Bmw E39 2.5 exhaust rattle - solved

[Brian.G]

This starting noising the last day, got to the root of the problem this evening, I'll let the video do the talking,

http://www.youtube.com/watch?v=dNC5T4166vc


So I cut it in halves with the hacksaw to have a thin kerf for rewelding length 'tolerance' and half the comb tube is loose or broken - its still stuck in there....so more cutting. The KILLING thing is its completely plugged/blocked. I have no idea how the exhaust was getting through it. Im not sure what to do now - it passed the nct lately with breathable emissions so Im not positive the cat is doing anything at all taking the fact that its blocked into mind. Everything is nice and white so Im guessing spending most time a 6.5K rpm might have something to do with it and its fracture due to it being blocked.
In hind sight the exhaust manifolds were pretty hot of late, as in you would be barely able to look at them after a run.

Pictures of blocked section - it was totally plugged up which is why it cracked off inner tube at end I suspect,

Looked at other manifold to see if it was blocked, and it was - duct taped on the leaf blower to down pipe and there was shocking resistance. So opened up that one too and removed the plugged platinum and rhodium reduction sections from both. These are about 70mm long and infront of the main oxidation honeycomb section. I cant believe these were providing any function so good luck to them. If I have any lights on after Ill be very surprised. If I have, Ill just order two new cats and fit at Christmas - need the car tomorrow...
From the leaf blower tests before and after Im expecting about 20 lost hp to be free'd up(random guess). They are now clear as a whistle.

The loose bit,



80% blocked on both



Removed,





After brain surgery,



Going to re-fit now, cant wait to see how it drives after,

This is the third yoke Ive had that the cats got loose...the 98 transporter being one, Im expecting manifold temperatures to be much less now too with the restriction gone,

So....Its all back and what a difference.....

I clock all my cars from a standing start to a sign near the house. The car now reaches the sign exactly 19mph faster than it did before.
Also seems less labour-some at high revs and sounds 'free'er' around the town.

All in all, very happy, and the bonus - rattles are gone, and no lights on.

Seems like all 192hp are pulling again!


Brian,

[DoktorB]

Get them cut out to feck.

AFAIK the emissions test doesnt test for the gasses that are absorbed by the CAT anyway.

So as long as the tester can still see that there is a thing in which a CAT should be, whether or not a CAT is actually inside isnt something he can tell.

[Valdelisbmw]

Get them cut out to feck.

AFAIK the emissions test doesnt test for the gasses that are absorbed by the CAT anyway.

So as long as the tester can still see that there is a thing in which a CAT should be, whether or not a CAT is actually inside isnt something he can tell.

tester dont care ,u have CATs in or no,it will not pass emission test without them anyway

[DoktorB]

Get them cut out to feck.

AFAIK the emissions test doesnt test for the gasses that are absorbed by the CAT anyway.

So as long as the tester can still see that there is a thing in which a CAT should be, whether or not a CAT is actually inside isnt something he can tell.

tester dont care ,u have CATs in or no,it will not pass emission test without them anyway

My E34 has passed emissions 2 years in a row without the Cats. NCT might be stricter.

[Brian.G]

I was more worried about the post lambda 'noticing' and kicking the engine light if I removed the oxidization section too?

Im hoping it will still pass with the reduction sections removed cos' they could not have been doing anything at this point of degrade?

Yes/no? Lets see!

Brian,

[Lucifer]

Only certain cars will pass the NCT without CAT(s).
The lambda is before the cats in most cars on a closed circut kind of thing. The cats don't affect them (generally imo).

[Brian.G]

Only certain cars will pass the NCT without CAT(s).
The lambda is before the cats in most cars on a closed circut kind of thing. The cats don't affect them (generally imo).

Ya...but Ive 4 lambda sensors on this...two before...two after the cats..surely the post sensor is there to 'see' if the cats are doing their job?