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Huge crack appeared!


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Hi all, 

 

Some of you may remember I posted earlier this year about the paint coming off on top of the rear plastic end of our van (2015 Elddis Avante). 

 

We know the previous owner (or the one before that) had it repaired due to water ingress, and I suspect it relates to that in some way.  The white paint seemed to bubble/flake off and expose the green plastic underneath. 

 

At the time, I covered it with white Gorilla Tape which is waterproof to protect the plastic from rain & UV.  It's actually held all this time, but we were away this weekend when the rain hit and we noticed signs of water on the rear bathroom ceiling, all along the back wall - basically under where the plastic end is joined. 

 

I went up on a ladder to check it when we got home, and (swearing removed) me - there's a right crack appeared under the tape!  No idea what or why - possibly structural weakness caused by the previous repair, the love of speed bumps on Caravan Club sites?  Who knows.....

 

Anyway, I've whipped off the old tape and added more to try protect from water, but we all know what water is like! 

 

Anyway, photo's attached - the grey stripes are the backing from the Gorilla Tape that's been on there for a few months.   I've asked out mobile service guy what he thinks, but given the knowledge of our fellow users here I would appreciate the benefit of your experience. 

 

We have no plans of selling the van yet, so would like to repair it and to be honest, given it's out of sight I don't really care what it looks like as long as it works! 4.jpg.10f9ed4d6277350c88e74540de164988.jpg

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Think theres' a post on here about drilling each end of crack to stop it travelling then welding using acetone and a lego brick-or did i dream it?

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There is a product in use in USA called 'Eterna Bond'. basically a very wide super strong waterproofing tape.  Sort of thing they use to assemble the giant motor home roofs etc.  Well worth researching on tube.  It is available on eBay in the uk I believe.

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My suggestions:

Clean tape residue off with suitable solvent.

Use:

https://www.rooflock.com/rooflock-tape-high-performance-waterproofing-tape/

Can be got from:

https://www.ebay.co.uk/itm/274082839662?var=574235293304

Which is not just "sticky tape" it appears identical to Eternabond (USA, plenty of You Tube video but suppliers on Amazon may be suspect?)

Main problem will IMHO be where end panel joins body at the bar on the top so perhaps seal this as well?

As you say, it can't be seen from ground level and can easily be checked regularly.

Whilst I've also seen the ABS Goo trick, a suitable tape will perhaps give a far better seal and with correct preparation be a speedy and good repair which I'd be happy with?

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I had exactly the same thing happen on my last van, looking at your picture it certainly looks like the crack has propagated from the join where the strip is, likely caused because during manufacture where they should drill pilot holes for the screws but have not and instead have just screwed straight through the panel which over time will cause a stress crack which just gets bigger and bigger.
 

Definitely worth drilling a small hole right at the end of the crack as this will stop it from propagating any further.

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I would suggest hot metal stapling....either buy your own kit, or use professional repairer.... the trouble with the lego brick repair, its joins the top side only..repair will not last....

https://www.ebay.co.uk/itm/382816014631?epid=13017014702&hash=item59219cd127:g:hbsAAOSwhQhY3oQC

Edited by gtepete
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I would simply put a large patch over it, but one specifically bonded with a quality polyurethane bonding agent like one of the Sikaflex products. I am thinking about a 6" odd wide patch.

Importantly,  ensure the bond is of substantial thickness, this is not a squeeze it out task but one where you need a minimum of 2 mm thickness. [achieve this by using a few temporary spacers, say pieces of a polythene rod, something that will not bond and can be pulled out after the Sikaflex cures, then filled]

The reason thickness is need is to accommodate  all the flexing without breaking the bond. The same flexing will ultimately fail un reinforced plastic solvent "welded",  "repairs"; compliance is need.

 

Obviously all the required surface cleaning preps must be done before bonding is attempted.

As others have said, drill a decent hole right at the running end of the crack in an attempt to relieve point stressing , 6 mm odd.

 

 

Edited by JTQ
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Bless you all, thank you! 

 

I thought I should drill a hole but it's a bit daunting to do it without reassurance first! 

 

Will look into everything properly and update you all. 

