C3 Picasso outer sill internal access.

[Murphyv310]

Hi.
I wish to inject cavity wax into the cavity on the outer sills to protect its internal surface.
Where can I access this or do I need to drill holes which I'm not keen on.
Thanks in advance.

[white exec]

Take a look at the rear end of the sill - where it becomes the rear wheel arch.
Good few of our cars have a grommet there, for (factory) still treatment.

Some Citroens have a double-cavity sill arrangement, with an internal vertical sheet dividing the sill into two - done for strength, using thinner metal.

[Murphyv310]

Hi
Thanks for the info. Asx far as I can make out the C3 Picasso has a double cavity Sill. I'll get a look behind the rear arch liner and see if I can locate a plug or blanking grommet.

[GiveMeABreak]

These sill components seem separate without a cavity as such:

Reference	Designation	Thickness (mm)	Nature/classification
(2)	Inner sill	1,95	High strength
(3)	Front pillar strengthener	1,76	High strength
(4)	Inner sill strengthener	1,17	THLE
(5)	Stiffener : Lower centre pillar	1,17	High strength

[Murphyv310]

Hi Marc.
Thanks for the diagram, very helpful. I've some bubbling about three inches behind the centre pillar, it's on both sides. I have carefully looked to see why. Removing the trim from the centre pillar and those covering the sills above the carpet reveals a complex inner sill and a strengthening piece, you cannot see the outer sill. I don't see how water or moisture gets to the area. I've removed all the paint and sealer from the outer sill and cleaned off any small amounts of rust and treated it from the outside. At this point I'm not too sure if it was water under the sealer or from internally. I suspect from inside as it's in identical positions on both sides. I want to spray Lanoguard inside to see if it halts the issue, if not its a job for a bodyshop and a little welding, rather do it before it spreads.

[white exec]

#4 in Marc's diagram seems to partially divide the sill cavity into two, albeit not for the full length (which is done on XM, for example).
If there's no rear bung for accessing the outer part of the sill (ie immediately behind the visible outer panel), you might be able to drill a hole on the top side (door shut area), maybe under a tread-plate, if you have such things. Alternatively, a small hole and a grommet on the top side might be better than not waxing the sill at all. Sills do tend to rust from inside outwards.

[Murphyv310]

Hi.
Well lo and behold after drilling a hole right above the door shut gap I've discovered the reason for the corrosion. There is a foam piece right at the point of the issue inside the sill.
I managed to budge it with very stiff wire so it's now lying in the sill cavity. I've sprayed a lot of Lanoguard Moto spray into the cavity and will see what transpires
If it comes back I'll get the section cut out and remove the foam and get a plate welded in from behind and then get it dressed on the outside for an invisible repair.

I suspect that this part of the sill will rust on many C3 picasso's given time and the area they are living in.

[white exec]

That's a disgrace — foam placed in the sills!
It will have been put there to stop resonances.
Last time encountered that was on an Austin-Morris 1300, where the rear section of the sill cavity was stuffed with bathroom-quality sponge foam, which continued up and over the rear wheel arch. Terrific! It was hiked out in one long piece, discarded, and replaced with a thorough internal coating of waxoyl.
Buggers.

Your avatar is well chosen.

[Murphyv310]

Hi.
Well something strange has occurred. I was able to move the foam on one side with a wire coat Hanger but the other side it didn't budge. I gave both sides a copious spray of Lanoguard. Today I was going to try and move the foam and its disappeared!!! There is seepage of a black gooey substance from the front edge of the sill. I hope the reaction of the lanoguard to the foam isn't corrosive. We will see.
I will spray more in today and observe what transpires.