Advice for fixing a dent and crack

Honest John Back Room » Technical matters
What is life like with your car? Let us know and win £500 in John Lewis vouchers | No thanks
View Threaded
Mon 5 Feb 2024 18:36
Advice for fixing a dent and crack - Beardy_J
Hi,

My Suzuki Swift has a dent and some cracks on the rear passenger side wheel arch. The repair quotes I got ranged from £400 to £1000, which is way too much for an old car like this.

I want to cover up the dent and cracks as best as I can, just for my own satisfaction. I have taped it up to hide it, but it looks terrible and I hate looking at it.

I have no idea how to fix the dent myself or take off the bumper. I attempted to use a plunger and suction cups to remove the dent, but they were useless.

So, is there a putty or filler that works by applying it directly over the dent and cracks, without having to remove any paintwork, letting it dry, then sand it down to shape it and then spray paint it? I ideally want something that’s really simple to use and won’t come off when I fill up the dent. I know it won't be flawless, but I just want it to be less noticeable from a distance.

Edited by Beardy_J on 05/02/2024 at 18:40

Reply | Report as offensive | Link
Mon 5 Feb 2024 18:57
Advice for fixing a dent and crack - catsdad

If you can’t polish damage out with a minimum of filler then it’s a job for the professionals. Don’t even think about spray cans. It will only look worse.

My suggestion is to either bite the bullet and shell out for a professional repair or just live with it, assuming it’s not an MOT failure for jagged edges.

Reply | Report as offensive | Link
Mon 5 Feb 2024 19:03
Advice for fixing a dent and crack - elekie&a/c doctor
DIY body / paint repairs are rarely successful. Usually end up looking worse . Leave it to the professionals .
Reply | Report as offensive | Link
Tue 6 Feb 2024 09:43
Advice for fixing a dent and crack - Andrew-T
I have taped it up to hide it, but it looks terrible and I hate looking at it. I have no idea how to fix the dent myself or take off the bumper.

I suggest that 'taping it up' might look little better than the damage, and may encourage corrosion underneath. At least ask the bodyshop what needs doing in detail, and if you don't want to pay, live with the appearance - look the other way ... :-)

If the car is as old as you suggest, taking off the bumper may be for the professionals too !

Reply | Report as offensive | Link
Tue 6 Feb 2024 13:09
Advice for fixing a dent and crack - galileo
I have taped it up to hide it, but it looks terrible and I hate looking at it. I have no idea how to fix the dent myself or take off the bumper.

I suggest that 'taping it up' might look little better than the damage, and may encourage corrosion underneath. At least ask the bodyshop what needs doing in detail, and if you don't want to pay, live with the appearance - look the other way ... :-)

If the car is as old as you suggest, taking off the bumper may be for the professionals too !

if there are any ' mobile dent repair' or 'chips away' guys in your local area they may be a bit cheaper than a body shop, years ago one did a pretty good job on a bumper sc***e for me.

Reply | Report as offensive | Link
Wed 7 Feb 2024 11:59
Advice for fixing a dent and crack - Beardy_J
Thanks for all your replies.

I still think I’ll give it a go myself. As I mentioned I don’t really care if it does look a bit out of place. I just want to fill it up so it doesn’t look as broken and crooked as before.

I’ve heeded your warning to go to a pro but due to the age of the car I may just do the best I can with a filler and spray paint. I just wanted to get some suggestions on whether someone has a recommendation on the best putty/filler to use.
Reply | Report as offensive | Link
Wed 7 Feb 2024 12:18
Advice for fixing a dent and crack - Gibbo_Wirral

Go for it!

Plenty of videos on Youtube - especially with Edd China off Wheeler Dealers.

But the reality is that its a time-honoured skill and our amateur results will never look as good.

Personally I used to use Ispon fillers back when I had a Mini with many rust holes!

Another approach - contact local colleges that do motor apprenticeships - you might find a skilled student willing to have a go for experience.

Edited by Gibbo_Wirral on 07/02/2024 at 12:19

Reply | Report as offensive | Link
Wed 7 Feb 2024 12:28
Advice for fixing a dent and crack - Andrew-T

Personally I used to use Ispon fillers back when I had a Mini with many rust holes!

Good grief - Isopon ! Forgotten all about that ...

