New MOT rules for diesels: catalytic converter implications

[Brian Kirby]

Shaun - 2011-12-14 11:16 PM

 

There are two columns adjacent to each other.

 

The first is entitled: Method of inspection

The second is entitled: Reason for rejection

 

What I'm seeing is that the item in column 1 is read in conjuction with the corresponding item in column 2.

 

So, the reason for rejection in the second column, item 3: A catalytic converter missing where one was fitted as standard.....

 

......is read in conjuction with item 3 in the first column: On vehicles that qualify for a full cat emissions test, check the presence of the catalytic converter.

 

As there's no full cat emissions test for diesel engines, then the reason for refusal doesn't apply.

 

Well that's how I see it, anyway. Anyone else care to comment?

 

Shaun

For what it is worth, that is my reading as well. It seems quite clear to me. One should not cherry pick within regulations to prove a point, merely read and apply them as written. The acid test, of course, is whether the testers take the same view! Hmmmm! :-)

[Airstream]

Cat bypass pipe details of supplier

 

 

Hello Ray

 

The price including VAT for the decat parts are £78.00 each and then there will only be one delivery charge of £11.95

 

 

If you require more information please email me or call me on 01604 666 705

 

Many thanks

Peter Mcilhiney

 

Online automotive

 

From: sales@onlineautomotive.eu [mailto:sales@onlineautomotive.eu]

 

Ray

[euroserv]

Hello,

 

The above contributions raise a couple of issues;

 

First is that a de-cat pipe is designed to replace the original cat and this may not be enough since most are stolen by cutting the pipes either side of the cat. You may require more than a simple replacement section.

 

Second; I looked at the two items for sale on Ebay and one gives a specific part number. This part number seems correct for the item shown and is indeed a part for the 2.3 Ducato with 120 or 130hp engines but I would dispute whether this is a cat or not.

 

The section offered is known by Fiat as an 'intermediate pipe' which is the centre section below the cat. The cat is installed much higher up against the exhaust manifoldand is identified on Fiat drawings as 'cat'.

 

I think that in many cases the actual cat has not been stolen but because the centre section has been removed and the pipes either side cut you end up having to replace the cat and the middle pipe and the rear pipe and that is why it gets so expensive! The Fiat price for the centre pipe is approx £290+VAT

 

If this is the case and the cat pipe is useless it is worth remembering that you can remove this and take it to a scrap dealer that specialises in catalysers and get some money for it..... I took an old rusty cat to such a dealer on Monday and got £70 for it. It might take the edge off your misfortune a bit.

 

The above also serves to prove that if any garage is going to replace ANY cat for you on ANY vehicle you should ask for the old unit back or get them to reduce the price for a share of the surrender value.

 

Nick

[Trevor S]

Well, I will find out about this in March when my MoT is due because I have had my MH de-cated. Lowlife types have broken into the storage site where I keep my MH three times in the last year. My CAT was stolen on the second break in and cost £700+ to replace. Some months later another break in caused the loss of 7 CATs from other MH's but I was lucky this time. I went to the person who did my first MOT in March 2010 and he said that only a smoke test is necessary. So I found a local firm who have put on a straight pipe fitted with flanges, fitted corresponding flanges to the exhaust either side, and also fitted flanges to the CAT so it can be replaced for the MoT if necessary and then removed again. It just needs 6 nuts and bolts to undo. All for £150 which I thought was well worth the peace of mind as I am sure that the theives have decided the storage site is a profitable repeat target. We have toured the Uk and spent a month in Germany in September and the MH (Renault Master) run great. There is a little smoke when first starting up -especially if left for a couple of weeks or more- but after that no difference in smoke or smell. The man that did the deCAT job tell me that they now get fleets of vehicles in for deCATs as soon as they are new. Fingers crossed for a MoT pass in March.

[Shaun]

Nick, I'm confused by what you've written, because an earlier 'stolen cat' thread from 2010, which you were part of, included a diagram of the X250 exhaust system. I stumbled across that thread today and you thought that part 5 of the drawing, which was the bit on the bottom which gets stolen, is the cat. Have you come across information since then to suggest this isn't the case?

 

If anyone Googles for Fiat parts in relation to this particular exhaust system, there aren't many options about, and the few there are, seem to be located mainly in Germany and Italy. It's very frustrating trying to track down each and every part to see what its called, what its part number is and how much it costs.

 

However, there's an after market supplier in the UK (www.onlineautomotive.co.uk), which would charge £1,125 for the full system. When the parts are broken down (regrettably without pictures), there seems to be a cat near the exhaust manifold, plus another cat, being the one under the chassis which gets stolen. Doesn't this suggest both items are both important parts of this particular emissions system, and both would be referred to as cats by the relevant authorities? The front unit is the more expensive of the two at £528; the other bit which gets nicked is £350 - and these are non-Fiat parts.

 

Going back to the MOT implications, whilst I'd very much like to hear that the part which gets stolen isn't important, and that it's the cat at the manifold (which probably won't be stolen), which is the important part, I suspect that both are equally important in terms of MOT testers checking for catalytic converters.

 

And now for some potentially bad news: I've trawled through a number of random threads, regarding the implications for de-catted diesel vehicles from January 2012. The VOSA manual is far too vague, so even MOT testers are arguing amongst themselves as to what's expected of them. Some say they will not be checking for cats if the vehicle is diesel, whilst others say they'll check regardless of fuel type.

 

I've therefore trawled right back to the source, which is an EU directive, and I very much hope to be proved wrong, but the wording of that makes no differentiation between fuel types, nor terms like 'full cat test' when it comes to the check for a factory-fitted catalytic converter.

