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Blocked Cats..... (On an E39 523i).


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6 replies to this topic

#1 Trisman

Trisman
  • LocationCowfold, Nr.Horsham, W.Sussex.
  • Occupation:Project Management, Construction industry.
  • Current Car:E39 532i Touring. 'E12 M535i.

Posted 17 March 2012 - 03:41 PM

Firstly, does anyone know if this is something that 523i cars are prone to?

(Symptoms are massively reduced performance, no power above a couple of thousand revs, otherwise the engine runs just fine, starts well, idles nicely, no overheating...).

The original Cat was a single, siamesed-entry affair, unlike the twin Cats on the 2.8 M52 engined cars...

(Apparently..) The car in question was overfilled with oil & somehow, that got into the Cat, blocking & pretty effectively wreaking it? That's the theory anyway, though I'm not exactly sure HOW the oil would have got into the exhaust. It's not a diesel!

The car has now had the front portion of a 528i exhaust fitted. This seemed to cure the problem, but occasionally, it still does the lethargic performance thing.

When the exhaust was disconnected to confirm the blocked cat theory, it ran fine, if a little noisy...!

My theory is that there is still some crap in the exhaust blocking it further down the system.

Any thoughts or experience of this? (...DunCAN!).

Edited by Trisman, 17 March 2012 - 03:49 PM.

Trisman.

Current: E39 Touring B10 3.2 Alpinalike in Oxford Green.
Alpina 3.2 engine & gearbox mit flappy paddles. 19" Alpina alloys, spoiler & interior.
M5 Brakes, roof-rail delete & stuff.
E12 M535i Kashmir Gold, 16" open-lug Alpina alloys.

Gonnie:

E31 850CSi Manual V12 insanity in Orient Blau.

E39 540i Manual in Smurf Bloo.

E24 635CSi manual. Grun. Style 5 Alloys, lowered B5 suspension.

E39 '00 530i Imola Red Sport manual.

E39 '98 528i SE Auto Arctic Silver. (237k miles!)
E28 M5 No.8. Weiss. (Now floating around German eBay).
E28 M535i NO2 Monster, Red. Now on this forum! :)
E24 635CSi, Blue,
E28 M5, Lach silver.


#2 Piper

Piper

    #teamdoubleglazing #teamdsp #teamextendedleather

  • Platinum Members
  • 11,612 posts
  • LocationThe Black Country
  • Current Car:E39 523i and 540i

Posted 17 March 2012 - 04:02 PM

Maybe yours is too blocked but I've used Cataclean in the past to keep the cats in good nick

Wanted: perfect Oxford Green 324 panels


#3 duncan-uk

duncan-uk
  • LocationHerts
  • Occupation:I like drawing with crayons and I try not to go outside the lines

Posted 17 March 2012 - 04:29 PM

Well I know of a 523i that blocked it's cat. It was a bang and a rattle. Ran fine but wouldn't pull more than 45! New cat and it was fine.
Posted Image

www.duncanjamesdesign.com

Need arch rolling? Click here! Archenemy

OK I give in I actually quite like the M535i look, especially in white with black wheels


#4 Trisman

Trisman
  • LocationCowfold, Nr.Horsham, W.Sussex.
  • Occupation:Project Management, Construction industry.
  • Current Car:E39 532i Touring. 'E12 M535i.

Posted 17 March 2012 - 04:38 PM

^ ^ No bang, (I got it with the problem) but sounds similar otherwise.

It'd get up to 60~ish eventually, but I had to use the gearbox in manual mode & kinds 'row' it along.
It's better now, but sometimes seems to run out of puff.

Away from rest, I can get the ASC light to flicker, couldn't before....

Course, if the replacement cats are also blocked.... :(

Shame, cos it's quite a nice car.
An 'S' reg Oxford Green Touring, one owner, massive history and... Proper springs on the back!! (No self-leveling to go tits-up!).

Back on the ramp on Monday....

Trisman.

Current: E39 Touring B10 3.2 Alpinalike in Oxford Green.
Alpina 3.2 engine & gearbox mit flappy paddles. 19" Alpina alloys, spoiler & interior.
M5 Brakes, roof-rail delete & stuff.
E12 M535i Kashmir Gold, 16" open-lug Alpina alloys.

Gonnie:

E31 850CSi Manual V12 insanity in Orient Blau.

E39 540i Manual in Smurf Bloo.

E24 635CSi manual. Grun. Style 5 Alloys, lowered B5 suspension.

E39 '00 530i Imola Red Sport manual.

E39 '98 528i SE Auto Arctic Silver. (237k miles!)
E28 M5 No.8. Weiss. (Now floating around German eBay).
E28 M535i NO2 Monster, Red. Now on this forum! :)
E24 635CSi, Blue,
E28 M5, Lach silver.


#5 alpinaman

alpinaman
  • LocationHigh Peak

Posted 17 March 2012 - 04:42 PM

My cat blocked on my 523i..

In fact the inner monolith detached and spun..Partially blocking the exhaust and then reduced performance.

Drop th exhaust off and smash out the monolith with a long bar and a hammer.

Happy days!

f1d45c7f-c6d0-457c-8c0c-4b476ba13e6a_zps130bcd2e-7a6a-45ae-bfb0-567f30f8ad94_zps

 

 

 

 

 

Understeer is when you hit the wall with the front of the car. Oversteer is when you hit the wall with the back of the car. Horsepower is how fast you hit the wall and torque is how far you send the wall across the field once youve hit it.


#6 frankc

frankc
  • Current Car:E39

Posted 18 March 2012 - 10:46 AM

I used to buy a cat cleaner before every MOT and to my mind it worked. Then I read a report on them that basically said you would be better off buying the higher priced unleaded at the pump. Higher Octane? When you pull up the pump you have a choice of two unleaded's just fill it up with the higher priced one and it does the same job. But the advantage of course is that you are getting petrol with your cat cleaner, as opposed to just spending £20 on a good cat cleaner.

At one time I also poured redX, showing my age now, into the carb and it gave out a satisfying cloud of smoke out of the exhaust supposidly it cleared sticking valves and cleaned out gunk from the cats. I am sure many older members on here will remember trying this trick.

Just a couple of extra things to try. Hope it helps.

#7 duncan-uk

duncan-uk
  • LocationHerts
  • Occupation:I like drawing with crayons and I try not to go outside the lines

Posted 18 March 2012 - 12:07 PM

It'd get up to 60~ish eventually, but I had to use the gearbox in manual mode & kinds 'row' it along.
It's better now, but sometimes seems to run out of puff.



Yeh I found using tip and keeping the revs low allowed me to get home after the AA man punctured the cat for me. Mine was definitely fubared!
Posted Image

www.duncanjamesdesign.com

Need arch rolling? Click here! Archenemy

OK I give in I actually quite like the M535i look, especially in white with black wheels





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