Rusty sills on ZX

[the_weaver]

Hi folks

I think I'm going to get some welding done on my ZX soon. I've got rust holes in the sills, at the front and at the back, on both sides. I'm planning to get a garage to weld four patches on. Does this sound like a reasonable plan, or would complete sills be better/cheaper? Are sills available as repair panels?

How structural are the sills on the ZX? The outer sill seems quite thin. Is the inner sill the main structural part? There are two big box sections running down the floor on the ZX. Do they provide the main strength of the car?

There's some surface rust on the inner sill (visible though the rust hole in the outer sill), which can be wire brushed off before the welding, but how do I protect the inner sill from further rusting? There's no point in painting it because the welding will burn the paint off. Once the outer sill is welded I won't be able to get to the inner sill to paint it.

If I decide to get the sills renewed completely, are there any precautions that need to be taken to avoid the chassis bending while the sills are cut away? Should the job be done one sill at a time, to minimize the stress on the car body? Is there any need to fit a steel brace across the open doorway while the sill is being worked on? I've seen these methods used on other cars in the past, but I don't know if it's required for the ZX.

Paul

[citronut]

really depends on how far the rust/tin worm has attacked the sills, can you post picy's,

even if you were to cut the outer sills away completely the shell would not distort enough to cause any problems

i haven't heard of complete sills being available but then i haven't been looking

[the_weaver]

Thanks for the reply, Malcolm.

I'll try to get some pictures posted tomorrow.

I think some of the rust is in the area of the jacking point, where the Citroen supplied jack fits into it's locator, (to stop the jack slipping off the sill). I suppose there's not much hope of saving or replacing the locator. I'll have to use a bottle jack somwhere else.

Paul

[Old-Guy]

There's some surface rust on the inner sill (visible though the rust hole in the outer sill), which can be wire brushed off before the welding, but how do I protect the inner sill from further rusting? There's no point in painting it because the welding will burn the paint off. Once the outer sill is welded I won't be able to get to the inner sill to paint it.
Paul

Inject Waxoyl into the repaired and painted sill through a hole somewhere inconspicuous that can be blanked with a grommet.

[citronut]

the jacking point is a substantial chunk of metal so id be surprised if it could not be repaired around that and save it,

the usual point ZX's go is the outrigger were ignorant tyre fitters and mechanics use this as a jacking point,

[the_weaver]

Thanks for the tip about Waxoyl, Old-Guy.


Here are some pictures of the rusty sills. I've taken a normal view, and then a closeup, for each of the four corners of the car.


Offside front:-


Offside front closeup:-




Offside rear:-


Offside rear closup:-





Nearside front:-


Nearside front closup:-




Nearside rear:-


Nearside rear closeup:-

[handyman]

Oh dear, those sills do look bad. In the past, I had broken a couple of ZXs with a similar amount of rot, at the inner sills had gone and started to eat into the floorpan. The section of sill you show near the front footwell and jacking point, it might be as well to lift the carpet, cut out the sound deadening material and see what state the floorpan is in around that area, especially along the outrigger to the inner chassis rail.

I've not come across any genuine sills, although they were listed as a replacement part, now NFP, as I was looking for a new inner wing assembly. The sills on my ZX were perfect and might be salvageable from the fire damaged wreck. Let me know if you're interested.

There were pattern sills available from one or two suppliers, but I do seem to remember they were an interesting fit as they were a 'capping' sill.

If you have this amount of rot on the sills, it might be as well to check the chassis rails, inside the front turrets and inner wings for corrosion as these might also be areas that need attention at some point in the future.

Handyman

[bxzx16v]

Your sills look petty nasty on your Zx . As mentioned clumsy mechanics/tyre fitters don't help the situation . I've got my jacking points to clean up but it's mainly surface rust at the moment , I just want to stop it taking hold , I have got a product from bilt hamber called deox gel which chemically removes the rust . And I've got some of their cavity wax too to spray into the sills . I'll get some pics posted up on the product at work , at £10 for a massive 1kg pot it's not bad value either , apply leave for desired time then rinse , leaving bare clean steel .

Mark

[citronut]

I have got a product from bilt hamber called deox gel which chemically removes the rust . And I've got some of their cavity wax too to spray into the sills . I'll get some pics posted up on the product at work , at £10 for a massive 1kg pot it's not bad value either , apply leave for desired time then rinse , leaving bare clean steel .

Mark

i think it is a bit to late to use that product on the_weaver ZX

if you send me the last 8 digits of your chassis/VIN No. i will get you the OE part No.'s for the door sill sections from service citroen

even thoufgh they are all coming up as NFP (no longer available ) you could do a googly search, as someone somewhere might have some stashed away

[the_weaver]

Malcolm

I've sent you the last 8 digits of the chassis number by Private Message.

Paul

[the_weaver]

Handyman

I've had quite a bit of welding done on the inner wings. I've also had some welding done on the floor, at the front. Probably one side was welded due to the outrigger problem. The other side was welded due to rust being close to where some bit of chassis was bolted on. I can't remember the exact details. The floor is not too bad really. There doesn't seem to be much rust coming through the Citroen underseal anyway.


bxzx16v

I use Loctite Rust Remedy. It chemically changes the rust into a stable coat. The rust turns blue. The paint on the metal stays white or grey. It actually works, unlike a lot of other products.


Paul

[handyman]

Hi Paul. looks like you're already committed to chasing the tinworm on your car. As you probably know, it can be an expensive pastime, both in materials and time. Sounds like you have had the double skinning in the floorpan around the rear part of the front subframe repaired. Not an easy repair.

You will probably find that the compound you are using as an inhibitor changes the iron content of the steel from ferrous oxide into ferric oxide, which is less anhydrous and therefore less prone to rust. It usually uses phosphoric acid to achieve this and smells a bit like vinegar! Downside is that it makes the steel difficult to weld afterwards, especially with electric arc, MIG or TIG, as it forms a layer of inert and electrically insulated salts in the steel platelets. Lots of splatter on the welds.

I used to swear by Jenolite as a rust inhibiting compound for steel. Tasted good on chips as well!

Interestingly, the pre-1992 cars were less prone to the attack of the tinworm. Might have been something to do with the galvanizing process the bodies went through.

A few years back, I meet the engineer who designed the system for Citroen. He worked for a company in Crawley that built the plant and sent it out to the various satellite factories for PSA. Last time I saw him he was showing the initial signs of dementia, a real shame.

Handyman

[citronut]

here are the part No,'s for the sills to fit your car

95 658 495
NFP
SIDE PANEL
LEFT
INF


95 658 491
NFP
RIGHT
INF

and when they were available they cost £164.98 each

[the_weaver]

Malcolm

Thanks for the info.

Paul

[the_weaver]

Handyman

I was going to use Loctite Rust Remedy on the rust on the inner sill, before taking it for welding. However, if ferric oxide is more difficult to weld, then maybe I shouldn't use it.

Paul