 

Furthermore, VOSA's own training course which has been running for MOT testers in the lead up to January 2012, also makes no differentiation between fuel types. It's only when VOSA's test guidance is looked at - as we've doing here - that things change, and in kicks the specific distinction between spark or compression ignition, which determines whether the 'full cat test' is carried out, and thus the potential for failure if the cat is missing.

 

How on earth have VOSA managed to come up with a guidance manual and run related training courses, which leave such doubt in the minds of those at the sharp end of their directives?

 

I'm rather deflated by all of this, and I've written to VOSA again to clarify matters. I've asked them not to tell me about MOT testers and courses, but to spell out the chapter and verse as to what's going on here. I've also mentioned that there are disagreements galore about this, so it's not a matter to be easily brushed off. VOSA's reply to my directness was: "We have forwarded your enquiry to the MOT Technical Standards Team for a response. I will foward their reply once it has been received."

 

Shaun

 

 

 

[flicka]

I had a look on Wikipedia regarding Cats for Diesel engines, as opposed to Petrol

.

Although it's in "US-ese" there are some enlightening points:-

"For diesel engines

 

For compression-ignition (i.e., diesel engines), the most-commonly-used catalytic converter is the Diesel Oxidation Catalyst (DOC). This catalyst uses O2 (oxygen) in the exhaust gas stream to convert CO (carbon monoxide) to CO2 (carbon dioxide) and HC (hydrocarbons) to H2O (water) and CO2. These converters often operate at 90 percent efficiency, virtually eliminating diesel odor and helping to reduce visible particulates (soot). These catalyst are not active for NOx reduction because any reductant present would react first with the high concentration of O2 in diesel exhaust gas.

 

Reduction in NOx emissions from compression-ignition engine has previously been addressed by the addition of exhaust gas to incoming air charge, known as exhaust gas recirculation (EGR). In 2010, most light-duty diesel manufactures in the U.S. added catalytic systems to their vehicles to meet new federal emissions requirements. There are two techniques that have been developed for the catalytic reduction of NOx emissions under lean exhaust condition - selective catalytic reduction (SCR) and the lean NOx trap or NOx adsorber. Instead of precious metal-containing NOx adsorbers, most manufacturers selected base-metal SCR systems that use a reagent such as ammonia to reduce the NOx into nitrogen. Ammonia is supplied to the catalyst system by the injection of urea into the exhaust, which then undergoes thermal decomposition and hydrolysis into ammonia. One trademark product of urea solution, also referred to as Diesel Emission Fluid (DEF), is AdBlue.

 

Diesel exhaust contains relatively high levels of particulate matter (soot), consisting in large part of elemental carbon. Catalytic converters cannot clean up elemental carbon, though they do remove up to 90 percent of the soluble organic fraction[citation needed], so particulates are cleaned up by a soot trap or diesel particulate filter (DPF). A DPF consists of a Cordierite or Silicon Carbide substrate with a geometry that forces the exhaust flow through the substrate walls, leaving behind trapped soot particles. As the amount of soot trapped on the DPF increases, so does the back pressure in the exhaust system. Periodic regenerations (high temperature excursions) are required to initiate combustion of the trapped soot and thereby reducing the exhaust back pressure. The amount of soot loaded on the DPF prior to regeneration may also be limited to prevent extreme exotherms from damaging the trap during regeneration. In the U.S., all on-road light, medium and heavy-duty vehicles powered by diesel and built after January 1, 2007, must meet diesel particulate emission limits that means they effectively have to be equipped with a 2-Way catalytic converter and a diesel particulate filter. Note that this applies only to the diesel engine used in the vehicle. As long as the engine was manufactured before January 1, 2007, the vehicle is not required to have the DPF system. This led to an inventory runup by engine manufacturers in late 2006 so they could continue selling pre-DPF vehicles well into 2007"

 

http://en.wikipedia.org/wiki/Catalytic_converter#For_diesel_engines

 

[euroserv]

Shaun - 2011-12-16 5:21 PM

 

Nick, I'm confused by what you've written, because an earlier 'stolen cat' thread from 2010, which you were part of, included a diagram of the X250 exhaust system. I stumbled across that thread today and you thought that part 5 of the drawing, which was the bit on the bottom which gets stolen, is the cat. Have you come across information since then to suggest this isn't the case?

 

 

Shaun,

 

I am just stating what it says on the notoriously incoherent Fiat parts disc. Due to the 'relatively' low cost of the lower pipe and the fact that the vehicle does not need a cat at all; it seems very unlikely that this is also a cat, making a total of two??

 

I have not actually had to replace any part of a Ducato Euro4 exhaust due to wear so don't know much about the physical components. The only one that had it's pipes stolen was repaired and back on the road in a couple of days and I did not get to examine the parts when they arrived.

 

Nick

[Shaun]

Nick, I've just been looking at the exhaust setup via the X2/50 manual, which has been kindly provided as part of another thread here. I think this tells us what we need to know.

 

The bit which joins the manifold is the pre-catalyzer (which contains the lambda sensor), which is then followed by a flexible pipe. After that comes the catalyzer itself, which is the bit which gets nicked.

 

It seems the system is rather sophisticated, looking at Fiat's description of how it works. Whether or not it's all actually needed appears to be a moot point, but it explains why it's so expensive.

 

I've had further information from VOSA today about this whole MOT malarkey for de-catted diesels. It's starting to make sense but I had to clarify more things, so I won't post until I have the full picture.

 

Shaun

 

[Shaun]

I've carried on this thread with a part 2, as VOSA's reply was too important to be lost in this one.

 

Shaun