Gluing/repairing small plastic strap

[Skylark]

There’s a plastic strap fitted around the oil filler cap to prevent it going astray when topping-up. In section, it is very similar in size and profile to a cable tie. Mine has broken in two, approx in the middle of its span (non boaty). It is 35 years old and a replacement is not available.

I’m planning to repair it by gluing a section of cable tie (say 20mm long) over the broken join, then electrical cable heat shrink over the joint (say 40mm long). It is not load bearing but sees engine vibration and a heat cycle.

Yesterday evening, I tried gluing two sections of cable ties together as a test, one sample using epoxy and the other with superglue. I used emery cloth on all surfaces.

Neither test has been particularly successful. The epoxy sandwich joint easily pulled apart. The superglue was better but I could still open the joint without much difficulty. Will the heat shrink help? Probably.

Any other ideas? Many thanks.

 

[fredrussell]

Not much will stick to certain plastics. HDPE and LDPE if memory serves. 3M do a glue for these but it’s expensive and needs a bespoke applicator ‘gun’.
What about melting them together?

 

[Mister E]

Your best bet is some strong twine and tie it the the cap and the car fuel filler section.

 

[Daydream believer]

I would suggest cutting most of the old plastic strip away. Leave a little bit of "meat" behind. ie do not cut completely back flush. Then using a fine drill, carefully bore a hole through the 2 stub ends. Through these holes insert some whipping twine. If you can find a friend with some dynema fishing braid that may be better, but whipping twine should do the job OK

 

[Skylark]

Wow, that was quick, thanks to you all.

I was thinking about getting a soldering iron out, maybe I’ll try it first on another cable tie.

I also considered strengthening the glued joint with a whipping twine stitch.

Do you guys think that the heat shrink will help?

The plan is to make the repair look as close as possible to original.

 

[KevinV]

I've found 1mm stainless wire, ferrules and pliers to be invaluable to have around for this kind of thing - you can make any retaining strap you need. As above, a piece of string will achieve much the same, just not as neatly.

I doubt that anything will successfully glue age hardened and oil soaked plastic of any variety.

 

[Skylark]

Removed the part and discovered that it’s rubbery so now hope of gluing it back together ?
I’ve used two sizes of heat shrink and it looks ok but not now expecting it to last. Maybe find something during the summer car show season.
Thanks for all of the useful suggestions.

 

[andsarkit]

Adhesive lined heatshrink will probably work along with the parallel cable tie. If you also cut some very small notches into the original strap and have the serrated side of the cable tie outwards the glue will fill all the hollows. The end result will be rather stiff so it is best to select a size of heatstshrink just large enough so that the wall thickness does not increase too much.

 

[billskip]

Removed the part and discovered that it’s rubbery so now hope of gluing it back together ?
I’ve used two sizes of heat shrink and it looks ok but not now expecting it to last. Maybe find something during the summer car show season.
Thanks for all of the useful suggestions.

View attachment 148523

Cant you make a new one out of an old inner tube?

 

[Mistroma]

I was going to suggest covering with heat shrink after gluing, especially if you have the type with adhesive inside.

Try the following with low viscosity superglue that's pretty much like water.

1. Cut back a pencil lead and rub it on a fine file above a sheet of paper, repeat until you have a small pile of graphite powder.
2. Mix the graphite with an equal amount of baking soda.
3. Slip some shrink wrap over the plastic strip well clear of the joint and lay the 2 pieces on some greaseproof paper.
4. Line up the join and use weights to hold the bits in position
5. Wet the joint and either side with some superglue and sprinkle a small amount of the graphite/baking powder mix on top
6. Repeat if you want to build it up a little, turn over and repeat on the other side
7. Smooth off with some sandpaper, slide the heatshrink into place and heat carefully.

It should form an immediate strong bond as the superglue cross-links through the power substrate. It will probably bond to the greaseproof paper and you'll need to clean that up with a blade before repeating with powder on the other side.

Let me know if that works, it should be several times stronger than neat superglue and sets instantly, no need to wait 30-60 seconds. You could do a test first with a couple of cable ties. I've used it on similar material but never on cable ties.

 

[VicS]

Removed the part and discovered that it’s rubbery so now hope of gluing it back together ?
I’ve used two sizes of heat shrink and it looks ok but not now expecting it to last. Maybe find something during the summer car show season.
Thanks for all of the useful suggestions.

If it is a synthetic rubber (neoprene or nitrile but not silicone) a cyanoacrylate adhesive aka "super glue" should do the trick,
but degrease the surfaces thoroughly first.

 

[Skylark]

Some very interesting additional comments, many thanks to you all.

The material is not what I expected it to be. It’s not at all like a cable tie, it’s is rubbery and hardish, not as soft and supple as an inner tube. When I pierced it with a very sharp needle it split.

For now, I’m reasonably content with the application of double heat shrink (not the +adhesive version). The car in question only does a max of a couple of hundred miles per year so the joint repair should not be stressed.

Notwithstanding, I may put a drop or two of superglue on its surface, cleaned and sanded, to see what happens……..

 

[VicS]

Some very interesting additional comments, many thanks to you all.

The material is not what I expected it to be. It’s not at all like a cable tie, it’s is rubbery and hardish, not as soft and supple as an inner tube. When I pierced it with a very sharp needle it split.

For now, I’m reasonably content with the application of double heat shrink (not the +adhesive version). The car in question only does a max of a couple of hundred miles per year so the joint repair should not be stressed.

Notwithstanding, I may put a drop or two of superglue on its surface, cleaned and sanded, to see what happens……..

Perhaps after 35 years it is past it's "use by date" It may not be worth trying to repair it. I don't think I've ever had an oil filler cap on a tether and I have not lost one yet.

 

[billskip]