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Blocked exhaust/cat

Discussion in 'A4/S4 forum(B5 Chassis)' started by turbonutterb, Mar 26, 2009.

  1. turbonutterb
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    turbonutterb New Member

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    [Mar 26, 2009]
    Hi, have been having some boost problems,as stated on previous posts, anyway on a run home from Devon to London earlier this week, the car ,96 1.8t chipped, got slower and slower and was maxing out at 5psi.Then struggling up a hill at 70 mph with my foot buried, there was an almighty noise and a sudden lurch forward!, as I re applied the thottle, obviously I had lifted off completely, It was obvious the exhaust had blown. Although incredibly loud,the car was now running free as a bird and hitting 15 psi plus on 1/2 throttle.A quick stop revealed the cat had blown away from the turbo flange mounting.Now my question, I am using a mates ramp at the weekend for an examination/replacement of the faulty exhaust parts, I wondered if there is a common part that blocks/fails, I'm guessing its the cat,but if anyones come accross a similar problem, a heads up is always useful.Thanks in advance.
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  3. Broken Byzan
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    Broken Byzan Photographic Moderator Staff Member Moderator VCDS Map User

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    [Mar 26, 2009]
    The cat blocking is not unheard of. Also the cat breaking form the flange is quite common.

    You have several options, remove the cat and clear it out, and reweld. That will be ok till next MOT. Or stick a performance CAT on, i believe there to be one on Ebay as we speak. Or just get a pattern replacement at the cost of around £100 iirc
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  4. turbonutterb
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    turbonutterb New Member

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    [Mar 26, 2009]
    Yeah was looking at a clean out and re weld ,initialy at least, just to make sure it is the cat and not another part.Are those sports cats worth fitting, I've seen conflicting reports, or is it just worth fitting a pattern part. I suppose i'll find out of theres any gain, when I clear out the old cat.
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  5. docurley
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    docurley Moderator Staff Member Moderator

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    [Mar 27, 2009]
    I have a Standard CAT for £60 and I'm in London if that helps.
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Mar 27, 2009]
    I took a gutted cat off my car last MOT, and fitted one of these:

    https://sslrelay.com/buypartsby.co.uk/cat_details.php?recordID=816

    Seems to do the job, dunno how it would be on a tuned engine though.

    I still have the gutted cat laying here, can make me an offer for it if you want it, as its been laying in the porch for months.
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  7. Markey
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    Markey Active Member

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    [Mar 27, 2009]
    I have just had my de-cat fitted and the mech said that my old cat had broken and turned round inside blocking the flow. I was suffering from servere under boost having to use lowere gears to get up hills and the car would not go above 80 on the motorway which was terrible.
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  8. g60leigh
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    g60leigh Well-Known Member

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    [Mar 27, 2009]
    mine blew apart at the same time, had it re-welded twice but does not take to well with the different metals of that cat and the flange, worth just replacing straight off, saves the grief
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Mar 27, 2009]
    Markey what do you plan come MOT time? Dodgy tester or swap the real cat back in?

    I didnt actually realise the cat on ours was gutted before i removed it, i just assumed it wasnt working properly. Its probably become blocked and some garage has disemboweled it when it was with the previous owner.

    It was a complete bastard to get off the car though, i ended up putting the grinder thru the downpipe as the cat->downpipe bolts were rotten away and really awkward to get access to, and i was replacing the downpipe anyway. I decided i would just fit the new cat and leave it like that, as the extra 5-10hp that may or maynot be unleashed just wasnt worth the hassle of changing between them.
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  10. docurley
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    docurley Moderator Staff Member Moderator

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    [Mar 27, 2009]
    I have a MillTek down pipe and my Hybrid K04 to install and if I win Marky's Sport CAT I will be all set to go providing Marky stop getting his mates to bump the price up :sly: so I will have two spare CAT's
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  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Mar 27, 2009]
    is the B6 and B5 cat the same?
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  12. Markey
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    Markey Active Member

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    [Mar 27, 2009]
    Im going to get a custome exhaust made anyway with a cat in it. Also my mechanic mate said if you remove the air filter the emissions change and it should pass anyway, its a known trick on some cars that just fail on emissions.
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  13. docurley
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    docurley Moderator Staff Member Moderator

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    [Mar 27, 2009]
    #12

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