Rust hole in side sill on door step

[peter54smith]

Hi all I have a rather large hole developed on my passenger door step at the top of the sill, and am wondering how to repair it. I was thinking of spraying in a mist of rust converter letting it dry and then pumping it full of waterproof gorilla expading foam, as this will expand within the sill from back to the front making a water proof and airtight seal stopping further corrosion. Also the sills on the mk2 are not strengthened locations so there will be no problem with loss of body strength what do you think.

[jimako]

Hi all I have a rather large hole developed on my passenger door step at the top of the sill, and am wondering how to repair it. I was thinking of spraying in a mist of rust converter letting it dry and then pumping it full of waterproof gorilla expading foam, as this will expand within the sill from back to the front making a water proof and airtight seal stopping further corrosion. Also the sills on the mk2 are not strengthened locations so there will be no problem with loss of body strength what do you think.

Put up a picture of your rusty hole

[erad]

Depending on the size of the hole, and its visual appearance, I would tend to kill the rust with converter, and then simply paint over it. Filling the sill with foam may impede drainage and cause more corrosion problems further down the track. The sill panels are not structural with this model so it should not be a problem.

[NFT5]

Almost always, rust starts on the inside and works out. What you need to do is find how the moisture is getting in there and address that first. The foam idea, while novel, may just exacerbate the problem or move it somewhere else that may not be quite as easy to fix.

In terms of fixing the rust hole(s) there is only one way and that's to cut out the affected area and patch the panel. Rust convertors are, largely, a waste of time and money - the rust just comes back unless you actually fix the cause.

Once repaired a sealing wax is usually the best preventative for the inside while the outside should be sealed with an automotive two pack epoxy, before normal finish coats.

Although not structural in the same way as a monocoque body, your sills still provide an important part of the side strength and impact absorption. They really need to be fixed properly.

[peter54smith]

Crusty rusty paji

Thanks for the replies chaps I shall post a picture as soon as I can but I'm thinking of cutting out and patching with a small panel using a mig my thoughts on using gorilla water proof expanding foam was that it would fill up the section completely stopping air and water hence stopping further rust but drainage needs to be considered as you have stated I hate crusty rusty crud still at 23 years old paji one has got to expect a bit here and there I suppose. Regards