HI All,
Wanted to post about my recent win to fix my leaking caravan roof (yes, i know its a car forum, but most of us are vanners so hope this is useful for you).
My Jayco 16.49-3 Expanda developed a small drip on the joint between the roof (aluminium) and end panel (fibreglass), see photos. Unfortunately it dripped on the wife's sleeping bag... oops so needed to fix it.
The old sealant was quite chauky, and was very dirty (it was done by the original owner, say no more!).
I used a scraper (uses single sided razor blades) with brand new blades to remove the old sealant, it was very easy, just a case of getting the right angle (too steep and the razor wants to cut in to the fibreglass, too shallow and you'll leave some sealant behind). The painted surface did not scratch.
The difficult part was the 4mm rebated gap that i couldn't fit the razor blade in (see photos). I spend hours trying to remove it. Then i thought about making my own scraper, so used the angle grinder to cut a razor to 4mm wide to fit in the gap, this worked really well and removed all the sealant very quickly.
Next used sand paper (280grit) to remove any residual sealant and also to lightly scratch up the surface to allow a good bond.
Next i used 90% Ethanol (my local chemist provided a small bottle) to dissolve any old sealant and clean the joint. I think any non residue alcohol will do the job (ie Isopropol, Metho, etc).
I was worried about leaving any residue, so gave the surface a light sand, then brushed the dust way.
Next i masked the area, since the join has 2 x different materials (different expansion rates), i decided to have a nice cap shape to the bead (see last photo), to allow greater flexibility (the wider the sealant, the higher the expansion allowable).
I made up a profile tool, using a old take way container (clear rectangle ones from the Chinese restaurant), and cut a nice radius using tin snips.
I used Sikaflex 221 (Bunnings), and filled up the joint, i used my finger to push up and down (pumping) along the seal to make the sealant stick to everything. I then used the profile tool to achieve the final shape.
Next was to get a spray bottle, with 30% dishwashing fluid (balance water), and spray the Sika, and your finger, and wipe along the seal. Since your finger won't stick, the Sika surface will become silky smooth and dirt won't stick down the track.
Next remove the masking tape, and use the dishwashing solution to blend any edges that have a lip from the masking tape. Note: The Sika won't stick where the dishwashing fluid is.
Waited 3 days for curing. NO leaks!!! and $29 bucks! Hooray, now to book the next holiday down the coast!
