum to your headlights on long inclines. Mark

Thanks Mark

I'll go ahead and grab a Check Valve and see if that resolves the issue.

I believe that the factory installed system used an extra check valve with a separate vacuum reservoir.

Noted... I'll see If can look that up.

Adding a check valve reduced the dip. You notice it for moment on acceleration but its for the most part gone. Thanks!

early systems did use a reservoir, i had posted a schematic a few years ago, but cannot find it now, the later versions omitted the reservoir and used a special vacuum valve. let me know if you need a part number for the valve,

Find an Areo Star (ford) they have a small plastic vacuum tank by the a/c system passenger side rip it out and in stall it in your system you will have it all then.