Hi all.

I have a problem with rust on my 1996 XM Estate, I've been posting on the other forum about it but maybe could get help here too.
I had a rusting cross member of my chassis right behind a jacking point that had been bent years ago, I did'nt try to straighten it out then as I knew that could weaken that part of the chassis, but had to to get to the rusty part so I staightened it as far as I could to expose the rust.
It was when I was checking the car ready for MOT when I found a little rust spot behind the jacking point which turned out to be a large rust spot which needed a large patch welded in. That got through the MOT but the examiners fingers went through a floor section behind my towbar. I removed the towbar and got through with an advisory.
My problem is what is rotten? The Estate rear floor is solid!! But under the rear at the end of the main chassis members is a box section running the full width of the rear, between that and the bumper is a 3inch gap and at the top of this is a floor, but what of? Is there a gap under the estate rear floor and another floor just on top of the chassis? If there is how do I get to it? If I remove the bumper and shock absorber material will I get into it or is there a plate across the rear to hold the bumper?
Any advice would be gratefully accepted.

Bob

Hi Bob,

Its very unusual to hear of someone complaining of rust on an XM mainly down to the fact that the shell is galvanised. Sorry to hear that your car appears to tbe tha exception. It sounds to me like its been used to tow a boat trailer and has been reversed into the sea a few times. the chlorine content will go for unprotected mild steel which may not be galvanised. It was probably only the monocoque which was galvanised and not the chassis.

I'm afraid I don't have time to take my own bumper off to have a look but I can have a look with you when I get back from holiday in a couple of weeks time if you wish. It would be prudent to find the problem now and offer protection to whats left rather than wait until it comes through the floor. A little prevention goes a long way as they say.

Cheers
noz

Hi Bob

Does the attached parts sketch help to clarify the layout?

Ken

Hi Ken.
The download comes up all kinda funny! Squiggles and a lot of icons! Can you send it as a PDF? Maybe I could open that.

Hi Noz.
I have owned it since new and the nearest I get it to the sea is at my caravan at Dunbar! And it's not the shell, it's perfect. I got a couple of rain-free minutes and opened up the tailgate, removed the plastic strip on top of the bumper and lifted the mat and the foam. The foam was wet for six inch's from the end but the steel floor is perfect. whatever is rusting is under that and on top of the monoquoc chassis and seems to have a gap under the floor of the estate rear.
I want to treat it with anti corrosive products from Bilt-Hamber and would like to have it all to hand before removing the bumper but only if the bumper allows access to this space!
Hope you have a good holiday Noz.

Bob

Hi Bob

Right click on the file attachment and select 'Save link as...' to your desktop
File will save as 'index.php'. Right click on this file, then select 'Open with...' and 'Microsoft Word'. A bit of a faff but should work.

Ken

Hi Ken.

Sorry to be a pain in the ****! I don't use MS Work, only Lotus for me so can't open the file.

Bob.

Hi Bob,

Right click the file on the screen and if you have Internet Destructor choose "Save as" or if you have Firefox choose "Save Link as...". In both cases a save as dialog box will open. Normally the filename would appear automatically and match the filename on the screen but the glitch in the forum software means that it appears as index.php. In the box where it says index.php change it to any filename you want. However, if the file you are downloading is a pdf then the filename must end with .pdf and so on. Once it has saved to your HD you can open it normally with the associated programme.

In the case of the above file it is a pdf so save the file as "ECU Models.pdf" for example.

Hope that helps.

cheers

noz

We'll get there in the end Bob!!

Try this file. It is a .jpg file.

Ken

Apologies Ken,

Its been a long day. It wasn't a PDF of course. I was on the wrong planet when I wrote that.

Sorry

noz

Hi Ken,

got it, thanks. The drawing shows two bolts #70 holding the bumper in place, behind them the floor and this side of them a plate across the width of the rear. My problem seems to be below the floor shown and behind the end plate!
Taking off the bumper won't allow me access to the problem area. I have written to Bilt-Hamber asking if I could just spray some of the Hydrate 80 or it's Dynax S50 into the space to stop the rust and then seal the rotten floor with steel plate or even fibre glass, it isn't an MOT fail area.

Noz,
I get these moments too! More often as I get older.

