ML 270 CDI Front Catalytic Converter Rattle

[oigle]

I removed the internals of both my cats on the ML270 yesterday, I had a rattle starting towards the back cat and thought I would do it before it became too loud.

No difference to noise unless really looking for it.
Pulls much better, just feels a lot less laboured.

Also, when idling as soon as I had my foot on the gas to keep at a steady speed the rev counter would always say 2100rpm, obviously if I was doing 70 or whatever it would sit higher, but when cruising at 30, 40, 50 etc. to keep that constant it would always be 2100rpm, now it sits at 1500rpm??

So, my EGR is bypassed, my cats are gone and I have a manifold sat here with the flaps already blanked, need to get on and do it really.
I am now seriously considering a remap as well, my old 270cdi Inspiration was mapped and it was so much nicer to drive, after doing the cats yesterday it reminded me of that, made me want to do it.

That can only be a result of running in a higher gear. More efficient engine pulling better at low revs so auto changes up more readily. No other explanation feasible really.

 

[gizze]

I find the rev counter on my ML weird anyway, surely the revs are the revs, but as soon as I press the throttle slightly they climb a lot, or let off the throttle slightly they drop a lot. Unless I have got used to modern torque converters that don't allow so much play?

 

[oigle]

I find the rev counter on my ML weird anyway, surely the revs are the revs, but as soon as I press the throttle slightly they climb a lot, or let off the throttle slightly they drop a lot. Unless I have got used to modern torque converters that don't allow so much play?

Pretty normal at lowish revs. Once above say 2500, they should not climb much with throttle but of course will drop with foot off. The lockup gets more pronounced at higher speeds.

 

[gizze]

Yeah, I think I have just got used to the later 7G boxes and BMWs 8 speed Zf 'box.

Now need to get on and do the Inlet manifold and the engine will be sorted, it runs so well now.
Was having thoughts of swapping for a new Q3, would have cost me around £40 a week to swap, for a brand new car that does 40mpg plus with no warranty issues that is tempting, but driving down to London last night in it I just knew I would miss it too much.

So, manifold, respray the front seats so they look new again, change the diff oils and the transfer case and then decide if I am going to upgrade the suspension.

Been offered a pretty good price on Bilstein rear shocks and springs and their front shocks, but still quite a big outlay for a car this age.

 

[oigle]

Yeah, I think I have just got used to the later 7G boxes and BMWs 8 speed Zf 'box.

Now need to get on and do the Inlet manifold and the engine will be sorted, it runs so well now.
Was having thoughts of swapping for a new Q3, would have cost me around £40 a week to swap, for a brand new car that does 40mpg plus with no warranty issues that is tempting, but driving down to London last night in it I just knew I would miss it too much.

So, manifold, respray the front seats so they look new again, change the diff oils and the transfer case and then decide if I am going to upgrade the suspension.

Been offered a pretty good price on Bilstein rear shocks and springs and their front shocks, but still quite a big outlay for a car this age.

Yep, they cost a bit but they transform the car. Just depends on how long you intend keeping it.

 

[gizze]

I guess that is what I have to decide.
If I get that done then I will need to keep it at least 18 months or so.

 

[stumo]

Do the front shocks first and see what u think. Its a 5 minute job to swap em out. The rears are a massive job. I've not done my rears yet. But the fronts are bilstiens since over 5 years ago. I have mine fully de-euro'd. No cats flaps or egr now. It goes like a rocket.

 

[gizze]

Are the rears a massive job if you buy the Bilstien kit with the spring already mounted?

Maybe I will order the fronts, it needs new track arms as well, the slightest of play when testing the suspension recently, can't notice it on the road but sure I soon will, so maybe I will do them at the same time.

I have a 2.8i Z3 that I am restoring at the moment, and it becomes a real toss up which gets my time and money each week. Just bought some Redline gearbox oil, that is meant to transform the manual BMW 'box, so that will probably get my day off next week.