Reply | Report as offensive | Link
Wed 7 Feb 2024 19:39
Advice for fixing a dent and crack - up north

You could first find out from those who wrap cars the cost of doing something basic with both rear wheel arches and above, nothing fancy and similar colour to car. All you would need to do is fill in sand and prime to get a nice flat surface then the wrap will cover. Might not cost much for the 2 wheel areas if you stick to a minimal area as a bonnet is £125

Reply | Report as offensive | Link
Wed 7 Feb 2024 20:42
Advice for fixing a dent and crack - Adampr

Incidentally, if it's a metal.wheel arch, you can take the back wheel off, remove the wheel arch liner and bash the metal back out with bell pein hammer wrapped in a cloth. You won't get a perfect result by any means, but the less filler you use the better.

Reply | Report as offensive | Link
Wed 7 Feb 2024 21:36
Advice for fixing a dent and crack - catsdad

Good idea Adam if the OP has the skill.

If not it could be a case of “I know an old lady who swallowed a fly”

Reply | Report as offensive | Link
Wed 7 Feb 2024 23:18
Advice for fixing a dent and crack - Andrew-T

Incidentally, if it's a metal.wheel arch, you can take the back wheel off, remove the wheel arch liner and bash the metal back out with bell pein hammer wrapped in a cloth.

Surely there will be a double skin there ?

Reply | Report as offensive | Link
Wed 7 Feb 2024 23:56
Advice for fixing a dent and crack - Adampr

Incidentally, if it's a metal.wheel arch, you can take the back wheel off, remove the wheel arch liner and bash the metal back out with bell pein hammer wrapped in a cloth.

Surely there will be a double skin there ?

There wasn't on the last car I did it on.

Reply | Report as offensive | Link
Thu 8 Feb 2024 09:52
Advice for fixing a dent and crack - Andrew-T

<< Surely there will be a double skin there ?

There wasn't on the last car I did it on. >>

Where the inner metal arch meets the outer skin ?

Reply | Report as offensive | Link
Thu 8 Feb 2024 13:22
Advice for fixing a dent and crack - bazza

It is possible to do a decent job yourself particularly on an older car, but you need to take your time and watch many YouTube videos. They make it look easier than it is. I've done several decent repairs good enough to pass unoticed except by experienced eyes. Buy the proper materials, take your time, choose a dry day and invest in a hot air gun or old hai dryer. Make sure you buy good quality paint aerosol matched to the colour code of your car, plenty of suppliers online. Good luck, it's very satisfying to do!

Reply | Report as offensive | Link
Fri 9 Feb 2024 00:32
Advice for fixing a dent and crack - edlithgow

One snag with this kind of cosmetic repair, using polyester filler, is that it tends to encourage corrosion long term (if there is a long term) because the stuff uses a talc (?) filler which absorbs moisture and holds it against the metal where its paint protection is already probably compromised by impact damage.

My last car had some shallow body filler (almost certainly professionally applied) on one wing which was rust jacking the paint. After picking it off and abrading the underlying rust with aluminium, (with sunflower oil as a binder), no further problem, (apart from cosmetically, which wasnt a problem to me.) If left it would have holed eventually.

I suppose this could be minimised by using something impervious to seal the metal first, either a conventional primer or, better, an epoxy, which is less likely to give adhesion problems with the filler, but I'd bet this is seldom done. If using conventional primer it would have to be thoroughly dry before applying filler.

I havnt really done cosmetic repairs though, unless you count successfully reconstructing a rotten Lada chassis outrigger from the inside with ferrocement to get it through a few MOTs,

I'm assuming your repair is to steel, though "cracks" might imply plastic, in which case corrosion isn't an issue, though adhesion might be

Edited by edlithgow on 09/02/2024 at 00:36

Reply | Report as offensive | Link
Fri 9 Feb 2024 04:44
Advice for fixing a dent and crack - edlithgow

Oh and re-forming the (horrible rot-trap) of a Marina inner wing with fibreglass.

I formed the shape first by back filling and carving lightweight vermiculite "bonding plaster" (or maybe "browning":Cant remember the correct builders terms now) which I mostly knocked away from the inside after the fibreglass had set.

Underseal hid the glasswork somewhat, but the tester might have been distracted by my slightly unconventional fabwelding of both body box members and outriggers (NOT cosmetic) , which he felt obliged (and somehow entitled) to hit with a BFH (rules, what rules?) until he got tired.

Edited by edlithgow on 10/02/2024 at 01:14

Reply | Report as offensive | Link
Fri 9 Feb 2024 10:57
Advice for fixing a dent and crack - Beardy_J
Hi , thanks for your response. This is the kind of advice I was after.

