I am the proud NEW owner of a 1985 500SEL Blue/Tan with 215k miles.
I'm going through the basics of a tune up and have a couple of dumb questions:

(1) What is the hole for in the top of the air cleaner (air box) cover?
(2) What gap should I use? I read the thread and came up with 0.040" for Bosch W8DC
(3) How do I adjust the headlights. I follwed the user's manual and they don't seem to move.
(4) I have no instrument lights. Which fuse is it? Could the bulbs be burned out?
(5) How do I change the bulbs on the instrument cluster?
(6) Where can I find a map of the fuses? The documentation I have is not clear.
(7) What is the proper idle speed?
(8) The whine from the rear at highway speeds sounds like axle bearings, is this likely?
(9) The thumping from the right front sounds like ball joints, is this likely?
(10) The play in the steering wheel feels like a coupling failure, bushing failure, or tie rod, is this likely?

See the vehicle: http://www.cardomain.com/id/twombly

Any help you can provide is greatly appreciated.
Any guidance to find ansers is welcome.
Thank you. --Ben

 

Let's take these one at a time. First (1):

(1) So, what is that hole in the top of the air cleaner (air box)? Should it be closed? It would seem to let unfiltered air into the intake manifold from both the top and bottom. The fuel injector system has a post just below it but there is no apparent opening, nor apparent threads. This would seem to make it run poorly (like a vacuum leak). Correct?
(2) The wing nut on the top of the air box (which normally mounts the air box) only connects to the bottom of the air filter box to the top and does not hold it in place. This is odd. Correct?
(3) The two 10mm nuts on L and R sides seem to mount the bottom of the air box to the intake, correct?
(4) I put a short bolt in this hole and a nut on the other side with washers and closed it off, this also held the top and bottom of the air box together. It seems to run fine. Is there a problem with this?

Any comments folks?
Please?

 

The hole in the top of the air filter housing is to access the CO adjustment. That's in the post you mentioned, it's plugged to prevent tampering. They are all open like this and cause no vacuum leak.

 

I saw the Cadillac wreck i assume the "driver" is ur son?

 

Yes, and a very lucky boy.

 

Is there any harm in plugging this? It would seem to allow unfiltered air in. So I feel I may as well plug it.

 

Don't take this the way but did you get paid to engineer the best car that Mercedes offered that year? There must be a reason.

 

Good point. It just seems to be so odd. When I have oil changes people tell me I am mssing a bolt and proceed to show me how the air filter box moves around and is not secure. It is also odd that the two bolts that attach to the valve covers are the only attachments for the air box. The wing nut does nothing but connect the top to the bottom of the air box. Perhaps it is there in the event the air filter bcomes clogged and the mixture may get too rich? ... I just don't get it...

 

Did I say I love my 500SEL? It is as long as my Bentley and the same silky ride, but only the power-weight of my Caddie (now crashed).