Help Please Fuel Cap

[fortuner]

Hi guys my moms car the fuel cap they broke or split the part ...Dont ask me how lol.

Ill try to put some photos .

Its the fuel closing lid the plastic has been broken i need to fix it as to replace ia like 150 quid only the part.

Can anybody advise me whats best way ro fix it myself or what atmrw suggestions i want ti to be done in a way it wont be noticed and will work..

Superglue ?

 

[fortuner]

 

[Matski]

I'd give styrene cement a go - kind of thing one might use in airfix kits.. I believe it's likely to be a less brittle bond than cyano acrylate based superglues... it's all about the direction in which forces will act on it.

All superglues are not equal though, so it could be hit or miss either way.

I'm not an expert in liquid based curing adhesives though, so I could be wrong.

 

[Giannis]

Either a good two-part epoxy type glue will work or you'll have to get a new part.

Super glue, contact cement, duct tape, etc, just don't work.

 

[Matski]

Either a good two-part epoxy type glue will work or you'll have to get a new part.

Super glue, contact cement, duct tape, etc, just don't work.

Certainly not questioning your statement, but out of curiosity, is this based on experience or science?

I know "duct" tape won't work (rubber based adhesive... pfft), but I had the impression something like styrene cement literally fuses ABS plastic (which I'm guessing it what that part is) together. Where as cyanoacrylates stick like f*** their internal strength is "delicate"... And I thought 2-part epoxies were only better because their curing mechanism makes them a little more resistant to exposure, rather than the bonding strength being better...

... wow... that's maybe the most boring paragraph I've ever typed!

 

[Giannis]

Certainly not questioning your statement, but out of curiosity, is this based on experience or science?

I know "duct" tape won't work (rubber based adhesive... pfft), but I had the impression something like styrene cement literally fuses ABS plastic (which I'm guessing it what that part is) together. Where as cyanoacrylates stick like f*** their internal strength is "delicate"... And I thought 2-part epoxies were only better because their curing mechanism makes them a little more resistant to exposure, rather than the bonding strength being better...

... wow... that's maybe the most boring paragraph I've ever typed!

Experience.

I've got zero knowledge on how each adhesive works and how it combines with each type of plastic. I'm completely clueless.

But over the years, I've broken various plastic bits and pieces of my Clio, and I'm too much of a cheap ass to go buy replacement parts.

For contact cement, I've only uses a cheap one I found in a local hardware store. While it looks like it works, it won't take much of a beating. The same goes for epoxy, but with epoxy you can create a much thicker layer and take advantage of the epoxy's strength as a separate material.

A couple of examples that come to my mind. I broke one plastic bushing that supports one part of the passenger's seat head rest. Superglue worked fine for a weekend, contact cement worked fine for a couple of months, but when I epoxy'ed the @#$% out of it, it never broke again. Same experience with the plastic holders for the wheel nuts wrench.

On the other hand, I might just be so clueless that I used the wrong type of cement or glue.

 

[Giannis]

Sidenote:

The door panels of my Clio are made of hardboard. The worst possible quality. A few years back they cracked where your elbow rests. I tried to fix the first one with polyester and fiberglass. The result was mediocre. I tried to fix the second door with white glue and newpapers. It somehow worked better than the first.

For the other two doors, I removed the damaged hardboard and used some high strength, fiber reinforced, cement based repair mortar that I spared out of a construction site I worked. Apparently, those parts are now tougher than the car's steel chassis.

 

[Matski]

Experience.

I've got zero knowledge on how each adhesive works and how it combines with each type of plastic. I'm completely clueless.

But over the years, I've broken various plastic bits and pieces of my Clio, and I'm too much of a cheap ass to go buy replacement parts.

For contact cement, I've only uses a cheap one I found in a local hardware store. While it looks like it works, it won't take much of a beating. The same goes for epoxy, but with epoxy you can create a much thicker layer and take advantage of the epoxy's strength as a separate material.

A couple of examples that come to my mind. I broke one plastic bushing that supports one part of the passenger's seat head rest. Superglue worked fine for a weekend, contact cement worked fine for a couple of months, but when I epoxy'ed the @#$% out of it, it never broke again. Same experience with the plastic holders for the wheel nuts wrench.

On the other hand, I might just be so clueless that I used the wrong type of cement or glue.

Fair enough, never a bad idea to go with what you know

 

[Gianclaudio]

@Matski styrene glue will only work for styrene and ABS (a styrene too) parts.
@fortuner you should check what kind of plastic the piece is made of....most modern cars have every single plastic piece with a recycle logo cast on them, telling which kind of plastic it is (pp, pe, ps, etc)

Bear in mind some plastic like polyethylene, nylon and polypropylene can't be glued with anything, not even epoxy or super glue

 

[Matski]

@Matski styrene glue will only work for styrene and ABS (a styrene too) parts.
@fortuner you should check what kind of plastic the piece is made of....most modern cars have every single plastic piece with a recycle logo cast on them, telling which kind of plastic it is (pp, pe, ps, etc)

Bear in mind some plastic like polyethylene, nylon and polypropylene can't be glued with anything, not even epoxy or super glue

For some reason I had it in mind it would be ABS or HIPS.. but thinking about it, it's probably Polyamide/Nylon. @fortuner if it's Nylon it'll say PA-xx on it somewhere.

If you want to read some boring stuff on it.. Bonding Nylon | Industrial Adhesives | Polyamide Surface Preparation

@Gianclaudio LSE plastics like PP and PE can be tricky for consumer grade adhesives, but in industrial applications it's entirely do-able. I buy several tonnes of adhesive bonded PE every month I could tell you how, but then I'd have to kill you

 

[fortuner]

Thank you all for your advise and help..

On a side note I am more confused lol.

 

[Matski]

Thank you all for your advise and help..

On a side note I am more confused lol.

If Giannis has had positive results with 2 part epoxy, I'd give that a go. Araldite standard would be the kind of thing, should find it in any Homebase store, or similar.

edit: don't attempt to rough the surfaces up as it might suggest... with a snapped part you already have maximum contact area. However, make sure both ends of the join are clean and free of any fuel residue, grease, dust etc...

 

[fortuner]

Update i checked the plastic is PBT GF50

@Matski which epoxy sorry First time i am doing this.

 

[Matski]

Update i checked the plastic is PBT GF50

@Matski which epoxy sorry First time i am doing this.

Araldite is a common 2 part epoxy on sale in the UK...

ARA-400001 | Araldite 32 g Tube Epoxy Adhesive | Araldite

It's basically that, you should find it in most hardware shops

Squeeze a bit from each tube, mix, stick...

It's probably as close as you'll get from a retail product.






re-edit: if that doesn't work, the "superglue" route is a little more convoluted, it looks like using Loctite 770 primer first, then Loctite 401 to make the join... both are available online..