What to use to repair CIS airbox?

[Hoffmanmotors]

What Should i use to repair a crack in my CIS airbox, Epoxy or JB weld? I have JB weld handy and i have seen it done but what is recommended?

-Jeff

[HarryD]

Jeff,

While I do not know the answer to your question, I will offer to you the fact that JB Weld is epoxy with a filler to help make the joints stronger.

[stlrj]

I would use the JB Weld. Let us know how it works.

[john walker's workshop]

you need something like the original glue which melted the plastic at the joint and then set up as a virtually "welded" joint. JB etc won't do it. it will just lay on the surface. so far i haven't found that elusive glue the factory used. acetone melts regular plastic, ABS plumbing cement melts/bonds with plastic plumbing pipe, but airbox plastic is unfazed by them.

[unclebilly]

The airbox is rotomolded polyethylene or polypropylene - both are olefinic thermoplastics. The only glue that will stick to olefinic plastics is 3M DP8005 or Loctite makes a similar product (3030 I think). You can get this stuff from an industrial supply store such as Acklands or Century Sales - not sure who would supply in the US.

You can use this to glue a polyethelene patch over a hole or a crack. Milk jug material though ugly is a good candidate but anything you can find with the mombius loop and HDPE or PP below it will be fine. ON my 77, the airbox has been repaired with black tape which has held fine since before I bought the car 4 years ago. Otherwise you can weld the air box up which will also be ugly.

[Paulporsche]

Unclebilly,

Did you use hockey stick tape?


(Canada, eh!)

[3.2 CAB]

Dang unclebilly, it sounds like you and my youngest Son, would get along just great. He got his degree in polymer science.

[Porsche-O-Phile]

I'd replace the airbox, but that's just me.

[Matt_West]

I have an air box with a pop off valve available. $40 plus shipping if you want it.

[porsche930dude]

Has anyone tried chyochrylate adhesive not exactly sure of the name but they call it CA glue. Its commonly used by hobbyists and found at hobby stores. Some plastics it has no effect but for the most part it can glue pretty much anything extremely well.

[3.2 CAB]

That is super glue, I am looking at a tube right now. One of its first uses was in the funeral industry, long before anyone ever heard of "super glue" back then, in the very early 70's, it was very expensive, about $12.00 for a 10gram tube. The main reason the funeral homes used it was because it bonds skin extremely well, and lacerations on a face or hand could be closed up, without unsightly sutures showing.

[wowzer911]

"I'd replace the airbox, but that's just me."

Ditto

[Hoffmanmotors]

I have already went ahead and used JB weld, turned out good. I sanded and cleaned the surface so it should be strong. I have a the large port airbox and figure it will be a slight challenge finding another one. If this box fails in the future, im just gunna go ahead and buy PMO's. I always dreamed of doing that anyway.

-Jeff

[unclebilly]

Originally Posted by 3.2 CAB

Dang unclebilly, it sounds like you and my youngest Son, would get along just great. He got his degree in polymer science.

I got a Plastics Engineering Technology Diploma from NAIT back when the program still existed, I wasn't thrilled with the job prospects (the $$$ wasn't great) so I went back to school and got a Mechanical Engineering Degree. The plastics stuff comes in handy every now and then...

I did have some black hockey tape on there for a while but went back to the electrician's tape. I will be putting webers on that car in the not too distant future

[stevemfr]

Originally Posted by unclebilly

Otherwise you can weld the air box up which will also be ugly.

I was going to suggest this - I've even gotten my plastic welds to the point where I can file/sand the surface to the original contour and still have a relatively string weld. Can't get the semi-gloss finish, though.

I'd think (aside from sourcing a cheaper used part) replacement is often too expensive to be easily justified - even for the people who seem to have waay too much money to throw at their Porsches
Aside from that, I'm always interested in quality, low-buck solutions too.

[HarryD]

Originally Posted by unclebilly

.... Otherwise you can weld the air box up which will also be ugly.

Before my current job, I worked in the facilites department of a Semiconductor plan and was responsible for the design and maintenace of a variety of stong acid and base delivery and effluent treatment systems. To prevent corrosion of my systems, we used Poly, PolyPro, PVDF, teflon, kynar, etc. While many of these materials can be weled, the Poly gave us fits until we found out there were two types, linear and crosslinked. We could hot air weld the LINEAR Poly but I have never had any luck with crosslinked Poly.

Do we know what the box is made of?

[roadster49]

Old thread but found this Loctite plastics bonding system and wanted to know if anyone has used it to repair an air box. A major backfire split my air box and am trying to repair.

[roadster49]

[stlrj]

I would try hardware store variety RTV sealer. All it needs to do is seal a vacuum and if it blows up again, there is nothing strong enough to prevent it from going to pieces anyway. Not even a pop off valve.


Cheers,

Joe

[Josh D]

I have used that Loctite plastic bond with good success on smaller items (center console plastic). However, something larger with potential for gaps, I would use a two part epoxy for plastics. I believe Loctite has such a product that I've used successfully as we'll.