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E51 The E51 Catalytic Converter Problem

RiverBeast said:
Thanks, I think I will get the rears done. have you had any problems with MOT? I’ve read here that if they notice any tampering it’s automatic MOT fail.
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I have owned Boris for 6 years and never had any problems with the MOT. In fact it was MOT’d yesterday and passed. It could have failed on wishbone rubbers but they either didn’t notice or didn’t care. I went for the option of replacing the cats with straight through sections, so the originals are still intact if I need them.
Some people take the cats off, cut the top open, smash out the contents, weld them up and put them back on again. Either way I think you would be very unlucky to find an MOT place that knows enough about these cars to realise that they are missing, and even if they do, consider it to be something they would fail the MOT on.
 
Thanks Pete, I feel a bit more confident about it now. I think l’ll do the same and get straight-through back halves. I’m assuming that’s a simple job any exhaust company can do, whereas decoring might need a specialist.
 
I bought the parts from eBay and had them fitted locally. In retrospect I could have fitted them myself. I was surprised to find out later that a local tyre/exhaust company could have also supplied and fitted these parts.
 
Frogeyepete said:
I bought the parts from eBay and had them fitted locally. In retrospect I could have fitted them myself. I was surprised to find out later that a local tyre/exhaust company could have also supplied and fitted these parts.
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like these?: https://www.ebay.co.uk/itm/255705216648?hash=item3b8937f688:g:9nEAAOSwOd5jEMdp&amdata=enc:AQAIAAAA8JdidrybqPpkRNT2u5yGTDZztlEBGpR4ACd6n2Srx7U6R1fMNd+wzVr83ToGywFCDhbo+5lFpQ2XW++A6F72HA1ZILEkwnUmKINmntECmZgd5GDtWz6LfPOnHMDSGMMM9orqim8+92MsOJ2s7AIDaX3CfstmOci/pPPquBdx2uUfA8QpK6Q2Q4aSwUK1jjNFI6rQRgnn8AmKrx3HgIUcqeF3i9AHv3S/PqJbkn/PjZGCXcV7GkcIwaTZSiu/Rbnu5guvDOmdQAC2gY7bjZnXGIYR3Vdf793l7/bML0u5cLjlL58jVVMhbR9m7UmuOLvEzA==|tkp:BFBM7K3xwYpj

or these:

https://www.ebay.co.uk/itm/125377917488?hash=item1d311b3230:g:sXMAAOSw9URlAvUP&amdata=enc:AQAIAAAA8HdfGNcZqKhO1k8TBkmFJympFCf5JZwvnhWQPRuHemd/qzGtVwxqgGJByA1/mOt1JUu6lkSlYuOtiKU72O/fTmyjh8PhfT9iloxmP9hJqNetLElPpTVYa1TK/eDmT2Npfi86xTRRb1daA73KaaFbysDIKjBszErKQyqnpRMBDH9rYn4ixAz06zXkVx+P2keQ7bb5MI0w8eBKyCjaUy1j1K8XBWlZ+dl+EWgVpHin/r2vF3dTB1GRiVSE9FNL8O7F9I9JbQdnpWz/gkX4PEIT7pzD7ZKK0oYTx1FeFqFF4FLl3Z2DFk5Kb6VE7Mx5DMqagQ==|tkp:Bk9SR-yt8cGKYw
 
I can also buy second hand decored pipes. I’m thinking new straights is better than seconds hand decored cats though?
www.ebay.co.uk

Nissan Elgrand E51 Decorded Rear Cats | eBay

<p dir="ltr" style="margin-top:0; margin-bottom:0;">Nissan Elgrand E51 Decorded Rear Cats.</p> <p dir="ltr" style="margin-top:0; margin-bottom:0;">These are decorded cats same like decat. Straight fit and, generally good condition m one side heat sheet missing but won't make any problem </p>
www.ebay.co.uk
 
I hope that someone with more technical knowledge on this subject can step in and advise you. Assuming your car is pre-2010 it seems that both the eBay options should fit. If it was me I would probably go for the stainless option. Partly because the back box I have is stainless and partly because stainless will last longer. Having said that I would have thought that the cheaper option will last at least 5 to 10 years anyway; by which time you may have moved on.

Being a bit of a tight arse, I would be very tempted by the original parts with catalyst removed. 1) Because they are substantially cheaper and 2) Because they will almost certainly fit.

If you go for the ones with the catalyst removed I would ask the seller what year of car they are from and how the catalyst has been removed.

I think you pays your money and takes your choice.

Check the returns policy on anything you buy from eBay.

As I said I hope that someone else can give you a more definitive answer.
 
