XM 2.5 - Bad Egg Smell

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rg
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XM 2.5 - Bad Egg Smell

Post by rg »

Folks,
There is a smell of bad eggs at start up. Excuse my ignorance, but does the 2.5 have a cat? I've not needed to get that intimate with the underbody as yet. Thankfully.
I know what a leaking matrix smells like, and I am pretty sure that it's not this.
Anyone else experienced this?
rg
edd001
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Post by edd001 »

you have not put the year of your car but i susspect it has got a cat and that it is the cat that is causing the smell.
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AndersDK
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Post by AndersDK »

Battery acid spillage smells exactly like that too [:I]
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Post by rg »

Thanks,
It's a '97 ORGA 7175
So it has a cat?
I am surprised that the fumes come through so quickly - it the cat fairly close to (and below) the scuttle/bulkhead area?
rg
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Post by happychap »

had this on my b.x once , could not locate it anywhere , only happened on start up , turned out to be a manky screenwash resovoir behind bulkhead . took the whole thing off , washed and scrubbed it , no more problems .
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Post by rg »

Thanks
Yes, I have this on my other vehicle.
But the XM is different. I suspect a cat, but no-one can advise if it has one.
I think that I am putting off putting my boiler suit on and crawling underneath.
rg
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Post by RichardW »

It might have a cat, but as it's diesel it's unlikey to make a rotten egg smell - the cat only turns NOx back into nitrogen. I would start by looking at the battery - but didn't you buy a new one only a few weeks back?
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Post by rg »

Richard W,
Well spotted! (spookily so...)
Yes, the battery is new.
Coolant loss is very slight (100cl approx over 450 miles due to very slight occasional leaks from the large radiator - 2.5 has two)
So I wonder if something nasty is stuck in the scuttle area, or bits of leaves are going "off".
But, to me, it's a very distinct bad egg smell. Not like leaking coolant at all. The "elbow" of the matrix adjacent to the parking brake is bone dry. Maybe time to investigate the other end.
Thanks, all
rg
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Post by David W »

Hello RG,
My exhaust book shows all XM diesels without a cat. Richard is right too that a diesel cat doesn't smell in that way.
I have two guesses to add. Not a tomcat scent marking in the scuttle area? What about an overheating electrical connection, this can smell odd.
Good luck sniffing round!
David
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Post by rg »

Hello D.J.Woollard,
Funnily enough, the cats (feline) seem to be drawn to the XM. We have had a cat lover move in across the road six months ago, and there seems to be a floating team of around six who live there.
These days I like cats even less...
Maybe these things could be trained to change glowplugs with their teeth, rather than consume expensive cat food, and recycle it into toxic excrement on neighbours gardens. And ferry fleas from local wildlife into the owners duvets.
No, but it does smell chemical rather than organic.
I have used a site which decodes the VIN and gives a spec. of the car as manufactured, and that says it -does- have a cat.
Take care, and thanks once again.
rg
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Post by alan s »

I know I shouldn't but hell I can't resist this!!
Sticker on the rear window of a car I saw recently
<b>"Neighbours cats; make great HATS!!</b>
I love it.
Alan S [:D]
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noz
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Post by noz »

rg,
The presence or otherwise of the CAT is a moot point. The purpose of the cat is to convert oxides of nitrogen and sulphur to harmless states where they can't add to the acid rain problem. The rotten-eggs smell is consistent with Hydrogen Sulphide. Modern fuels are advertised by their 'Low Sulphur Content' which concerns many car owners because the Sulphur has lubricating qualities which are lost if it's removed. The debate on this issue continues. If it didn't have a CAT and the fuel contained Sulphur then it would appear at the end of the exhaust. If it had a CAT and it wasn't working, the smell would still appear at the end of the exhaust. If the smell is no worse than a car with no CAT using the same fuel then it has nothing to do with the CAT.
The other location of Sulphur in the car, apart form the tyres, is in the battery. The battery contains a solution of Suphuric Acid. A rotten-egg smell (H2S) will emanate from the battery if it's being overcharged. The overcharging changes the Sulphur molecule from the sulphate form to the sulphide form. Apart form the smell it's relatively easy to diagnose since the battery will be warm/hot to the touch depending on how severe the overcharging. I have seen a battery literally boiling like a kettle when being overcharged.
Hope this helps
Cheers
noz
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Post by rg »

Noz,
Based on the VIN number, it does have a cat. i will take a look at the battery. I just get a blast of it on start-up, rather than after the engine has been running, so overcharging may not be the issue.
Thanks for the advice, though..
rg
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