My bumper / wheel arch is plastic. So do you have any advice on which filler is best for plastic that will adhere properly.

Thanks!
Reply | Report as offensive | Link
Fri 9 Feb 2024 14:35
Advice for fixing a dent and crack - bathtub tom

I've seen dents in plastic pushed out by applying heat. A hair dryer will probably suffice, but iI understand it's more effective if done as soon as possible after the dent was created.

Reply | Report as offensive | Link
Sat 10 Feb 2024 00:53
Advice for fixing a dent and crack - edlithgow

Heat reformation, as already suggested, is probably your best repair technique, though if cosmetics bother you scouring the sc***pies for an undamaged replacement might be your best bet overall.

There are plastic welding techniques. I dunno if they are a DIY proposition (worth doing a Youtube trawl, perhaps) but it might be worth getting a quote from a specialist.

Epoxy is likely to give the best adhesion, and you could use an epoxy adhesive (or superglue) on cracks where the sides are in contact.

You can also "stitch" cracks together using wire, nylon monofilament, cable ties, etc, If the Frankenstein look doesn't appeal, and the crack is going to be visible, you can put self tapping screws on the inside on both sides of a crack and tie between them.

"Stitch and glue" ( a boat building technique used on the Mirror dinghy) involves stitching then (polyester or epoxy) fibreglass taping the back of the crack then flush cutting the stitching and hole filling on the pretty side. This might work with gaffer-type tape, maybe that Gorilla tape stuff, though I have no experience with that.

If you end up using polyester filler (I dunno if epoxy filler is readily available in quantity and if it is it'll probably be quite expensive) to fill a dent, you can improve adhesion by drilling holes in the plastic and optionally putting self tapping screws in if the heads will be below the level of the filler.

It'll take time, skill and luck to get such a repair to look OK though. If it does, but its fragile, you could perhaps reinforce it with a layer of fibreglass on the inside

Best bet with large repairs of that kind is to make a sacrificial mould of the outside contour (perhaps off an intact example) and then lay up fibreglass from the inside, but thats really only worth doing for something like a boat hull

If you use epoxy avoid skin exposure. You can get a nasty and long lasting sensitisation reaction to epoxy

Edited by edlithgow on 10/02/2024 at 01:21

Reply | Report as offensive | Link
Mon 12 Feb 2024 01:24
Advice for fixing a dent and crack - edlithgow

DIY plastic welding, using a soldering iron, looks to have potential, providing your bumper is a thermoplastic, (easily tested) and you can get electric power to it.

The thermal wire stitching shown, in particular, looks to be quite practical, assuming the videos arent faked. I'd probably favor stainless or copper wire, since the staples shown seem likely to rust quickly.

I'm a bit doubtful that cable ties (which I think are nylon) would be much good as filler rod, since the bumper is likely to be a different plastic. Perhaps the best filler source would be a shaving from a hidden part of the bumper, or from a broken one of the same type.

You might not get an acceptable surface finish using these techniques, even sanding with wet and dry paper, so might still have to fill repaired cracks with polyester paste or another filler. Allegedly superglue filled with baking soda, portland cement or charcoal dust works, and might be of use if you dont need very much, especially, in the latter case, if the plastic is black.

I have used highly compressed crumpled aluminium foil wetted with sunflower oil (leftover from rust treatment) to fill a small hole. Set hard and was sandable, but I've only done it once, and I suspect it wouldn't be reliable in most locations.

Perhaps try a flat iron as a heat source when attempting to correct dents.

If buying a soldering iron I would go for the most powerful one you can find, since they often dont seem to get hot enough, though that might be because I cant solder.

www.youtube.com/watch?v=yjr5LT6uUGs

www.youtube.com/watch?v=ZuuBctx-l9M

Lots more "instructional" videos out there, though I'd take them with a pinch of salt, as a basis for your own experimentation.

The one below is a different technique, using solvent dissolution of plastic to make a glue/filler. I have experimented with this a bit, and I found the polystyrene "snot" produced had rather poor adhesion. I might have used white spirit as a solvent though, (cant remember) which is maybe inferior to acetone.

Most solvents will destroy the rubber seal on a syringe plunger, so using one as shown in the video you'd have to be rather quick.

www.youtube.com/watch?v=wq0_uLgWo5g

Edited by edlithgow on 13/02/2024 at 01:48

Reply | Report as offensive | Link