Signs of a failing cat? (4200)

[jezbrown1]

Was reading some advice on here and some people have mentioned failing cats as being an issue.
Forgive the potentially dim question but what are the signs?
I've had one fail before, on a 156 GTA, properly fail and pretty much block the exhaust, equalling no power, and I'd rather catch any issue before that!

 

[allandwf]

Unfortunately they don't give many signs. They can rattle but the honeycomb needs to be pretty broken up to get to that point, and likewise if they block up, again there are not many symptoms early on.

 

[BennyD]

Coughing up blood covered fur Balls?

 

[FIFTY]

When I got my car the Euro spec cats were pretty much hollow, when taken off there was lots of sand (thankfully none got into the engine, oil samples have confirmed this)

Anyway, upon purchase the car popped and banged a lot despite having a standard centre section x pipe resonator it is another sign of failing (more like failed) cats

I had a custom cat section made up with 100 cell race cats as primaries, it was about half the price of Larini but perhaps half the quality(?) I am actually in the process of taking them off to get remade with proper 200 cell E marked (street legal) cats

 

[BennyD]

If it passes the emission test with 100 cells, I’d leave them in.

 

[FIFTY]

If it passes the emission test with 100 cells, I’d leave them in.

Derp... just failed the third MOT since they were installed in August 2016 so no choice. The ones he installed are these: https://www.topgear.co.uk/catalytic...ports-rk-4012-100?mfp=51-cell-count[100 Cell] ceramic so I guess they will degrade quickly only 3 or 3.5 inch diameter so i will be surprised if they are rated up to 220bhp each and even if they are they will be running at their absolute peak... they set off a CEL for cat efficiency so i will be glad to see them removed from the car

I might get larger diameter euro 5 cats for added longevity if they will fit in the space with the way the system has been made... I noticed the large diameter stock secondaries are set off centre so they fit in the section...

 

[BennyD]

How many cats have you got on? 2 or 4?

 

[FIFTY]

Only 2... Did good to pass two MOTs eh? XD

 

[BennyD]

Tame testers; every Maser owner should have one!

 

[GeoffCapes]

My 4200 failed the MOT on noise with two 100 cell sports cats, H pipe and Quicksilver back boxes. Had to take the H pipe off for it to pass.

Too loud apparently.

Which is ironic, as there was a Harley Davidson which had just passed a test and it was twice as loud as my 4200.
Their reasoning is that the Harley sounded that loud from the factory, whereas the 4200 didn't.

Well that makes loads of sense......

 

[Spartacus]

That rubbish . MOT testers can't test for an exhaust that is too loud . They don't have a DB reader for the test . I would have taken it to another test centre and said "Will you fail it for being loud ? " That's what I did . The guy said we don't measure it . Just had a note on the form saying "exhaust too loud "

 

[conaero]

Always find a friendly MOT station and built a relationship with them. You will be surprised what a £2 tray of donuts will get you out of.

 

[FIFTY]

With the exhaust valves open my 4200 is now probably as loud or not far off Geoff capes' old car... but where I took mine really don't care about the noise or the fact the cats are not road legal at all (no E mark). Only fell short on the emissions for me this time.

 

[GeoffCapes]

That rubbish . MOT testers can't test for an exhaust that is too loud . They don't have a DB reader for the test . I would have taken it to another test centre and said "Will you fail it for being loud ? " That's what I did . The guy said we don't measure it . Just had a note on the form saying "exhaust too loud "

They failed it. Something to do with being not a standard exhaust or some sh*t.

 

[Oneball]

That rubbish . MOT testers can't test for an exhaust that is too loud . They don't have a DB reader for the test . I would have taken it to another test centre and said "Will you fail it for being loud ? " That's what I did . The guy said we don't measure it . Just had a note on the form saying "exhaust too loud "

They can and the criteria is:

8.1 Noise
8.1.1 Noise suppression system
You must inspect:

• exhaust silencers
• under-bonnet noise deadening material fitted as original equipment – you don't need to inspect this for Class 3 vehicles

You must use your judgement to assess exhaust noise:

• during the emissions test for the vehicle
• rev the engine to around 2,500rpm or half the maximum engine speed if this is lower on vehicles not subject to an emissions test

Exhaust noise from the vehicle must not be unreasonably above the noise level you'd expect from a similar vehicle with a standard silencer in average condition.

 

[jasst]

I took mine to the place that does my MOT prior to the test to ask if they would fail it for noise, He said 'if I say yes, you will go away and put standard exhaust back on for test, then go away and put noisy one back on after test, so to save you the trouble, don't bother!!' the benefits of having a good relationship with them

 

[redsonnylee]

Always find a friendly MOT station and built a relationship with them. You will be surprised what a £2 tray of donuts will get you out of.

Agree totally, I did my mot locally this year, dropped off at 07.30 and picked it up at 08.30 leaving a box of quality street. Smiles all round.