MK1 sill rust prevention and causes

[08SWB-connectOwner]

Hello.

I will be replacing the sills on my 08 SWB, to both repair and check for rust.
The other sill was already 'repaired' by the previous owner, less then a year ago.
I checked with an endoscope, and there's already plenty of moisture in there!

As I understand it, the rusting is caused by poor design, which lets moisture, namely condensation into the sills.
Since I'm making these repairs, I thought I might as well do what I can to prevent, or at least mitigate rust in the future.

Are there any specific modifications that could help to achieve this, beyond the usual cavity waxin etc?

Couldn't find a dedicated topic for this, or clear directions etc.
So I thought might as well gather this information for everyone else to find as well

Thanks!

[metalworker0]

All the sill section panels are made of 22 gauge steel , which is a very thin - 0.7mm that does not help.
Instead of making inner and outer sills out of much thicker metal ..Ford made a sandwich of inner, muddle and outer ..all out of this 0.7mm metal.
They added rust traps .and place for the water to get in, there are drains , but There are also a row of holes running along the entire sill...these are not drainage holes ..as they let water in .
see how this replica sill manufacturer has replicated the mistakes . see the row of holes.
https://i.ebayimg.com/images/g/xfkAAOSw ... s-l960.jpg


Behind each front wheel just where the wheel arch liner stops ..there is another hole to let water in strait off the wheel.

Construction details: last picture - the red region is where it rots the most... as you can see lots hidden boxes and what nots, that you cant see when you attempt to waxoyl it .

These sections have to be noted when you have it apart ..and during sill repair you have to make access possible by drilling holes and closing them with grommets, ready in place for the cavity wax.

any water that gets into the outer sill has to go through the slots in the second picture and drain out through the the swages in the inner sill, in the first picture.

[metalworker0]

Part 2 . Because of capillary action some water that is in the bottom of the sills stays in the the three panels pinch zone that are spot welded together, (the bit hanging down in the last picture) , the water sits in this sandwich for long periods of time , the British climate is very humid ..condensation in the panels happens often ,, so the sandwich is always being fed...results in swelling ..lots of layers of porous rust , that accelerates the process.

How to make your repairs last a bit longer

1.Use weld through primer

2. Pour in paint ..see pics below, red arrows are blue tack, Once all the panels are in place and welded up lay down some DPM sheets.....block all the drainage holes up with ..putty ..blue tack ..or what ever you can get your hands on , then fill the sills with about a pint of paint ...primer , house hold gloss ..what ever you can get your hands on - if you can get hold of red lead ..last made in the 70's ..this will be best. leave for half hour or so ..so that the paint penetrates the sandwich ,,, take the putty off and let it drain.

3. Waxoyl,
Note: waxoyle when used even warm will solidify when it hits a cold steel surface ..so to give it a chance to penetrate, follow below.
You want the waxoyle to penetrate every nuck, cranny and seam ..to do this the waxoyle has to be warm or even hot, so only do it in the high summer ..on the hottest day, if using air fed sprayer.
The shultz guns are garbage for this task and you should buy the Sealey one ...run the airline through a 5 gallon drum of boiling water ...or make a mini bore copper pipe up and immerse in drum. also heat up the waxoyle in bucket of boiling water.

4. The hidden box sections are important , these need waxoyle. if you don't do them then you may as well not do it at all .will be a waist of money.

all the best.mark

[08SWB-connectOwner]

Awesome reply!
Thank you!

Could I pour the wax in the same way as the paint (in step 2), and then use a heat gun to heat up the sill a bit, so that the wax stays warm as it spreads more like a fluid?
I understand this will require alot more wax, but the Sealey wax injector seems to be quite expensive. It'll be cheaper to buy litres of wax.
Maybe I could use the cheaper gun first, to get the wax all over the insides, and then pour in the wax?

[metalworker0]

if you pour wax in, i suggest you mix it with machine oil / hydraulic oil ..as it will set and block the drainage holes up "as is " even when hot. 50/50 mix will get it to penetrate ..then leave a couple of months and then do the normal spray job.

The sealey gun is about £120 with a gallon of waxoyl
The waxoyl gun, the hand pump - their own make, isn't that bad .and less likley to cool the wax down like the air version

Don't forget , there are other products like lanogaurd or Dinitrol

my thread on putting the sills on is here .

viewtopic.php?f=54&t=209329&start=30

all the best.mark

[Altransit]

my thread on putting the sills on is here .

viewtopic.php?f=54&t=209329&start=30

I've made that topic a stickey, so it should be easier to find.

[metalworker0]

IMPORTANT - when repairing inner sill ...note the depression in the inner sill, its there to facilitate getting the spring hanger bolt out.

if you cant replicate this ...suggest pulling bolt out and turning the other way around ..or you'll never get it out in the future!


all the best.mark