Bob

Hi Noz

Afraid I cannot agree with your assessment that rust is unusual in XM's.
The body shell treatment alters and retards the rust process but does not eliminate it.
As a result the rusting is often hidden and turns up in unexpected places.
Also when protective systems fail very agressive rusting can happen at the point of failure. I have scrapped two XM's because of severe rust. I accept that had each one been my only car I might well have repaired rather than turned into spares. Nearly half of my remaining XM's (all Mk 2's) have needed MOT weld repairs in the last few years. Cills and floor box section cross members all tend to rust from the inside outwards. Front subframes go under the rads and on the underside where the undertray was fitted. Estates have particular problems with the rear cross members, box sections and wing supports.
The worst of my current batch is an M reg 2.5 exclusive which was left with the underseal failed. Bodywork gives no visible signs of problems but underneath the weld repair plates are now in double figures.

John

Wow John,

That's some list of welding repairs. My comment was based on the 3no. 2.5TDs I have. Each one is sound on the rust front. Admittedly, in each case the strip that runs along the front crossmember just behind the bottom of the bumper is rusty but never has it been so bad that it needed welding. If there were going to be cars which rusted badly I would have thought they'd have been here in Scotland with all the salt they use on the roads in the winter. One of my XMs came from the Inverness area, one from the Bristol area and one from Bexhill on sea. So 2/3 of my fleet haven't spent all their time on Scottish roads.

Why should our collective experiences differ so greatly? Do you live near the sea or something? Can you think of any reasons why you've encountered so much rust? I have to say I was unaware of any rust problems with XMs.

noz

Hi Noz

I intend to run 2.5's as working cars hopefully for another 15 years or so.
As you may remember I have been collecting for some years now.
The blurb of a protected bodyshell lulls us into a false sense of security.
Because of my interest I was generally looking at any XM that I came across.
A good few years ago an accident damaged Mk1 XM being repaired by one of the XM specialists caught my eye while I was looking over his stock. One side was stripped out and the large amount of rust in the thin sections caught my eye. Put it down to being
a one off. Could not ask about it because I should not have seen it anyway.
Next wakeup call was about 5 years ago when one of my R reg estates failed the MOT on a holed outer cill. Small hole but critical area. I had missed it but the tester did not.
Since then I have been looking in ernest including sectioning the chassis of the two 2.5's that I have scrapped. Have kept subframes for refurbishing because that is such a problem to deal with on car.
Still been a bit surprised at the extent of the problems and the differences between cars. FSH, CCC money no object previous owners and detailed examination before purchase are all no real protection against the risk of hidden rust. More recently I have tended to buy towards the bottom of the market viewing the cars as mobile cheap servicable spares. Running the spares for a year or two tells you a lot about the condition of them before they go on the shelf.
Have taken a few rust photos somewhere so must sort them out one day.
Like strut heads I have tried to research the background causes of the rusting.
I think that chassis seams and spot welds provide gaps in the protective coating and aggressive pinhole corrosion can start off at these locations. Damage to chassis joints (eg lifting points) can be another rust initiator. Anything that retains moisture over these damaged areas (wet above floor foam, undertray, failed underseal etc)
feeds oxygenated moisture to speed the rusting.

Have a good holiday.

Regards

John

Hi all, especially Ken, Noz and John.

I got the car up on it's highest and went under it with my camera, I'm not too hot on getting photo's onto the forum so sorry in advance if they are not up to scratch.
First photo shows the rusted bit just behind the towbar fixing point.
Second shows the bolt holding up the spare wheel, the rust is behind that.
Third shows rust again right behind the towbar fixing point
Fourth is the tailgate with the carpet, mat and foam raised and plastic removed. Please excuse the dirt that appeared!

Ken. What is the part numbered three in the picture you sent as I think that is where the rust is, because the rust is too far behind the spare wheel securing bolt to be part of the bodywork. What do you think?

Bob.

Hi Bob,

That rust does look serious!

Item No 3 is called 'Bumper Absorber' and is in two halves, right and left. If it is anything like the front bumper absorbers it will be made of dense polystyrene foam or plastic.
I believe it's function is to support the bumper and absorb impacts to the bumper thus reducing the possibility of rear stuctural damage to the bodyshell.

The rusted transverse box member that you have pictured would appear to be located in front of the rear panel (the one with a row of holes in it) that the absorber and bumper are fixed to. I would think it sits almost directly under the two fixings marked No 70 on the sketch.

I will dig out and post the other Citroen parts sketch for the estate rear floor which should show the other sections which make up the structure.

Ken