R129 HEADLIGHT ADJUSTMENT

Placey

Senior Member
Joined
Nov 10, 2003
Messages
46
Reaction score
0
Location
Preston, UK
Your Mercedes
R129 SL 500
Folks - the '93 R129 I have has the following problem:
The headlamp adjuster works - ie it will raise and lower the light beam, but it is not constant and under acceleration it dips and under lift off, the lights raise up. It seems the stability of the vaccum pressure is all to pot. When the engine is shut down, the lights dip right down. All other vacuum related things seems to work fine such as central locking.

Is there a non-return valve in the vacuum lines that may be faulty? If so, can anyone point me to a diagram of where it is!

Any ideas? Pretty sure it is not the switch. Oddly enough, I had the same issue with the last 126 I had and never solved it.

Many thanks
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
341
Age
87
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
I would check the connections where the pipes join to the inlet manifold, the pipe goes to the switch on the dash,and on the the headlamps. you could put your ear to this switch to see if you can hear it leaking, it will make a hiss if you turn the wheel, it could be a leak in either headlamp diaphragm. blanking off one pipe at a time could prove this.
 
OP
Placey

Placey

Senior Member
Joined
Nov 10, 2003
Messages
46
Reaction score
0
Location
Preston, UK
Your Mercedes
R129 SL 500
  • Thread Starter
  • Thread starter
  • #3
Thanks. I seem to have 'air' at the switch and at the head lamps but nothing to regulate the pressure or hold it.
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
341
Age
87
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
If the diaphragm in either lamp or the switch is leaking you will not have much vacuum in it
 
OP
Placey

Placey

Senior Member
Joined
Nov 10, 2003
Messages
46
Reaction score
0
Location
Preston, UK
Your Mercedes
R129 SL 500
  • Thread Starter
  • Thread starter
  • #5
Having checked all the vacuum lines (the ones I could see..) all seemed well - I was stumped. So I bought a new switch just in case I was wrong about the switch and hey presto - all is working normally again! Your advice, Malcolm, was spot on. Many thanks. :)
 

television

Always remembered RIP
Joined
Mar 14, 2005
Messages
164,073
Reaction score
341
Age
87
Location
Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
So pleased to have been able to help :D
 

AIB understand your special Mercedes deserves a special insurance policy. We have a refreshing attitude to insuring high performance, modified, imported or classic and vintage cars and deal with the UK’s leading insurers. We offer discounts for length of ownership, where the vehicle is kept overnight and limiting the mileage and can also cater for those clients who need higher mileage and business use. To obtain a quotation please call the team on 02380 268351 or visit us atAIB Insurance
Top Bottom