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Decat how hard?

Discussion in 'A4/S4 forum(B5 Chassis)' started by Gunny110, Sep 15, 2013.

  1. Gunny110
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    Gunny110 Member

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    How hard is it to decat a 1.9 tdi? As in do I need to cut with a grinder, or is it all nuts and bolts? Thanks :)
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  2. B5NUT
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    B5NUT Active Member

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    It's nuts & bolts to remove the cat, but depends on the bolts. When I changed the cat on my TDi some of the nuts where rusted and I could not get a socket on them so had to take a grinder to them. You then have to bash the internals of the cat out.
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  3. tonya4
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    tonya4 TDi Powerrrr Moderator

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    My son gutted mine for me,he cut it open,ripped out its guts and welded it back up.Didn't take long.
    tony
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  4. Gunny110
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    Gunny110 Member

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    Thanks lads, I'm just taking mine off and then using a jack handle and a hammer to just crush all the internals up and then empty it. Did you notice much increase I'm performance mpg ect?
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  5. ScottD3
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    ScottD3 I want your faulty electronics

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  6. Gunny110
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    Gunny110 Member

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    Will just gutting the standard cat give the same effect tho?
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  7. ScottD3
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    ScottD3 I want your faulty electronics

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    No idea.
    Not sure you'd get it all out by smacking it?
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  8. Gunny110
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    Gunny110 Member

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    A guy on a rx8 grim said that is what he did
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  9. ScottD3
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    ScottD3 I want your faulty electronics

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    It can be done but I'm not sure how good it would be when compared to a proper decate.

    Thing is, its free, so try it and see how you get on.
    It can't hurt and wont damage the car.
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  10. Gunny110
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    Gunny110 Member

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    I had the cat out of position, but couldn't get to the bolts on the underside of the cat, so couldn't do it :(
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  11. Arrkon
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    Arrkon Midlands regional Moderator Regional Rep

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    I did the "smashy smashy" mod on my 1.8t got all the internals out as it's not actually fixed in place, just held by the Shape of the cat.

    Definate performance increase but I noticed a little more noise over the proper pipe, suspect the gasses have somewhere to expand in there whereas a testpipe doesn't have that.
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  12. Gunny110
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    Gunny110 Member

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    When you have the cat loose, how so you go about getting it out the engine bay?
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  13. jbh
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    jbh TDi lover

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    ive got a spare cat in the garage I'm going to get it cut open and gutted. I might try the smashing option first though.

    on a side note... my old mk4 golf tdi I bought a decat pipe for £60 and took the original cat to the local metal merchant who then checked the number on it and gave me £95 :icon_thumright:

    I was well chuffed
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  14. Arrkon
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    Arrkon Midlands regional Moderator Regional Rep

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    With great difficulty unfortunately... Lots of yanking and kicking the engine up...
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  15. Gunny110
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    Gunny110 Member

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    Lol, I found it very difficult to get to the lower three nuts. So I undone the mid pipe running from the cat, but still I couldn't find any way of getting the cat free
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  16. Gunny110
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    Gunny110 Member

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    Is there a de cat guide anywhere on the forum guys?
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  17. tonya4
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    tonya4 TDi Powerrrr Moderator

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    with the front of the car on ramps,you should be able to wriggle the bit you removed through the engine bay,thats how I removed mine.
    tony
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  18. B5NUT
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    B5NUT Active Member

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    You can get at them you need an extra long socket, I also removed the wheel and the wheel arch liner and had that side of the car up on axel stands. It's not the easiest of jobs but it can be done. One other thing is to buy new nuts as no matter how hard I tightened them up they came lose after a few days.
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  19. Gunny110
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    Gunny110 Member

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    I gained access to the nuts underneath, but the bolts themselves where moving aswel and I couldn't get a spanner on the top, so I gave up. Il try again tonight, but I have no axle stands as of right now.
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  20. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    You need to go in from the drivers wheel area over the driveshaft etc with a stubby spanner, if there anything like the ones on mine there a twat to get at lol but patience will win the fight !!
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  21. Gunny110
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    Gunny110 Member

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    So got tge cat out, but can't get it out the engine bay, help!!
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  22. tonya4
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    tonya4 TDi Powerrrr Moderator

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    what engine have you got?Mines a 115 so the turbo is down,as opposed to afn for example that has the turbo higher.This could be why you can't get the cat out through the bay
    tony
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  23. Gunny110
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    Gunny110 Member

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    I had to do some leave ring, but now it's out. Just need to smash the internals out, oh the joy
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  24. tonya4
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    tonya4 TDi Powerrrr Moderator

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    have fun!
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  25. Gunny110
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    Gunny110 Member

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    Complete jobs a fish, now to see if there is a difference
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  26. jbh
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    jbh TDi lover

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    let us know. as I say its a job ill be doing soon.
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  27. Gunny110
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    Gunny110 Member

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    It's a job well worth doing jb, I've only just done it and can already feel that she pulls more, not much of a change in noise or turbo whistle, but still I've only just done it. And regards to smashy smashy, I didn't even use a hammer. Just a large tent peg (10 mins) I would say do it.
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  28. Gunny110
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    Gunny110 Member

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    I still have that weird rattle tho?
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