9 replies to this topic

[kada1980]

Whilst stripping and repairing the sills on my mini i noticed a lot of rust debris inside the sills even though the sills were fine on the outside. They must be getting water in from somewhere even though they appear sealed. I also had to repair a corner section of the doorstep panel the bit that goes all the way up to the roof via the windscreen, it appears that this is open to the sills so am i right in thinking that all the condensation inside the car will build up and hit the roof and run down those panels into the sills, which is why they are always falling apart? Has anyone consired filling the sills with expanding foam, it would stop water and moisture collecting and at the least would prevent rust from reappearing as frequently as it does.

What do you think? Has this been discussed before?

Cheers

Karl

[nomininolife]

I wouldnt fancy welding around that stuff, Im sure paint and waxoyl would suffice

[kada1980]

Not weld around it put it in once the sill is in place, through some small holes on the inside of the car. The rust still comes through paint and waxoil from the inside out.

[nomininolife]

When you come to weld the car again you run the risk of a fire ball

[kada1980]

When you come to weld the car again you run the risk of a fire ball

My point exactly prevention is better than cure :wink:

[Woody]

Are you sure the expanding foam would not act as a sponge and just stay soaked speeding up the rust ?

[kada1980]

I've been doing a bit of research and most of the expanding foams are made from polymeres which are insoluble and none porus, yes the coshh assements state that they are flammable but hopefully if it was to work then the panel wouldn't need repairing and if it did need to be replaced it would could be completely replaced and the foam removed. The basic principles of corrosion prevention is to isolate the metal from atmosphere and water. What i'm trying to achieve is to stop the water collecting in the sills, most cavity walls are filled with the stuff and you rarley notice damp coming through the walls because of it.

[chairchild]

but any water that gets in (you've still got the drainage hole in the bottom remember, that let out condensation) will be trapped against the metal because the foam wont LET it go anywhere

One option I'm tempted to do, after hearing of it - is to de-rust the whole area after taking the sills off, spray them with zinc primer, and weld it all up (handy stuff zinc primer - you can weld through it!) and then drill 2 large holes into the inner sill. Spray the insides with waxoyl, then stuff the sills full of oilly rags - just to be sure. Then either fit a grommet into the holes, or cover with some gaffa-tape :wink:

a bit overkill - but hey!

[Guess-Works.com]

I was condsidering the option of Foam filling the sills, not so much to keep the elements out, but to act as a sound deadener... I know theye are completely rust free as I've put them on, and will be shutzed internally first anyway...

As you are working on the principle that there wont be any further welding necessary for a while, I'm still tempted to do it..

and on principle, if I did have to weld on the sills, they would come off anyway ( don't like patching outer sills ) so would give the opportunity to clean foam out anyway

[kada1980]

Guessworks my plan exactly, i know that theres still a little rust inside the sills so i'm temted to fill them up with foam, from inside and see how long it takes the rust to come through, if you don't here from me for a few years you know its worked :grin:

When it does come through again the whole sill will be getting replaced so it will need removing completly and the foam isn't that hard to clean out it just breaks off in chunks.