Exhaust system blowing 300tdi

[davidlandy]

the exhaust front section on my motor has decided to blow a hole  - its the flexi bit with the braiding on.

mine is fitted with a cat and the section blowing is joined to it GRRRR

the cost of this section with a cat is £260, but its only £20 without!!!

can i replace it with the non cat straight thru system?   what are the implications for the EGR etc.......

thanks
dave

[Ollie]

I'd be interested in the effects of removing the cat too 8)
I know there's probably a sensor mounted in the cat for regulation. If this sensor gets a 'null' reading, what's gonna happen :?:

Cheers.
Ollie.

[davidlandy]

Dont think anybody knows the answer to this question on here!

[hobbit]

One idea would be to cut the pipe and re weld back on leaving the cat in place, with new flexi

Kev

[ChrisW]

David

I think you're problem will be the MOT, vehicles registered after August 1995 require a catalytic convertor to be fitted (I think!)

You could fit a straight through pipe but make sure you have got hold of a cat for mot time, if you know what I mean    

Mine was registered prior to above date and does not have a cat so it is possible.

Not sure what this would do to the lambda/egr sensors - presumably as the gases haven't got to go through the cat then in theory the gases should be moving out a little faster and therefore the temp will be slightly lower?

[davidlandy]

Cheers Chris

I have opted for the safe (but more expensive) route and gone for the same part again.

Think u are right about MOT requiring one

thanks Dave

[matthew]

Having had a browse through

http://www.motuk.com

I can't see any requirement for the MOT that you should have a catalyst at all, only that you need to be able to pass the relevent emmissions test. Construction and Use regs may well require that a catalyst is fitted though.
I'd go and ask a MOT test station, especially with that amount of difference.

[hobbit]

With thought to removing the cat, if it has no sensor on it, you should be ok, as that sensor will hook up to the engine management system (if fitted), and that could be tested by unplugging the sensor and seeing what happens.

Cats for diesels came in later than petrol, still not sure if they are mandatory or not, got to get my mates book out to check.

But surely of there is no prob with engine management, fitting a normal pipe for everyday, and keep a cat for mots would work, buy one between yourselves if it is the same cat, and share it..    

Kev

[Porny]

I know it does not help now, but....

Your Landy does not need the cat; I would have just gone for the no-cat option!

I might stand corrected, but I don't think the 300 Tdi runs a Lambda type sensor, unless it is a late model with the fly by wire controls rather than a cable.  Removing the cat will not have any effect on the EGR.

If the system is fitted with a sensor, then you could have had a boss made up and welded it into the new non-cat pipe! Any exhaust sensor does not need a CAT to work.

Personally, I would remove the EGR set up too or at least block it off.  Without the cat and the EGR, a 300Tdi goes much better.  
My parent’s 300Tdi disco has neither as standard!


Ian


Edited: Just been reading up on the late spec 300 Tdi's and they do not have a lambda or any other type of sensor in the exhaust, which means a non-cat pipe, would be a straight replacement!  
The cat was only initially fitted to some markets that required improved exhaust emissions, and was later carried over to UK spec models.

As far as I am aware, a Cat is not needed for the MOT as a diesel only undergoes a visual smoke check.
In reality, the CAT fitted to 300TDi's is very basic and mainly acts as a soot trap.

I'd personally safe myself over £200 and get the non-cat pipe

[davidlandy]

Ian

where were u 2 days ago?? ohhh bummer

well at least it wont smoke as much!!  .........and im doing my bit for the enviro-thingy

dave

[matthew]

As far as I am aware, a Cat is not needed for the MOT as a diesel only undergoes a visual smoke check.

Not sure where you've been getting diesels tested but every modern diesel I've had tested for a few years (L,M, & R reg) has had a measuring probe shoved up the exhaust, and a printout of the results.
The visual test is for pre 1979 vehicles, engine age doesn't matter, :) my 1962 109" has a 1995 engine.

[Porny]

Hrm, good point.....
(actually knew that thinking about it)
The probe measures exhaust smoke density, which is done whilst accelerating the engine to maxiumum unloaded speed. (hence why you need to ensure your cambelts been changed on time)

Even without a CAT, a 300 TDi should easily be able to pass the emissions test, as long as not too 'tweaked'.

A CAT was only fitted to certain models of the 300 Tdi, and those without the CAT still pass MOT's without any problems. (sorry david)


Ian

[hobbit]

Trust you lot to start talking about broken exhausts, my 200 tdi snapped in half on the extension pipe underneath this morning, wondered why I had a lovely turbo whine.

Did a quick gas weld back together until weekend, got to take pieces off & braise them up properly with a metal sleeve, must admit it sounded nice though

With regards to gas testing, with some machines they only have to rev up once on the fast test, best thing is if timing belt is ok, is to oil and filter change, fuel filter too, wont do any harm to run some diesel injector cleaner through a tank of fuel before the test.

When going to the testing station give it a good run before turning up. Don't just arrive with a one mile jump from cold.

If you fail the test any or all of the above could make the difference.

Kev