2 cats in 2 months, any ideas

[Bud]

I have a 1997 E200 that developed an exhoust rattle. New front section including cat fitted by local (Oswestry) independant garage, 4 weeks later the same rattle returned. My local man fitted another section under warranty and had the emisions re checked and found to be OK. He commented that there did not seem to be much left of the honeycomb inside the cat. Now 3 weeks later it has started again, unfortunately he is now away for 2 weeks. Local tyre garage put it on the ramps this morning and confirmed my suspicions that it had gone again. Can anyone suggest a reason for this ? I dont know the make but cost was just under £200 fitted.

 

[nick mercedes]

I have a 1997 E200 that developed an exhoust rattle. New front section including cat fitted by local (Oswestry) independant garage, 4 weeks later the same rattle returned. My local man fitted another section under warranty and had the emisions re checked and found to be OK. He commented that there did not seem to be much left of the honeycomb inside the cat. Now 3 weeks later it has started again, unfortunately he is now away for 2 weeks. Local tyre garage put it on the ramps this morning and confirmed my suspicions that it had gone again. Can anyone suggest a reason for this ? I dont know the make but cost was just under £200 fitted.

Cheepo copy parts?

 

[Baron_Samedi]

I'd be looking at over-fuelling and the lambda sensor as a start

 

[w124coupe]

Agreed - fix the cause not the effect....

 

[Bud]

Thanx guys but what is a lambda sensor? is it something I can buy and fit or a dealer job

 

[BlackC55]

Cheapo Cats. See it all the time. Fit MB cats generally

 

[w124coupe]

The most likely cause of repeated CAT failure is over-fueling caused by a problem "up stream" of the CAT. The excess fuel causes the CAT to overheat and melt/break down. (it could also be crappy/cheap/poor copy CAT parts of course!!).

You should get the car checked over by a Merc specialist BEFORE putting another new CAT on.

(just checking the emissions at the exhaust is not useful in diagnosing this problem as the CAT, while still alive, will burn the excess fuel leaving the emissions OK - it just won't do it for very long...).

 

[Adam230K]

when i had this problem on my c200 i bought a cheapo crappy cat which rattled after 3 months, and i got it replaced a few times but it still rattled. So i returned it and opened up my old cat, smashed up everything inside it, re-welded and put it back in.

Rattle gone, and MOT passed, and £0 spent.

 

[lynall]

Adam has your car got 2 ox sensors or just the one?



Lynall

 

[Adam230K]

just the 1 (hence why i could do it)

 

[lynall]

Thats exactly why i asked
How do you get on at mot time?


Lynall

 

[recycled]

might be cheapo but MB cats costs over a grand. Is it worth it. I have had cheapo on mine for 2 years now and it has cleared 3 emmisions test so if your car is 1997 it is worth MB cats.
Check the cause of the problem as it would still damage the MB cat

 

[Shude]

Thats exactly why i asked
How do you get on at mot time?

Technically speaking if the car passes the emissions checks and the catalytic converter passes a visual inspection then there should be no issue.

 

[lynall]

So the op could just have a straight through pipe and if it pass,s emissions test he wouldnt need to spend out on a cat?

This is assuming his car is similiar age to adams and has only one ox sensor.



Lynall

 

[Shude]

So the op could just have a straight through pipe and if it pass,s emissions test he wouldnt need to spend out on a cat?

This is assuming his car is similiar age to adams and has only one ox sensor.

Likely! It is also possible to get sensor emulators if the figures from the real sensors are not "within tolerances"