B234F smelly exhaust - emissions?

[rogerthechorister]

The mecco who is doing a range of things to my 740GLT (B234F) is worried she will fail MoT on emissions. She has always sailed through emissions in the past, but she has been standing for some months while he tinkers with welding and other bits. He now says that although she starts cleanly, and the exhaust gas is invisible once warm, she smells like a diesel once hot - rotten eggs smell. Normally cold cats smell like that but not hot ones.

He also points out that there is a water drip from the exhaust at cold start but I think that that is normal.

I'd have suggested an Italian tuneup if she had an MoT - but it went out in early November while he was fiddling.

I am open to suggestions - the cat on these is cheap so maybe start with that?

[827Roverman]

Originally Posted by rogerthechorister

The mecco who is doing a range of things to my 740GLT (B234F) is worried she will fail MoT on emissions. She has always sailed through emissions in the past, but she has been standing for some months while he tinkers with welding and other bits. He now says that although she starts cleanly, and the exhaust gas is invisible once warm, she smells like a diesel once hot - rotten eggs smell. Normally cold cats smell like that but not hot ones.

He also points out that there is a water drip from the exhaust at cold start but I think that that is normal.

I'd have suggested an Italian tuneup if she had an MoT - but it went out in early November while he was fiddling.

I am open to suggestions - the cat on these is cheap so maybe start with that?

Put a tube of LIQUY MOLY in a half to full tank, then give it your italian tune up,

[rogerthechorister]

I have some similar stuff called cataclean - but I cannot legally do an Italian tuneup without an MoT!

[griston64]

Can your mechanic do it with his trade plates on ??

[rogerthechorister]

Alas none of the meccos I use have trade plates! Maybe I could find and engage one for just that purpose!

[griston64]

Originally Posted by rogerthechorister

Alas none of the meccos I use have trade plates! Maybe I could find and engage one for just that purpose!

Or you could just say you were driving to the MOT station ?

[Chooch84]

Methanol? Should drop your AFR a little, and it's safe on the cat. Obviously don't drink it due to the whole medical issues. How old is the petrol in the tank?

My driving instructor used to say that an eggy smell used to come off the cat in his Mk1 Focus, it was clearly him letting rip.

[Laird Scooby]

Originally Posted by rogerthechorister

The mecco who is doing a range of things to my 740GLT (B234F) is worried she will fail MoT on emissions. She has always sailed through emissions in the past, but she has been standing for some months while he tinkers with welding and other bits. He now says that although she starts cleanly, and the exhaust gas is invisible once warm, she smells like a diesel once hot - rotten eggs smell. Normally cold cats smell like that but not hot ones.

He also points out that there is a water drip from the exhaust at cold start but I think that that is normal.

I'd have suggested an Italian tuneup if she had an MoT - but it went out in early November while he was fiddling.

I am open to suggestions - the cat on these is cheap so maybe start with that?

Cats produce Hydrogen Sulphide (H2S) when they are up to temperature and working correctly - this is the "rotten egg" smell and is perfectly normal. When they stop producing this pong, they're in need of replacement.

Diesels are even more acrid and horrible IMHO and i much prefer the smell of cats although not fond of that either!

The water drip from the tailpipe is also absolutely normal, unleaded fuel not only has a higher water content than the old leaded fuel but with the addition of ethanol, this increases the water content. Methylated spirits (meths) added to the tank in a ratio of 1 part meths to 10 parts petrol (2L Meths to 4 gallons/18L of petrol or 1/4 tank roughly) will "mix" with the water (condensation) in the tank so it burns off with the petrol.

When it's hot this water appears (or doesn't!) as steam, usually invisible.

Also because it's been laid up a while, there will be condensation and probably a few spiders in the exhaust, i wonder if spiders smell like rotten eggs during cremation?

Seriously though, it doesn't sound as if you have anything to worry about, i always know when i've given my Rover the beans as i can smell rotten eggs - thankfully no cat on the 760 and soon enough won't be on the Rover either!

[360beast]

Completely agree with Dave.

Is the guy doing the welding a mechanic? Because he should know that cats smell eggy when working.

[rogerthechorister]

I always thought that cats smelt of H2S when cold, not hot. Yes he is also a mecco, and yes I could book an MoT and go the pretty way... And yes I know the theory that combustion of hydrocarbon in oxygen produces water and CO and/or C02 so I was not overbothered about the water.

Apparently people have been asking him is she was a diesel, she smelt that bad...

But thank you all for your views.