Save our Sills!

[MTXM]

After a couple of my cars recently needed welding on the sills I decided to have a go at something I ought to have done before now that was to pump waxoil into the cavities! The Germany 24v sills look near perfect with no damage to jacking points or serious corrosion visible and there has also been no welding to my knowledge, which was a further incentive for the work. I recently invested in a pump/spray device and a 5ltr tin of the clear waxoil and had a crack at the task earlier today.

Earlier I had confirmed that good access can be obtained after removing the plastic threshold strips and screw plugs and the pump came with a hose of just the right size. In general the work went well, although I should probably have diluted the waxoil further as the pipe regularly blocked and several buckets of hot water were required to keep things flowing! I also sprayed inside the lower doors through the drain slots that worked quite well but unfortunately in the case of one front door the damage has been done with quite severe rust. The drain holes in both the sills and doors were checked and cleared before and after the operation.

The Poland car sills were treated when major welding was done and I now just have to do the doors on that car and the other cars and preferably during nice warm dry weather!

Regards,

Matthew T.

[Dieselman]

If one has access to a compressor, the access bung at the rear of the sill allows a larger pipe to be fed in the complete length of the sill. I recenty did the mandarin car and need to do the cobalt one.

[MTXM]

That is correct Will there is access from the rear bung, but I thought filling the whole sill might be slight overkill! The access from above along the whole length also gives greater certainly of even coverage and I also quite like the control of a low pressure spray. From my experience it is mainly the bottom section that fails where the water collects! Regards, Matthew T.

[Dieselman]

Hi Matthew. I didn't mean fill the sill cavity, just use the rear bung for access using a long tube.

I have an 8mm ID tube and a spray head, which sprays a fine layer of rustproofing wax-oil onto the inside of the cavity.

[White Exec]

That's how I last did our sill cavities - through the large bung at the rear end. Used a Sealey waxing gun, on a compressor, and slowly withdrew pipe as the spray went in. Found 4CR brand cavity wax rather good.

[russ92xmsed]

Don't forget the sills are in two sections. The outer making up the biggest cavity. The inner is far more tricky to get too. I found a useful hole in the footwells Wherei pumped oil into, and also removing the front puddle light switch in the door frame, you can poke a tube through it and you will find there is a handy hole in the metal pressing which you can then get to the inner cavity. Trouble is, it's harder to reach the further you go back. But as most of the rust issues are at the front, typically, hopefully it will help. I have a peice of floor and front sill section cut out of a mk2 car, and it's quite interesting to see the front cavities and how the panels are all joined.

Matthew with your large sill sections from Dave's car, can you see the different cavities and how to access the rear inner parts?

[White Exec]

Russ, you've reminded me of all those half-hidden holes where wax/oil can be injected. I also unbolted the seat-belt reel, and used that central opening. Also lifted sill protectors, and went in through there. Hopefully, swatted all the surfaces - it certainly took a bit of time to get to everything.

[russ92xmsed]

I used the door catches too by removing a screw. At least it can track down to the sills and coat everything on its way.
You are right Chris, you can spend ages tearing the car apart just to find that access point.

I must look for this bung though and try the cavity wax method too.

[White Exec]

Bung/stopper is on the rear vertical face of the sill/box-section - bottom front end of the wheelarch. Just pull the plastic liner aside.

[xantia_v6]

At the front, where the A pillar meets the sill and goes down to the jacking point, there is a third skin and cavity, which appears to catch water which has run down the inside of the A pillar. Sorry I dont have a picture, but I suspect that this is a starting point for rusted out jacking points, because there is no exit for water trapped there.