What is this thing that I found in my airbox?
 

In the process of replacing my cracked lower CIS airbox section I found this thing inside it. WTF is it? Looks like some kind of valve or something, but it doesn't correspond to anything in the parts diagrams that I see. The new (replacement) air box doesn't have anything inside it that looks like this either.

I've also pulled the entire CIS system off the engine for general cleanup and so-on, and I haven't run across anything obviously missing or out of place or any logical location where this thing would go elsewhere on the engine.

Thanks in advance if anyone knows.

http://forums.pelicanparts.com/uploa...1197265746.jpg
http://forums.pelicanparts.com/uploa...1197265761.jpg
http://forums.pelicanparts.com/uploa...1197265788.jpg
http://forums.pelicanparts.com/uploa...1197265804.jpg

i am gonna punt!

i think that is the plunger found in the fuel distributer. i guess a past owner lost it? (or) if you took the top of the fuel dist off, i bet it slipped out. it is perfectly machined to fit the sleeve. dont let that sucker hit the ground. they are a perfect fit/match.

Man you're fast!

Thanks - I'll check the fuel distributor to see if it's missing any parts (I didn't pull it apart, just separated it from the air box and cleaned it up). Much appreciated!

Hmmm. . . Looking at the fuel dist. diagram doesn't show me any pieces that resemble this thing - do you happen to know where it goes exactly?

http://forums.pelicanparts.com/uploa...1197267262.jpg

that drawing doenst have it in it. i bet it is because the FD and that plunger are a matched pair, hench they have the same partnumber, (???) if you took the FD off the airbox, it is your plunger. it sits in the middle of the FD, and the air sensor bar lifts it into the FD, which gives your car the "go" juice. if you look at the bottom of the FD, it goes into that hole in the middle.

Gotcha. Much appreciated. I'll check it out first thing in the AM. That makes sense now that you're saying it and looking at the diagram and thinking about how the flapper valve underneath the F.D. works.

Somewhere I have a comprehensive CIS manual that might explain it also, but I figured I'd check here first. As always, Pelican delivers with the answer quickly.

Hoping to have everything back together and running well in a week or two. Just don't want to lose track of parts and where stuff goes.

that plunger needs to be handled with kid gloves. if it's damaged the least little bit, it will either bind in the fuel distributor bore or fuel will leak past it. be sure you put it back in gently and in the proper direction. the fit is so precise, with no o-ring or any kind of seal, that fuel doesn't leak past it.

Yes, it certainly looks like a precision part - nicely milled and all. Probably one of the reasons a new F.D. runs almost $2k. All I did was cleaned it up and (fortunately) haven't dropped it or whacked it on anything. Since I didn't have a chance to go down and look at the F.D. this morning, I'll ask you guys - is the proper orientation obvious for re-installation? I imagine the notched part needs to line up with the fuel inlet port and it would line up better one way versus the other (since it's not centered up on the shaft length-wise) but I guess it's worth asking the question since you folks are familiar with it.

the long end with the tapered tip is the outer end.

Wasn't the car running when you bought it?

Yes it was, but what started all this was that I stupidly cracked off the little plastic tab on the lower airbox where the straps hold the filter & cover (upper "aardvark" snout piece) onto it. I simply bungee-corded it on for a quick fix, but I am considering this car a restoration candidate, so I wasn't about to drive around forever with bungee cords holding my airbox together (this isn't a 944! :eek: ).

Also, I wanted to do a thorough assessment of the fuel lines and related components (especially after what happened on the 951) and to clean everything up as best I could "while I'm in there".

The odd part is I didn't remove that piece, when I pulled the airbox off and it was lying in there and I'm standing there staring at it like, "what the hell?" wondering where it came from.

That's how one learns I guess. . . :)

From the condition of the plunger, it doesn't look like it could have been running (properly at least). FYI, the workshop references say the plunger should only be cleaned/polished with a fine crocus cloth.

Brian

It's not entirely clear the order you have done things, but if all you did was pull the airbox off of a running car, and that control plunger was sitting in the airbox, then it's an extra one or something.

It can't just "fall out" of the fuel distributor.

P.S.

Here's a picture of where the control plunger goes and what it does.

http://www.auto-solve.com/illustrations/fuel_dissy.gif

Hmm. I just sprayed a little WD40 on it and wiped it off with a shop towel to get a little bit of crud off of it. I wonder if that'll mess it up. Hopefully not.

It's actually in pretty good shape - the pictures are a bit unflattering. There is some very slight cross-hatching evident in the outer shaft surface (almost like what you see in freshly honed cylinders) but you can't feel any distortion or grooves when you touch it or run a fingernail across it - feels smooth as glass. You can see this best in the 2nd photo. The middle part where the "indent" is has some ridges, but they look as if they were machined in there.

At the end of the day, I suspect it'll be fine. It is after all a hunk of billet steel, not a Ming vase. I'll treat it gently as I have up to now, but I think rumors of it having to be swathed in silk scarves and only lubricated with the rare nectar of the South African Nik-Nik bug are probably mythical in nature. I get the crocus cloth thing if I was polishing it, but I don't think it needs it. Seems pretty smooth.

To be careful, I'll wipe it with a microfiber towel though. Same goes for the housing. :)

That is entirely possible too. I'll have to check the F.D. to see if there's one in there. Given the number of weird things the P.O. did to this car, it wouldn't surprise me if he'd simply left an extra one sitting there.

I'll post back tonight with the findings.

I'm in agreement with "the." It must be an old one. I wonder if someone replaced the fuel distributor with a new one and left the plunger just laying in the air box?

Control Plunger
 

When I purchased (a non-running '76 911) it took me several months to troubleshoot what the starting problem was. Pulled off the FD (fuel distributor) and noticed the control plunger was stuck. I disloged it, cleaned, lubed, and replaced. But if this had happened before it might have been replaced it was improperly cleaned an no longer fit.

Just another possibility. If car starts/runs/etc. YOU HAVE a control plunger. I have a pic of how the control plunger fits into the FD. If you need to see this let me know and I'll hunt for it tonight.

Well, I just ran home quick for lunch and looked at the F.D. - it's a spare. The existing F.D. has its own plunger in place deep inside the recesses of the distributor (you can just barely see it in there with a mirror if you don't want to take the bottom end of the the unit apart, which I don't).

Funny thing for a P.O. to leave in there, don't you think? LOL!

Too bad he didn't leave me the rest of the other fuel distributor that thing originally went with - new ones are going for $2k! I bet I could have sold it for at least a couple hundred bucks! :)

Makes a cool paperweight though.

It does look like it has some wear to it as well as rust. I bet it was the leftovers from a past job. It may have some e-bay value.