Thanks for your thoughts. I’ve ordered the new set for £255, the black one, just because it’s all new. Now I feel confident taking it to any exhaust mechanic and asking them to fit it. I’d do it myself, looks easy enough, but I haven’t got a ramp so will just book it in locally. Thanks all, you may have helped save an engine in the future
 
Well, long story short, trying to make set of custom flanges and bought an offside exhaust manifold from 2.5 VQ just to get the sizing from….I’ve seen some exhaust manifolds but that got to be first one covered in this whiteish dust, just curious if that could be that ceramic dust. Obviously could be anything but would be strange coincidence if it was indeed sign of breaking down front cat

73dd31b6b109db3fe033f846d40ca43c8e988c87.jpg
 
If it was like this whilst running I’d be saying more like running lean although those deposits are very white
 
I thought that too but somehow it’s only towards the cat, halfway through I’ve seen plenty of diesel and petrol ones and never seen anything like it, soot and sometimes odd burned matter but that’s not the usual colour of burning lean.
 
Sometimes if an engine is run on LPG there can be white-ish deposits which are not a problem... It's because when an engine is run on petrol or diesel quite a lot of soot is produced which is black, while running on LPG there is nowhere near as much soot. Normally if an engine is run on petrol a spark plug might pick up the usual grey-ish deposits, grey because grey is somewhere between black and white (even when an engine is run on petrol or diesel there are some white deposits, just that you don't usually see them because the overall general colour is more black).. If we removed the black colouring the grey would look white. Also Dave mentioned condensation... When we burn any hydrocarbon fuel (petrol, diesel, LPG) some water vapour is produced because when we burn hydrogen with oxygen from the air it produces H2O water, so if we think condensation is likely to leave white deposits we should expect more white deposits when running on LPG because LPG has a greater percentage of hydrogen in it's make up than other fuels (which have a greater percentage of carbon).

But, yeah, obviously if you were not decoring cats you'd want to make sure the white deposits were not cat dust before re-installing the exhaust section. I'm just explaining the potential for some white deposits if an engine has been running on LPG, I'm not saying those white deposits are not cat dust.
 
Highway Dave said:
Do you know the history of the motor this came off, I.e did the cats fail, was it poorly etc
I think some octane boosters will cause this too—-remember the e10-e5 debate lol
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I’ve used octane booster on e5/98 and witnessed one thing, the mpg is absolutely horrible, which is weird.

Edit. I mean the mpg is pretty horrible anyway but after octane booster and driving steady above 60mph I can see the fuel gauge going down with my bare eyes, it’s that bloody fast.
 
WeldHog said:
I’ve used octane booster on e5/98 and witnessed one thing, the mpg is absolutely horrible, which is weird.
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Yeah there’s too many on the market that do nothing good unfortunately.
You may never know what caused the white dust then and as Simon said you can’t discount the cats etc but lots of things can cause similar.
Even burning oil can cause white deposits especially on valves etc, the thing is , cats have a shelf life and our buses are getting on a bit so we shal always be mindful and discussing the subject
If I could get shut I would ———- bet simon jumps on that comment lol
 
Highway Dave said:
Yeah there’s too many on the market that do nothing good unfortunately.
You may never know what caused the white dust then and as Simon said you can’t discount the cats etc but lots of things can cause similar.
Even burning oil can cause white deposits especially on valves etc, the thing is , cats have a shelf life and our buses are getting on a bit so we shal always be mindful and discussing the subject
If I could get shut I would ———- bet simon jumps on that comment lol
Click to expand...


That’s the part I don’t get, technically you burn hotter/leaner but I guess the engine compensates not to burn leaner lol and the result is burned hole in your wallet.

as for deposits I’ve seen fair amount of manifolds but this one is different for sure, oh well something new.

I cannot wait to finally get rid of my cats and have a look how they looking inside.
 
Ten to one it’s just some kind of oxidisation, if the motor it’s off was sitting around for a long time
I admit it does look different, almost like you’d expect the inlet side to look after being stood
 
WeldHog said:
That’s the part I don’t get, technically you burn hotter/leaner but I guess the engine compensates not to burn leaner lol and the result is burned hole in your wallet.

as for deposits I’ve seen fair amount of manifolds but this one is different for sure, oh well something new.

I cannot wait to finally get rid of my cats and have a look how they looking inside.
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when Steve at Elgrand workshop took my front cats off to decore, he showed them to me and they were in great condition.....and that was at 71k miles that is...but they don't all look that that I'm sure.
 
This is a really helpful post. I had no idea about this problem. Not sure my pockets are deep enough for a full SS system at present though 🤣
 
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