Noisy, rattly or plugged Cat??? Read in...

[GSMGuy]

Well, after all the faults being repaired on my ML - Just got it back after a month at the stealer - all 5 injectors fitted with new seals (again) - apparently they have modified the seal to a compressible washer from the original solid one.... Also the EXPENSIVE alternator replacement... Anyway... The cat started rattling... And at £700 for part alone..... I decided to take matters into my own hands.....

So:

1st step was to remove it from the car, so up on the ramps, a quick spray of WD and away it came - trickiest part was the clamp to the downpipe - Merc have a special tool, I used a 6" G Clamp and a screwdriver.... Same to replace... Perfect

Here is the offending item..

Now to open her up, I chose to open the top so that it would not be visible from underneath the car, I made 2 pilot holes....

Which I then enlarged so I could get my trusty jigsaw in..

Then cut 3 sides of a rectangle..

Before folding back the flap.. And revealing the substrate, mine hadn't broken up - yet, was just loose in the can and annoying me - sounded like a bag of nails...

Used a 19mm spade bit in the cordless to break up the core, took 10 mins..

Leaving the inside all clean - I noticed there is nothing to stop fragments from a broken up cat from passing out into the rear silencer or getting sucked back into the turbo...

Bend it back into shape..

And then had it TIG welded at a local engineering firm - they welded the flap and put a plate over the top just in case...

How neat is that welding!!!

All fitted back, and definate perfomance increase, and no nasty rattle!!!

The cost?? An hour of my time and £20 cash for the welding - BARGAIN!!

Mike

 

[GSMGuy]

BTW, the pics were all taken on my nivce new Sony Ericsson K800i Cybershot PHONE!!! BEst cameraphone I have ever had...

Mike

 

[ADY1983]

What about when your MOT though, will it not fail emissions??
Nice job though...:bannana:

 

[w124coupe]

Chances are it will pass emissions test assuming the o2 sensor is working well BUT will fail IF they spot the hidden repair (rules are that if the car had a cat it must still have a cat and the cat must be intact) - plenty of chat needed to distract the tester on the day!

 

[GSMGuy]

As above - and hence the repair is on the top of the can, so totally hidden from view, even feeling it, it feels ok as the weld is good quality - and it's a brave MOT tester who puts his hand on a hot cat with the motor running!!!

Mike

 

[Dieselman]

It's a diesel so doesn't need a cat to pass the MOT test.

Other than not now having the oxydisation cat you have done the right thing. These cats do not usually clog, they become loose int he can then the gasses pass by the monolith and blow the particles back into the engine.

Let us know whether you have a noticible mpg improvement.

 

[big x]

Good post.On some models with straight pipes you can just bash all the substrate out with a metal rod no cutting required.

adam

 

[230K]

Hi

Any difference in performance or economy, would this empty space affect performance or help it??

Also has the car become smokier at all??

The reason im so interested is i can hear mine rattle at tickover and as i can weld etc i had thought about a staright pipe instead with maybe the old cat welded over the top of it to fool the MOT guys Is it worth the bother of putting a straight through pipe on..

Thanks,

230K

 

[GSMGuy]

230k, definite performance improvement - not sure about fuel economy yet... But also noticed a nice "throatier" exhaust note too....

Mike

 

[stats007]

A throatier diesel is a tractor

A good write-up - just don't do it with a petrol car!

 

[nickmann]

Great phone-pics!!

Are there any issues with handling the substrate? Unpleasant chemicals or nasty dust, that sort of thing?

 

[230K]

Hi

Gutted mine using same method, although used angle grinder instead. Seems sharper on the throttle although exhaust has become tinny.. 2 hours did it from start to finish although i have a 2 post ramp which helps.

I will keep u posted on economy etc


230K