Exhaust regulations

[M Paul Lloyd]

I'm in the process of helping with an exhaust system on a 1994 MkII 2.0 litre Vauxhall Carlton.

A lack of funds precludes a proper pattern replacement at the moment and a previous owner has fitted a fully welded stainless system, which sounds like a nice idea but it includes an infernal cat' ..... welded in too which apparently threw up an 'advisory' on the last MoT!!??

The plan is to cut out the welded cat' and graft flanges onto each end with clamps and bolt in the pattern cat' with said clamps and gaskets until such time as a proper replacement can be procured.

Time was I would not think twice about doing such work as it was always accepted that as long as an exhaust expelled the gases in such a way as not to allow them into the cabin pretty much anything went.

But I am a bit concernered that things may have changed over the years, certainly anything post 2001 is very restricted, so I'm wondering if anyone here could give me a quick run down of current legislation and how it applies to older vehicles?

Thanks.

[TerryG]

Does it need a cat to pass an emissions test? I don't have cats on my 1994 RR (it left the factory with them) and it gets through on petrol with no major problems.

[mr rusty]

All you need to know: http://www.motuk.co.uk/manual_730.htmBut if the cat is working, why change it? I'd wait for the emissions test before mucking about with it.

Emissions tests are a bit weird to say the least:as an example, last year my Rover was pretty marginal- it scraped in with a CO figure of .49%, and over .50% is a fail, and the hc figure was 122ppm, 200ppm being a fail.122 is quite high, I wonder.... could it be worn rings?

These numbers also pointed to a dead or dying cat in the absence of anything else, however, lambda was spot on. Hmmmmm....a shifty garage could easily sell a new cat and lamba sensor off the back of those numbers. I decided however to leave well alone as my voltmeter showed the lambda sensor switching normally.

This year it passed really easily with .00% CO and 49ppm HC, almost as if fluffy green bunnies are hopping out of the tailpipe, despite it's being 16 years old.

The difference? My mot comes up in January, and it's been freezing cold both years, but this year I drove it straight into the test station from my motorway commute, last year I left it down there in the morning. No other changes at all!

[M Paul Lloyd]

Thanks for that link Mr. Rusty much appreciated.

To be honest if it were my car I would be tempted to leave well alone (if it aint broke don't fix it is a good rule I find) as I too have had some really wide ranging emission percentages at MoT's and I am beginning to think that even the weather may have as much bearing on the results as anything else, but its not mine so I'm just going to go with the flow...... no pun intended.

[sierra3dr]

Does it need a cat to pass an emissions test? I don't have cats on my 1994 RR (it left the factory with them) and it gets through on petrol with no major problems.

The said date was 1/8/1992 for cat tests <click here>. But there's the issue when cars have been left on the forecourts and get a late registration,but should have a age related plates

[suffolkpete]

But there's the issue when cars have been left on the forecourts and get a late registration,but should have a age related plates

Surely the registration date is the date of first use, so age-related plates would not be issued in those circumstances.

[sierra3dr]

But there's the issue when cars have been left on the forecourts and get a late registration,but should have a age related plates

Surely the registration date is the date of first use, so age-related plates would not be issued in those circumstances.

This is where it causes problems. For example,if a car is manufactured for the UK market,based on 1991 open loop emissions,and the Dealer wants to get rid and reduces the price and sells it in 1993/94 (K or L reg). The MoT Examiner might test it on a closed loop. But with the latest equipment in most MoT stations,the database might reveal the manufactured year. I imported my 1988 car in 2000,it didn't get 'W' reg but 'F' reg,age related. The definition of 'first use',I surmise it means ownership,and not based on 'first use' in the country

[JPB]

Emissions are tested to whichever's older; the engine or the car.
Example:
Friend brings a kitten to me wanting a fresh engine and MOT work then testing. The engine I sourced actually came from a 1995 Robin, which doesn't need an emissions test as it's a tricycle but, with the engine fitted to the 1976 kitten, which does require emissions test as it has four wheels. In this case, the car was older than the engine, so it was the car's age that was used as the basis of the gas tests.

Example 2:
One of the students has a 1988 mini, so at its tests it would, with the original engine, have had to pass 1988 figures. The engine we had them fit was from a 1962 Cooper, so visible smoke test only for this 1988 car, since the engine was older in this case.

So you see, the emissions testing and whether or not a cat is required is all down to the age of the engine if it's older than the car, or vise-versa.

Read this bit.

[sierra3dr]

A very interesting link there John. But,not all Testers will be inspired to confirm the engine age

[ajsphead]

The Turbo Saab sailed through its MOT yesterday. First use was pre August 1992, so even though it was originally fitted with a CAT, I decided to remove it as the entire exhaust from the manifold back had completely had it. Emissions for CO at 0.637% and HC at 171ppm. The moral here I think is to get the petrol to burn as cleanly as possible, so a good quality air filter, good quality leads, good quality plugs, not necessarily the longest lasting, of the correct type, and a decent exhaust system matter just as much. It also matters that you keep the engine internals nice and clean.

Anthony