 

[oigle]

Are the rears a massive job if you buy the Bilstien kit with the spring already mounted?
Maybe I will order the fronts, it needs new track arms as well, the slightest of play when testing the suspension recently, can't notice it on the road but sure I soon will, so maybe I will do them at the same time.

I have a 2.8i Z3 that I am restoring at the moment, and it becomes a real toss up which gets my time and money each week. Just bought some Redline gearbox oil, that is meant to transform the manual BMW 'box, so that will probably get my day off next week.

It is about a 3 hour job to R and R the struts if you have reasonable tools and jacks and are handy. Need stands and a floor jack preferably. 1st time can be tricky to know where to start etc. Took me more hours first time but I can easily do them in 3 now. I experimented with different stuff before finally getting Bilstein so had a few goes at it. Biggest difference is noticed when towing a van - takes all the deep bounce out and makes it much more stable. With standard struts, I had the esp cutting in trying to control the bounce - tore the rear brakes up quickly. No issues at all since fitting the Bilsteins.

 

[gizze]

I have a proper ramp and every tool needed as my farther in law has a garage, so something I will consider.
I will do the manifold first, and maybe the front shocks, as long as that won't feel too odd with just the fronts changed?

And then decide, the rears are the expensive bits at £500 for the pair, and that is trade.

 

[oigle]

I have a proper ramp and every tool needed as my farther in law has a garage, so something I will consider.
I will do the manifold first, and maybe the front shocks, as long as that won't feel too odd with just the fronts changed?

And then decide, the rears are the expensive bits at £500 for the pair, and that is trade.

A ramp is useless. If he has a hoist/lift, that would be great. Doing the fronts will help but will probably make you realise how bad the rears are....at least it will help with steering on rough corners.

 

[gizze]

I meant I can get it on the ramp and lift the rear completely so I can work at a decent height and get underneath it easily.

 

[w8toamg]

I just tapped the outside of the cat with a hammer and bent it slightly until the rattling stopped and it has been sweet ever since

 

[soup nazi]

Stumo
I am now thinking of bashing the ceramic out of my front cat as it has started rattling again. I understand you have done yours, I just wanted to confirm a couple of things from you first. My car is the 2003 with the updated headlights etc and the front cat is shiny stainless about 6 inches diameter and about a foot long. I believe there may be different types fitted depending on the year model. Can you confirm yours is the same?

Also you say you removed the cat and front section of pipe out through the inner guard, i would have thought that it would have either come up through the top (air cleaner removed) or out from underneath.

What did you use to do the bashing and chipping?

Thanks
SN

 

[The Govenor]

Hi SN. I removed mine through the top after taking air cleaner off. Hammer and long chisel make short work of the guts. Only things I found were the clips for the exhaust joints are a pain in the butt and make sure you get a good seal or fumes will be smelt

 

[stumo]

Yes mine is the facelift, the exhaust and cats are the same.

I did mine without removing the air filter, that's why it went out through the inner guard. I just used a hammer and steel rod to smash and punch out the ceramic.

For the exhaust clamps installing, you can lever them out and wedge a nut into each side of the clamp to hold it apart. Then you just tap it onto the joint and the nuts fall out. It makes it way easier to get the clamp on.

 

[soup nazi]

Ok thanks for the advice chaps, I'll be on it next week.

 

[soup nazi]

OK I did the job today, took about two hours to remove the CAT, bash the centre out and refit it. It has made quite a bit of difference to the way the engine runs, its more responsive on the throttle and sounds quieter and cleaner at idle. The exhaust note seems a little lower than it was before but sounds fine with no evidence of howling or whatever until you get over about 3000rpm and give it a foot full, it seems just a little louder in that high range.

The CAT ceramic was intact with about 3mm of play around it and was not blocked at all. Dodgy design really. Overall I am happy with the outcome and I just filled the tank and will report back with the economy figure, I have been getting about 10.2 city cycle.

She's now had;

Double CAT delete
EGR delete
Swirl flap delete