I *may* need to replace the catalytic converter in my 11 year old
Nissan Micra. I have seen some very good prices but also read that
aftermarket cats do not contain precious metals and do not last nearly
as long.

I know about running the car at high revs for 20 minutes to try to
clear the cat and so far this has been successful.

I am wondering if it is possible to recondition a catalytic converter
or to buy a quality unit cost-effectively. I'm guessing that going to
a scrapyard would be illogical as the cats there would be about as old
as mine is.

On Fri, 20 Sep 2019 15:46:50 +0100, Scott wrote:

I *may* need to replace the catalytic converter in my 11 year old
Nissan Micra. I have seen some very good prices but also read that
aftermarket cats do not contain precious metals and do not last nearly
as long.

I know about running the car at high revs for 20 minutes to try to
clear the cat and so far this has been successful.

So why worry?

I've never heard of a catalytic convertors needing that treatment nor
of any engine managemnt system that tells you the catalytic convertor
has been killed. They get killed by unburnt petrol or lead, your not
likely to notice untill the car fails the MOT emmisions test. But as
my last petrol car was about 15 years ago things in that world may
have moved on...

DPF's on the other hand do need the occasional "good run" to burn the
caputured muck out of them and the engine management system may
indicate when this is required. Normally only required if the car is
only used for short stop/start journeys.

--
Cheers
Dave.

On 20/09/2019 15:46, Scott wrote:
I'm guessing that going to
a scrapyard would be illogical as the cats there would be about as old
as mine is.


It's not illogical. Many cars are there because they've been crashed and
may not have done many miles. I don't think cats age.

Another Dave
--
Change nospam to techie

On Fri, 20 Sep 2019 16:37:43 +0100 (BST), "Dave Liquorice"
wrote:

On Fri, 20 Sep 2019 15:46:50 +0100, Scott wrote:

I *may* need to replace the catalytic converter in my 11 year old
Nissan Micra. I have seen some very good prices but also read that
aftermarket cats do not contain precious metals and do not last nearly
as long.

I know about running the car at high revs for 20 minutes to try to
clear the cat and so far this has been successful.

So why worry?

It's just contingency planning at this stage. My concern is that if
the cat fails catastrophically the car will not pass its MOT.

I've never heard of a catalytic convertors needing that treatment nor
of any engine managemnt system that tells you the catalytic convertor
has been killed.

P0420 code stands for “Catalyst System Efficiency Below Threshold
(Bank 1).” When you receive a P0420 code it means your catalytic
converter is not operating at maximum efficiency. Usually this means
your catalytic converter needs to be replaced or there is a problem
with your O2 (oxygen) sensors.
Source: https://exhaustsystemsguide.com/p0420-code/

They get killed by unburnt petrol or lead, your not
likely to notice untill the car fails the MOT emmisions test. But as
my last petrol car was about 15 years ago things in that world may
have moved on...

Yes, but what form does this morbidity take? Is it a case of the
passages becoming blocked or are the precious metals stripped away?

DPF's on the other hand do need the occasional "good run" to burn the
caputured muck out of them and the engine management system may
indicate when this is required. Normally only required if the car is
only used for short stop/start journeys.

Are you saying petrol cars do not require this?

Thanks

Scott wrote:

I know about running the car at high revs for 20 minutes to try to
clear the cat

sure you're not thinking of diesel particulate filters?

Scott wrote:
On Fri, 20 Sep 2019 16:37:43 +0100 (BST), "Dave Liquorice"


DPF's on the other hand do need the occasional "good run" to burn the
caputured muck out of them and the engine management system may
indicate when this is required. Normally only required if the car is
only used for short stop/start journeys.

Are you saying petrol cars do not require this?

He is and I concur.

Tim


--
Please don't feed the trolls

On Fri, 20 Sep 2019 17:39:21 +0100, Andy Burns
wrote:

Scott wrote:

I know about running the car at high revs for 20 minutes to try to
clear the cat

sure you're not thinking of diesel particulate filters?

I wasn't but the person who advised me might have been, I suppose.

"Jethro_uk" wrote in message
...
On Fri, 20 Sep 2019 17:22:58 +0100, Another Dave wrote:

On 20/09/2019 15:46, Scott wrote:
I'm guessing that going to a scrapyard would be illogical as the cats
there would be about as old as mine is.


It's not illogical. Many cars are there because they've been crashed and
may not have done many miles. I don't think cats age.

Well in theory the catalyst is unconsumed in the reaction. So should last
"forever" ...


What about diesel particulate filters? Why do they need to be replaced? Is
it simply that not all the soot is burned off during a high-speed longer
journey, and so it gradually accumulates? Or does something in the DPF
gradually age?

