Today I changed the air filter of W126 1990 300SEL.
I now have extra parts and no clue where they go. This was supposed to be a Simple Job!

Viewing the engine from the front of the car, on the left side coming out of the air filter holder is a short hose, maybe about 3/4", that is clamped to a nipple. No problem there.

But also coming from the same place is a length of about 5" of thin white (yellow with age) tubing, looks thin like like a mediacl catheter. One end is by the filter holder or the short thick rubber hose (it's late and I can't remember), but the other end just dangles - what does it attach to?
A picture would be WONDERFUL but an explanation in words will of course also help.

AND lying in the same area I found a small black threaded cap about 1/2" tall and maybe 3/8" inside diameter. It looks like it should screw onto a threaded nipple somewhere to the left of the air filter cover but I don't see anywhere for it to go.

Would appreciate any help on this!!!

Thank you.

The other end should be attached to the rubber hose between the idle speed actuator (round aluminium thing in front of the injection system) and the manifold.

For the cap I have no idea. Maybe an old cap from a gearbox fluid bottle?

Rob

My '91 300SE has a small hard vacuum line that inserts into a small hole in the large L-shaped rubber hose on the air cleaner lid. the other end inserts into the fuel pressure regulator. The purpose is safety; to suck fuel fumes into the engine if the fuel regulator diaphragm fails.
The large L-shaped hose plugs into the valve cover to suck filtered air into the crankcase for PCV operation. The black threaded cap "might" have been placed over the lamda adjustment tower (sticks straight up out of the middle of the throttle body) if someone made a lambda adjustment and didn't replace the ball seal.

DG

Thank you very much.
The cap will remain a mystery, but I see what you mean about the small hard line. The reason I only saw about 4" and couldn't figure out where it connected is because it is broken. The rest of it is further down and goes underneath where I was looking.

What would happen if I drive the car without that line until I hve a chance to get a replacement line?

Got any pics?

To answer your question, nothing bad will happen if you drive the car without it provided:

1) Your fuel pressure regulator diaphragm doesn't rupture
2) You plug the hole in the breather hose to prevent dirt from getting in there and keep the breather suction good.

Is the cap a Schrader valve cap for an A/C line? Did you take it off and forget where, or did you just find it lying around somewhere? Or perhaps somebody used some Lucas product and left the cap lying around?


-tp

Thank you - talked me right out of it. I'll wait until I get a reolacement line.

I didn't take the cap off, it was just lying there where the L-shaped larger hose connectes to the valve cover.

Maybe somebody used it to plug the hole in the breather hose, where the fuel safety line goes.

-tp

Oh one more thing, you don't really need to replace the entire line if it won't reach. You can take a piece of rubber line that will fit snugly over the hard plastic line, and use it as a splice to attach another piece of plastic line.

This is sorta tricky, I had to do the same thing. The problem is that the breather hose hole is larger than the safety line, and won't fit snugly. There probably used to be a head on that line that would fit snugly. So what I did was get a short piece of rubber vac line, and put it over the the safety line. Then I took a piece of hard plastic line that was large enough to fit into the breather hose snugly, and shoved it into the vac line splice piece I made on the safety line. It's tricky to find a piece of rubber hose to splice with that will be snug on the skinner line and still accept the fatter one. I ultimately found a piece that did fit over both lines, but it wound up a little bit loose on the skinny line side. So I put rubber cement on the skinny line and shoved it in. Fixed.


-tp

Good plan - thank you!
I was only afraid that since it was such a thin line, if it was a vacuum line, and splice might reduce the little bit of vacuum that would exist there anyway.
It's broken in the middle, so maybe tomorrow I'll fool around with it, or the next day the dealer is right down the street. I don't imagine it would cost that much.
Thanks for your help and advice.