 

Thanks again 👍🏻

50 minutes ago, DougS said:

My suggestions:

Clean tape residue off with suitable solvent.

Use:

https://www.rooflock.com/rooflock-tape-high-performance-waterproofing-tape/

Can be got from:

https://www.ebay.co.uk/itm/274082839662?var=574235293304

Which is not just "sticky tape" it appears identical to Eternabond (USA, plenty of You Tube video but suppliers on Amazon may be suspect?)

Main problem will IMHO be where end panel joins body at the bar on the top so perhaps seal this as well?

As you say, it can't be seen from ground level and can easily be checked regularly.

Whilst I've also seen the ABS Goo trick, a suitable tape will perhaps give a far better seal and with correct preparation be a speedy and good repair which I'd be happy with?

This is great DougS, thank you.

 

I think I will drill, sand and fill the crack. Also dig out the sealant under the bar so the tape can go under it a bit, then re-seal the bar over the top of the tape. 

 

That's my thought process at the moment anyway!

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As GT Pete says, as well as drilling a hole to stop the crack propagating, it also needs the broken edges bringing together, aligning and stabilising , before filling, it appears appears that there is a difference in height of around 5+mm at least, if this is simply filled, the crack may well appear again due to the nature of the van body flexing whilst moving.

 

With all filling operations the most important aspect is preparation, removing all grease, polish, tape glue and clean the surface well etc.

 

Another important thing is to ensure that the filler used is suitable for the plastic, not all fillers are suitable for all plastics.

 

Given that the plastic roof is self coloured white,  ( see the edge of the crack) I'm intrigued  as to what the ' green plastic ' is, it could well be plastic primer / adhesion promoter used to ensure that the paint coats, primer, colour and lacquer, when needed, bonds well to the plastic.

 

What is more interesting is that the green colour appears to have , dribbled, travelled down the split edge, as can be seen prominently near the rail end, less so at the opposite end of the crack, which suggests that the crack was already there when the green compound was applied and has travelled further since.

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1 hour ago, Silversurf said:

As GT Pete says, as well as drilling a hole to stop the crack propagating, it also needs the broken edges bringing together, aligning and stabilising , before filling, it appears appears that there is a difference in height of around 5+mm at least, if this is simply filled, the crack may well appear again due to the nature of the van body flexing whilst moving.

 

With all filling operations the most important aspect is preparation, removing all grease, polish, tape glue and clean the surface well etc.

 

Another important thing is to ensure that the filler used is suitable for the plastic, not all fillers are suitable for all plastics.

 

Given that the plastic roof is self coloured white,  ( see the edge of the crack) I'm intrigued  as to what the ' green plastic ' is, it could well be plastic primer / adhesion promoter used to ensure that the paint coats, primer, colour and lacquer, when needed, bonds well to the plastic.

 

What is more interesting is that the green colour appears to have , dribbled, travelled down the split edge, as can be seen prominently near the rail end, less so at the opposite end of the crack, which suggests that the crack was already there when the green compound was applied and has travelled further since.

Wow! Go Sherlock!! 

I assumed that the green was the base colour of the plastic but yes I can see it's white under the green.

 

The person we bought the van off was a bit hopeless so didn't know exactly what the problem had been, other than it had leaked and the rear end needed to be repaired.

 

Any suggestions on how to bring together both sides of the crack?  Perhaps the heat stapler suggested previously  although the cost is a bit scary for a one off use! 

 

I've ordered some Milliput which seems to be suitable for plastic and was planning on using the dremmel to gently create a 'V' along thencrack to give the milliput something to stick to.

 

But yes, unless I can get the uneven sides together first then I can see any repair not lasting too long.

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I am far from convinced why one would want to " bring together" the sides of the crack, they are moving to relieve the stresses, why reinstate stresses, the more so now in aged ABS?

 

It cracked in the first place because of stressing, as all cracks do.

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Maybe use some aluminium straps across the crack and self tappers while glue is setting, then remove and fill the screw holes?

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Just now, gtepete said:

Maybe use some aluminium straps across the crack and self tappers while glue is setting, then remove and fill the screw holes?

 

No, whatever you do, don't use self tappers. These work by forcing themselves into the plastic.

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Maybe not a good idea to introduce more holes in the roof....

