CIS airbox: Can you remove just the top part ?
 

Long story short - the car backfired and spat its pop off valve while at the mechanic. He glued it back on (funny) as you can see
but since then, the car has an irregular idle - even when warm, so I drive it with the hand throttle set to 1000 RPM to not stall...

As you can see this hole on the picture is devoid of a screw and does not seem threaded. Did it spit out that screw ?

http://members.rennlist.com/greg/911t_airbox.jpg

My question: Can I remove the top part of the airbox see here (so I can inspect the bottom part under the pop off valve and udner that missing screw?) without doing a partial drop ? I just want to crack it opne and peek, not necessarily remove it all... Sneak and peek... I don't want to pull the entire airbox, I know the intake hoses are all new, I just want to see that area under where that missing screw is... See if that's cracked or what and if I Can epoxy something... Carb cleaner does not change idle, opening the oil cap either, I think I can hear a massive suction noise too, but that could be me, if that were true the car would not run at all - while all it has is a tendency to hunt between 600 and 900 rpm and die if left alone - it's great at speed !!!

the missing screw and the one behind it that is partially out, tell you that the box has split and you have a large air leak. they don't always split at the seam. it has to be removed completely to deal with it. you could possibly reglue it if you could find a glue that actually dissolved the plastic in order to provide a good bond, or just put on a new one like most folks do.

crap I was afraid of that ! I can't find airboxes anywhere... Source ?

I have a complete, intact pre-EGR air box with uninstalled pop-off valve for $85, shipped, if you're interested.

Could try this Plastic welder for $29.... http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41592

Not sure if the kit comes with filler rods: http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41602

You'll also need a compressor capable of 15 PSI

I had a similar problem with my airbox which blew itself neatly into two halves. I was on a tight budget at the time (two weeks after buying the car!!!!!) and so did a self repair. I used a high temperature liquid engine gasket and some slightly larger screws and kept my fingers crossed. It lasted 4 years before it started to leak. Give it a go, you will only waste a little time which can be quite cheap. It is also rewarding when it works.

Good luck
Ian

Did you drop the motor to get to it Ian ?

I am a bit surprised the car would run so well with a split box, but then again I am missing those screws, so it's strange !

There's some good advice, for a quick fix. A temp regulated soldering iron works just fine too.

Epoxies will NOT work worth a damn on these boxes.

Solvent based aren't likely to work well either. (though I've never tried . . but i'm guessing the base plastic is too crystaline to have this work. ...elevated temp solvent-bonding is the work-around there)

I just took a look at my 1973.5 CIS car that is running just fine.

The hole you circled on mine does not have a screw in it so I figure you should just leave it alone.

I have had several instances of the idle hunting. A trip to my wrench and few minutes on the exhaust analyzer and I was back in the saddle.

FWIW, with the air cleaner off, there is a noticeable "Whoosh" in my car. Coul dit be that it is just the "CIS Sound". I noticed my car quieted down considerably when I took the K&N Filter off my car and replaced it with a paper element.

85 bucks is a wicked good price for a box. I'd jump on it.

Otherwise scrap the junk.

I'm with Brother on this one even though I repaired mine. It's a lot cheaper than we would see on this side of the pond!!! Buy it and keep the other one as a just in case.

Ian

Harry,
That whoosh sound is typical for CIS.

Thanks guys... Actually on a trip to warm up the car and set up my idle correctly, the generator light lit up solid. I think the gen/alternator (whichever) is fried, and part of the sound I heard and attributed to the CIS might have been the alt bearings scraping to death. Anyway I still got that CIS problem so now it's back to the shop ! ;-(

I might buy your cracked box if I do go with the tbitz setup.

If it turns out to be the box, you can have it for free... But I won't know until I remove it and that'll be this week end !

Your the man!

Mine was in bad shape when I got it. So I took all the old self tapping screws out and used 8-32 screws and washers with lock nuts on the back side and then used Ultra copper sealant. It has worked for several years I did also install a pop off valve.. I do think however That over the winter I will just put a new one on.. I have checked for leaks with brake clean or carb cleaner everyonce and a while but no leaks works well. You just have to check for leaks then you will know weather or not it works..