I hope I don't have to have my DPF replaced again in the lifetime of the
car, because it cost about £1000, but then half that was the cost of a new
cat because a thread on the cat that a pipe between DPF and cat screwed onto
got a stripped thread as they were removing the DPF, and the only remedy was
a new cat. I was told (and in light of what people have said in this thread,
I wonder whether I was being told porkies) that the cat was "about due for
replacement anyway" - I wonder if that was just to make me feel better about
having to have a new one.

As with so many things in life, the car is worth a lot more to me as a
working car than its second hand value (which was about £200!) so I stumped
up for the work rather than sell it to the garage as an MOT failure (no DPF
and cat means automatic failure...). And after that "little" job, the car
still goes like a bomb, at 11 years and 190,000 miles old.

Probably a daft question, but what gases does a cat convert in the case of a
diesel? In a petrol, it's oxidising CO to CO2, but since diesels burn the
fuel more completely, there will be virtually no CO. Do diesel cats do
anything to mitigate the amount of NOx by reducing it to N and O?

On Friday, 20 September 2019 15:46:56 UTC+1, Scott wrote:
I *may* need to replace the catalytic converter in my 11 year old
Nissan Micra. I have seen some very good prices but also read that
aftermarket cats do not contain precious metals and do not last nearly
as long.

I know about running the car at high revs for 20 minutes to try to
clear the cat and so far this has been successful.

I am wondering if it is possible to recondition a catalytic converter
or to buy a quality unit cost-effectively. I'm guessing that going to
a scrapyard would be illogical as the cats there would be about as old
as mine is.

https://en.wikipedia.org/wiki/Catalytic_converter

On 20/09/2019 18:18, NY wrote:
"Jethro_uk" wrote in message
...
On Fri, 20 Sep 2019 17:22:58 +0100, Another Dave wrote:

On 20/09/2019 15:46, Scott wrote:
I'm guessing that going to a scrapyard would be illogical as the cats
there would be about as old as mine is.


It's not illogical. Many cars are there because they've been crashed and
may not have done many miles. I don't think cats age.

Well in theory the catalyst is unconsumed in the reaction. So should last
"forever" ...


What about diesel particulate filters? Why do they need to be replaced?
Is it simply that not all the soot is burned off during a high-speed
longer journey, and so it gradually accumulates? Or does something in
the DPF gradually age?

I hope I don't have to have my DPF replaced again in the lifetime of the
car, because it cost about £1000, but then half that was the cost of a
new cat because a thread on the cat that a pipe between DPF and cat
screwed onto got a stripped thread as they were removing the DPF, and
the only remedy was a new cat. I was told (and in light of what people
have said in this thread, I wonder whether I was being told porkies)
that the cat was "about due for replacement anyway" - I wonder if that
was just to make me feel better about having to have a new one.

You can fix stripped threads using helicoils, if you can get to them.
Typically the hardware to do so is about £5 but you need a tap and drill
and if its stainless steel many garages just won't have the stuff.


something like
https://www.screwfix.com/p/helicoil-...4-pieces/265fr

But you need the correct size and some lube.

"dennis@home" wrote in message
...
I hope I don't have to have my DPF replaced again in the lifetime of the
car, because it cost about £1000, but then half that was the cost of a
new cat because a thread on the cat that a pipe between DPF and cat
screwed onto got a stripped thread as they were removing the DPF, and the
only remedy was a new cat. I was told (and in light of what people have
said in this thread, I wonder whether I was being told porkies) that the
cat was "about due for replacement anyway" - I wonder if that was just to
make me feel better about having to have a new one.

You can fix stripped threads using helicoils, if you can get to them.
Typically the hardware to do so is about £5 but you need a tap and drill
and if its stainless steel many garages just won't have the stuff.

I think the problem that the garage had was that the thread stripped in such
a way that they could not get the nut off to use a thread-cutter, nor could
they retighten it so it was gas-tight. I suppose hacksawing the nut at the
12 o'clock and 6 o'clock positions to separate it into two halves would have
a) been labour-intensive (ie costly) and b) risked damaging the thread
beyond the repair of a helicoil.

Anyway, I got a new cat as well as the new DPF I'd budgeted for.

I suppose, given the age of the car, there are a lot of expensive repairs
that I've not had to pay for yet: clutch, shock absorbers, turbo. I've never
had a car before that's still on its original clutch after 190,000 miles.
OK, the bite-point is getting a bit high (presumably the auto-adjuster has
got the end of its adjustment range) but there's no hint of slippage, even
when I had to do a hill-start on a 1:3 hill when the guy in front of me
stalled and then started rolling backwards towards me ;-)

In article ,
Jethro_uk wrote:
I lost count of the number of exhaust manifolds on FIATs (my dad
specialised) that I saw with 3, 2 or occasionally just 1 of the 4 studs
that should hold the downpipe on. SOP for everywhere else was to put an
air wrench on, bang, and "oh dear ...."