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As has been said the crack emanates from under the sealing strip but may not be caused by a screw hole.

First thoroughly clean the are removing all old tape etc.

Depends on your diy skills but if mine i would buy some thin stainless steel mesh (halfords sell it I know) used in car body repairs. Cut a band to cover an area 1cm either side of the crack. Drill a stop hole at the end away from the sealing band and, having re-aligned the two edges heat the mesh with a soldering iron and melt the mesh into the panel either side of the crack and finish as best you can and then rub down the repair to flatten it. Purchase a sheet of 2mm thick abs plastic from a local plastic supplier (mr plastics are Norwich based and you can buy online) and cut a ‘patch’ from the plastic sheet large enough to comfortably cover the crack/repaired area, ensuring the area under the patch is abraded on the patch and the panel and then fixing it in place with a layer or your favourite sealant applied and spread evenly on underside of the patch (i prefer Soudal Fix-All but Sikaflex wd be fine).

This repair is doable and strong but only attempt it if you are confident.

Edited by VOLVOVANNER
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Don't think clearing and filling the crack is any use.

 

I quite like the mesh idea with a plastic plate glued on top. Whether to use a plastic bonding glue (lacking flexibility) or something like Bostik Simson ISR-03 or STR 360 am not sure.

 

But you may as well give it a go.

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However you end up repairing it/getting it repaired I endorse the suggestions that involve:

  • A hole at the end of the crack (10mm would be a good size to achieve long lasting stress relief and drilled just after the crack becomes too small to see - deformation/weakening may be ocurring which you can't yet see.
  • Not trying to close the crack.
  • Fitting a repair panel over made of the same material of similar thickness (to avoid differential expansion). I wouldn't be against using stainless self tappers to hold the panel along with appropriate mastik, but would strongly advise generous pilot holes and heating the screws just before your drive them home. This will soften the plastic and avoid stress cracks.
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OK  small progress update (and thanks for the continued feedback, it is all helping!)

 

The sun is shining, so I've removed the tape and cleaned the entire surface. I've removed as much of the bubbled pain at possible and sanded it all down. 

 

To be fair the seller, they probably weren't aware of what had been done, but now I've got it all cleaned up it seems to me that this is a repeat of an earlier crack.

 

If you look at the attached photo you can see at the end of the crack what looks like the remains of two filled holes?  

 

I preferred the option of seal, fill and repaint but the recent comments regarding movement seem to be supported by the new evidence that this is a repeat crack, so if it HAS cracked twice then it seems daft to do repeat what has already failed. 

 

I didn't fancy the idea of a "patch" as it could affect resaleability eventually (?) but thinking now that might be the sensible option. 

 

20211006_111211.jpg

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1 minute ago, mimo said:

This may be of use 

 

 

Hi Mimo, 

 

Funnily enough I watched that video this morning - but thank you anyway! 

 

I've come across this post on the forum from several years ago, and wondered if it was a possibly solution? I guess the problem is I'd be treating the symptom and not necessarily the cause but then again, is a patch over the top just doing the same thing?! 

 

 

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I can't answer that I'm afraid. I've not actually used either method, but I did pay handsomely for a caravan repairer to fix hairline cracks around the window hinges  on the front panel on a bailey 

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The cracks in the video are smaller than your one....I would seriously look at using the stainless steel mesh  method...but ideally the hot staple method.....you could always sell the kit after using it on your roof....

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45 minutes ago, gtepete said:

The cracks in the video are smaller than your one....I would seriously look at using the stainless steel mesh  method...but ideally the hot staple method.....you could always sell the kit after using it on your roof....

 

Hot stapler is on order gtepete ;-)

I'm actually thinking either hot staples or the stainless mesh - is there any reason I can't use aluminium mesh? Seen this on Amazon: https://www.amazon.co.uk/gp/product/B0892T4H27/ref=ox_sc_act_title_1?smid=A1UCQQMVA5Q8Q8&psc=1 and thought it was worth a go?  Perhaps not robust enough?

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I believe the reason for SS mesh is that it stronger than aluminium....not used it myself....but you will need to use a HD soldering iron with a wide foot (tip) to heat the mesh/melt the plastic..

Edited by gtepete
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