Repairing plastic '5 Valve' cover

The good news is that I lucked out and found the '5 Valve' plastic cover that I needed at a local wrecker, and he sold it to me for a good price.
The bad news is that the mounting tabs are broken. Anyone have advice on how to fix them?

In the picture, the one on top (left side cover) should have a screw hole tab on the bottom just like the other one does. No, I don't have the piece that broke off so I'll have to fashion something and then attach it.

Any suggestions?

 

I've not used the stuff myself, but I was told about this stuff which could be used to repair and/or build up plastic pieces; he was using it to repair mounting studs for side covers. It's called Plastex, and it comes with a reusable molding material. You could make an impression of the good mounting hole, move to the broken piece, and use the repair material to fashion a replacement.

In theory, anyway. As I said, I've not used the stuff.

 

The only stuff I know called anything like name, is Plast-X, which is a plastic/plexi/lucite/etc....micro-grit polish.

The stuff that I've used to repair plastic is the Oates ABS Cement. I DON'T know it that will work for this application, though.

However, all is not lost.....I am in the process of trying to do the same repair to a 5-valve cover myself. So, between the few us us we should be able to figure out a way to rebuild the plastic.

Now, that all being said, go to: Hap's site, www.maxim-x.com and look at the repair procedure that he has come up with. I may still be enough for you to run with farther.

dave

 

how about fiberglass and chrome in a spray can

 

Thanks everyone for the tips. Especially hogfiddles for pointing me towards maxim-x.com - I spent a very worthwhile half hour there learning a bunch of things, including the answers to some long standing questions I've had about spark plugs.
I'm going to take my 5Valve cover into Industrial Plastics tomorrow to see what they have to say. I'll keep you posted.

 

Only half an hour?!?!?! LOL

yeah, Hap's got a good site there. You can spend DAYS there, glad you found it useful

Let us know what Ind. Plast. says, please.

CB, I've never found the chrome spray can to actually look like chrome. Looks like brushed silver or aluminum to me........... but that's me.

dave F

 

Make a mold using modelling clay for the tab shape, using one of the existing tabs.

I've repaired many ABS items, including a badly damaged Thule ski box using Lego blocks melted in methyl ethyl ketone (MEK).

Lego comes in many colors, it is possible to get a close match by mixing various colored pieces to achieve the desired results.

I melt the Lego in a baby food jar, takes a day or two to melt to a honey like consistency. It will melt faster if you cut the Lego into smaller chunks with tin snips. I've used fibreglass mesh to strenghten some larger repairs. The repair is usually stronger than the surrounding area.

Be careful with the MEK, very strong smelling stuff.

Dave

 

Lego's!!!!! NICE. I'll put that in my 'remember this' file.

Dave F

 

Update: I went in to Industrial Plastics yesterday and they recommended a plastic epoxy putty called Kwik Plastic from JB Weld. I haven't had great luck with epoxy putties in the past, but I've never used a plastic variety and JB Weld usually makes good products. So I bought it and made some test samples and left them to cure overnight. The samples turned out weaker and brittler than I would like, so I'm going to call that a fail.
Next idea is to use the Kwik Plastic to make a mold off of a good tab and then fill the mold with West System epoxy. Love the modelling clay and Lego blocks method but I don't have those items around the house and I do have West System so I'll try that.

Incidentally, the Industrial Plastics folks said that the 5Valve covers are not ABS but some other, lighter and stiffer variety of styrene. Something to bear in mind when choosing a glue or epoxy to use.

 

Pick up a few shiny washers the correct size and glue them on there with goop. You may have to glue two or three together to get the required thickness. Goop is clear and will stick to just about anything.

 

That, in part, is some of the repair that is on the Maxim-X website.

Dave F

 

So I finally have my tab repaired. Here are some lessons learned:
- JB "KwikPlastik" is too weak to use as a tab repair, and it doesn't adhere well enough to the original piece.
- Wet JB "KwikPlastik" does adhere to fingers, workbenches, etc., to a degree that makes it difficult (but not impossible) to use to create molds.
- West System Epoxy makes a strong tab and sticks great to the original piece, but also sticks to a hardened KwikPlastic mold even if you coat the mold with Turtle Wax.
- A Dremel tool can be your best friend for fixing mistakes.
- Chrome-coloured Duplicolor paint is not nearly as shiny as the cap on the can would lead you to believe.
- I'm reasonably happy with the result, but it was not an elegant process. Next time I'll try the Legos or Plastex as suggested by helpful members.

 

Another lesson learned - when uploading multiple pictures, upload them in reverse order