Can my airbox be saved?

[clevy70911T]

Heard a backfire into the airbox and removed stuff to investigate. Car has had a cold start problem for the previous owner. Notice the absence of screws holding it together also. The pics look as though the crack between top and bottom pieces is big, but it's not as bad as it looks. Look at the pics and give me advice on if this can be sealed and screws placed where they are missing. Thanks, SCott

[smarjoram]

mine looked a bit like that but when I removed it I found other cracks in the lower part.

I'd say it's be best to replace it - see what the others say.

Also, the screws may have popped out when it split - unless you know they were missing to start with.

[klaucke]

Perfect time to upgrade to Carbs!

[Paulporsche]

It has always been said that the airbox cannot be repaired (although they always said that the WUR had to be replaced until some smart guy figured out how to adjust it). I suppose it's worth a try. Maybe adhesive for ABS plastic will work, or possibly fiberglas resin and cloth. You might get away w/ a thin metal piece bolted to the plastic sealed w/ the same hi temp/hi strength silicone used for the popoff valve.

If you fix it or replace it, make sure you install that popoff valve.

[Hetmann]

My airbox had a hairline crack you couldn't even see. The car ran ok when cold and bad when warmed up. Took me (and my wrench) a long time to find it. Once we replaced the airbox --- problem solved. You might be able to fix yours, but make sure it is air tight when you're done.

[Mark sP]

As above, I would try fibreglass matting.

[john walker's workshop]

test some glues on the flat area inside. let it set, and then try to pop it off. most glues will not dissolve the plastic to make a decent bond.

[jpnovak]

Isn't the airbox a nylon based plastic? In this case there are few glues that will work. Try welding the area with a soldering iron. That should work for small areas. The plastic welding kits could also be used. Of course, I don't know for sure since I don't have CIS on either car.

[osidak]

When my box blew many years ago looked just like that. Started to remove it and I discovered I had two fist size holes in it that I couldn't see before I started to remove it. Replacement part was something like $275. I wouldn't even bother trying to repair it as it is enough of a PITA to R&R it that I wouldn't want to do the job twice.

[Paulporsche]

A plastics supply house may be able to tell you what to use. There are new adhesives available for plastics that were previously not thought to be repaired.

If you come across one that works let us know.

[clevy70911T]

Thanks for all the advice. My car starts hard and then runs ok when warmed up. Idle is high and doesnt pull very hard at full throttle, actually pulls better letting off the pedal somewhat. I knew this car needed some work when I bought it, but replacing the airbox is more than tickering than I wanted. I'll probably try to repair it, assuming this is the only place it is damaged. When I have the engine out, I'll do it right. I'll let you know if I have any luck.
Thanks again, SCott

[azasadny]

I have used two-part epoxy to repair cracks in my airbox and they have held for two years!

[john walker's workshop]

a proper repair, if it's repairable, will require a glue that becomes one with the plastic, by dissolving the contact surfaces, instead of just laying on top.

[clevy70911T]

Thanks. I assume a glue just lying on top would pop out even with a pop-off valve install. If I can just find a glue that will do a vulcan plastic mind-meld with my airbox. hmmm?
Anyone ever consider or know if it's possible to place a one-way valve at the arrow or anywhere else as an temporary alternative to a pop-off valve? I'd hate to install a pop-off and then have to replace the whole airbox anyway. Might be able to cut out the old one and sand the epoxy down and use it again, I suppose. Is it true that the engine has to be removed to replace the airbox? I will anyway as I want to replace all the hoses and such, just wondering if anyone has tried it?

Thanks again! Scott

[clevy70911T]

Here's the pic that I forgot to include in the last post.

[vash]

clevy, use the pop off valve. it is bigger than any one way valve you are suggesting. i thought the same thing before. but once my car pop hard and the POV came off! i guess the pressure was huge enough that the valve couldnt open fast enough or big enough, i found it bouncing around behind the aircleaner. once you change air boxes, i bet you could grab the POV with some pliers and twist it out easy, then just remove the old glue and install into the new airbox. (or the used part will already have one). in my opinion, you need a new one, the best fix would be to do it from the inside. and that would be hard. do it once, do it right. i swear, i think i read a thread where some dude changed it out with the motor in the car.

[clevy70911T]

Pop valve has been ordered !

[mb911]

You know I have thought about making some these boxes out of Stainless steel. Maybe its time! I don't think many replacements are still around. I could then offer SS mufflers and the airboxes! I am thinking out loud. I fixed my air box (when purschsed) with whats called plastic surgery. It melts the bases together worked well. I also replaced all the screws and used bolts with nuts instead. good luck

Ben

M&K Speacialties
Custom exhaust

[osidak]

It can be replaced with out dropping the engine. A partial drop would make things easier but dropping the engine makes it a lot easier.

They made some metal boxes at one point.

[mb911]

Yeah I had a 74 2.7 that had an aluminum box. I just thoght ss would be nice and could be fabricated very easily

Ben