Of course once you had broken the stud flush to the cast iron manifold
you were pretty ****ed.

Best ones were from Kwik Fit, who had no choice but to pay the £200 or
so (plus VAT) for us to repair it.

The secret was to use oxy-acetylene to make the *brass* nuts red hot,
and they'd slip off easy. If the stud was over corroded, once you
removed the nut, you made it red-hot and used a stud remover to gently
remove it, and then replace with new studs, proper *brass* nuts, and
locking plates.

I've never had a stud snap where a brass nut was used. As it doesn't
corrode to the stud like a steel one does.

Fairly standard Kwik Fit practice if they find brass nuts to throw them
away and replace with nice shiny new steel ones.

--
*It was recently discovered that research causes cancer in rats*

Dave Plowman London SW
To e-mail, change noise into sound.

On Mon, 23 Sep 2019 11:09:14 -0000 (UTC), Jethro_uk
wrote:

On Sat, 21 Sep 2019 14:37:58 +0100, Dave Plowman (News) wrote:

In article ,
Jethro_uk wrote:
I lost count of the number of exhaust manifolds on FIATs (my dad
specialised) that I saw with 3, 2 or occasionally just 1 of the 4 studs
that should hold the downpipe on. SOP for everywhere else was to put an
air wrench on, bang, and "oh dear ...."

Of course once you had broken the stud flush to the cast iron manifold
you were pretty ****ed.

Best ones were from Kwik Fit, who had no choice but to pay the £200 or
so (plus VAT) for us to repair it.

The secret was to use oxy-acetylene to make the *brass* nuts red hot,
and they'd slip off easy. If the stud was over corroded, once you
removed the nut, you made it red-hot and used a stud remover to gently
remove it, and then replace with new studs, proper *brass* nuts, and
locking plates.

I've never had a stud snap where a brass nut was used. As it doesn't
corrode to the stud like a steel one does.

I wouldn't know. We *always* used acetylene ...

Fairly standard Kwik Fit practice if they find brass nuts to throw them
away and replace with nice shiny new steel ones.

And yet whenever a customer felt like trying to beat us down on price,
they always had a relative who was an expert because they worked at Kwik
Fit ....

Those of us who are of a certain age, can remember when Kwik Fit were
just tyre fitters (exhausts came later). They couldn't even get that
right, and a couple of times we had a call from our local one because a
customer had a Strada (which had a closed rim) and they didn't know how
to change a tyre on one (despite having a machine to do it).

But then PCWorld are "experts", so are Curries. Comet were ... etc etc.

My postman is a football expert!

On Mon, 23 Sep 2019 11:09:14 -0000 (UTC), Jethro_uk wrote:

But then PCWorld are "experts", so are Curries. Comet were ... etc etc.

Sadly they are "experts" when compared against most of the populas.

--
Cheers
Dave.

On 23/09/2019 14:23, Dave Liquorice wrote:
On Mon, 23 Sep 2019 11:09:14 -0000 (UTC), Jethro_uk wrote:

But then PCWorld are "experts", so are Curries. Comet were ... etc etc.

Sadly they are "experts" when compared against most of the populas.

Actually I have found the PFYs in mobile and computer shops to be pretty
well up in their known areas.


--
"Women actually are capable of being far more than the feminists will
let them."

In article ,
Jethro_uk wrote:
I've never had a stud snap where a brass nut was used. As it doesn't
corrode to the stud like a steel one does.

I wouldn't know. We *always* used acetylene ...

I don't have acetylene. But have never had a stud snap where a brass nut
is in place. Steel, often.

Fairly standard Kwik Fit practice if they find brass nuts to throw them
away and replace with nice shiny new steel ones.

And yet whenever a customer felt like trying to beat us down on price,
they always had a relative who was an expert because they worked at Kwik
Fit ....

Hope you don't think I was saying replacing brass nuts with steel is good
practice? No idea why they often do this - perhaps losing the brass ones.
And steel is much cheaper than brass.

Those of us who are of a certain age, can remember when Kwik Fit were
just tyre fitters (exhausts came later). They couldn't even get that
right, and a couple of times we had a call from our local one because a
customer had a Strada (which had a closed rim) and they didn't know how
to change a tyre on one (despite having a machine to do it).

But then PCWorld are "experts", so are Curries. Comet were ... etc etc.

How good any outfit is depends on the individual fitter. And there are
cowboys around everywhere.

--
*Dancing is a perpendicular expression of a horizontal desire *

Dave Plowman London SW
To e-mail, change noise into sound.