Diesels dont need a cat????

[Yugguy]

My Bopra has just failed the mot as the exhaust is blowing at the cat where it joins the rest of the exhaust. The MOT tester said I had 3 options:

weld, but it'd only last six months.
get a new cat.
replace the cat with a pipe as "diesels dont need them".

"will it pass the emissions then?" I asked.
"yes" he says.


This sounds like cobblers to me. I can get an aftermarket cat fitted for 250 quid which will do me on a 9 year old car.

Is he right?

 

[HDi fun]

My Bopra has just failed the mot as the exhaust is blowing at the cat where it joins the rest of the exhaust. The MOT tester said I had 3 options:

weld, but it'd only last six months.
get a new cat.
replace the cat with a pipe as "diesels dont need them".

"will it pass the emissions then?" I asked.
"yes" he says.


This sounds like cobblers to me. I can get an aftermarket cat fitted for 250 quid which will do me on a 9 year old car.

Is he right?

Probably, yes. In fact, no car requires a cat to pass the MoT, it's that it's unlikely to meet the emissions requirements without it/them.

The problem(s) you have, however, is that removal of the cat will almost certainly constitute a modifcation for insurance purposes and the car will be noisier.

 

[lutonmatt]

ya you dont need one for the mot as diesels are test on smoke that is put out

and hdi is right as well is nothing saying you need a cat for petrols if your car runs well and is kicking out the under the limits you are ok

 

[HDi fun]

Diesel emissions are checked (according to age and design) but no diesel car yet has a full closed loop emissions control system.

They probably don't need it - diesels are not throttled (there is no throttle !!). As such they run on excess air. It's impossible to run a diesel engine 'lean'.

In theory then , we might conclude that a diesel engine at idle is running in the cleanest way it can possibly run, at least for MoT testing purposes.

Particle filters are a different matter altogether - Euro IV and Euro V engines attract different requirements.

 

[picassoonwheels]

First off. The catalytic converters in Diesel engines have a different configuration than those in petrol engines.

Next, if you have your engine in perfect/good condition you don't need the cat, as the emission levels would be below the allowed limits anyways. The reason they are present is because "the powers that may be" do not expect you to maintain your engine in top of the line condition, after some years, and thats when your car starts spewing pollutants that bring up a red flag in their hallowed opinion.


Allow me to give you my own example.

I decat me buggy day before and went for a pollution check yesterday.

I found that the reading were lower than what they were when the cat was on. And my buggy is 7 years old.

So if you feel your engine has a clean bill of health, you can go ahead and avoid it by welding a pipe for now, and checking the emission levels after that, which would be easier on the pocket.

And then down the line, you can consider putting in that 250 quid cat, when your engine starts ailing.

Think about it............

 

[HDi fun]

Petrol cars use 3 way closed loop cats.

Derv one are unregulated, I think.

It's highly unlikely that a petrol engine would pass the UK CO test without a cat.

 

[lutonmatt]

lot of the new stuf will pass ok
tested a 5 years old golf the other day failed on the co was something like 0.600 and should be 0.200 to pass the mot he went back smashed the cat out come back and it was reading 0.100

 

[picassoonwheels]

lot of the new stuf will pass ok
tested a 5 years old golf the other day failed on the co was something like 0.600 and should be 0.200 to pass the mot he went back smashed the cat out come back and it was reading 0.100

My reading for CO was 0.1100

So I guess I would pass Mot in UK?.....................

 

[HDi fun]

My reading for CO was 0.1100

So I guess I would pass Mot in UK?.....................

It would - the limit 0.3% But it's still a high reading.

What did the HC reading show? The limit here is 200 parts per million.

My car was jsut tested and read CO at 0.005% and that's done 86,000 miles (which is nothing, to be honest). With (both) cats in place. I don't plan on removing them anyway.

Engine wear in modern cars is really not a problem if correct oil is used; maintenance schedules are followed and drivers are sympathetic to a cold engine's need for gentle driving.

 

[Yugguy]

Gone for the 250 quid cat, I need the car to last another 3 or 4 years.

 

[HDi fun]

Gone for the 250 quid cat, I need the car to last another 3 or 4 years.

A good decision I think. It avoids having to declare another mod to insurers and it'll keep the noise down compared to a straight pipe.

 

[picassoonwheels]

It would - the limit 0.3% But it's still a high reading.

What did the HC reading show? The limit here is 200 parts per million.

My car was jsut tested and read CO at 0.005% and that's done 86,000 miles (which is nothing, to be honest). With (both) cats in place. I don't plan on removing them anyway.

Engine wear in modern cars is really not a problem if correct oil is used; maintenance schedules are followed and drivers are sympathetic to a cold engine's need for gentle driving.

25/m was the HC reading.

Heck if I had me printer going now, I would scan the cert and ask you to decipher it, 'coz I seem to know nothing about this, especially when you pose these question......

It would be a learning experience for me, for sure.

 

[picassoonwheels]

Gone for the 250 quid cat, I need the car to last another 3 or 4 years.

Smart move, if you think you've got a keeper.

While here, the debate progresses....

 

[HDi fun]

25/m was the HC reading.

Heck if I had me printer going now, I would scan the cert and ask you to decipher it, 'coz I seem to know nothing about this, especially when you pose these question......

It would be a learning experience for me, for sure.

That's still a good reading and would get you through a UK test.

 

[picassoonwheels]

That's still a good reading and would get you through a UK test.

Great!

So now tell me................ Are you gonna come to the airport to drive my car home, or do you expect me to drive by meself in a strange land?..........



But I will certainly be posting a scan of the certificate, so you can tell me what all the readings are about.

Hope thats ok wid you?..........

 

[HDi fun]

Great!

So now tell me................ Are you gonna come to the airport to drive my car home, or do you expect me to drive by meself in a strange land?..........



But I will certainly be posting a scan of the certificate, so you can tell me what all the readings are about.

Hope thats ok wid you?..........

Go for it. I'd let Lutonmatt have his say as well - he's our resident tester and will be able to explain the testing procedures very thoroughly in addition to the technicality. I can only cope with the technical bit

 

[lutonmatt]

i can :blink:

 

[HDi fun]

i can :blink:

You'll have to now - I've just nominated you :blink:

 

[picassoonwheels]

Ok Gentlemen! i.e. Lutonmat and HDi Fun

Lemme Invite your attention to the scan of my P.U.C. Certificate, as thats what its called here.



Hope it is clear enough and the bilingual script does not confuse you.

A thousand thanks to you, for clearing my doubts.

 

[yankfan101]

HDI fun, what colour's your 39 mate....

 

[HDi fun]

Steel blue I think it's called.

Pics here.

http://www.torquecars.com/forums/members/hdi-fun-albums-hdi-s-gallery.html

 

[yankfan101]

nope, hav'nt seen that one round Taplow/Maidehead, PS i dont think you should have grown a black tash, it dos'nt go with your blonde curls & manly chest,, ha ha,,,

 

[yankfan101]

Yugguy, check out Fuelcat.co.uk it IS catalist & if you box is going west then this little gaget will do the trick, only £62.oo deliverd....