BMW diesel engine "SWIRL FLAPS" all you ever ever need to know about Swirl flaps!
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    BMW diesel engine "SWIRL FLAPS" all you ever ever need to know about Swirl flaps!

    Swirl flaps are a BMW system to aid cylinder combustion and efficiency on diesels as diesels do not have throttles plates to regulate air/fuel mix, so naturally tend to run between lean and rich conditions wildly because throttle is controlled solely by the fuel injection on diesels..

    A typical early type swirl flap made of metal



    Unfortunately swirlflaps are also a bit of a design abomination as well and responsible for countless destroyed engines and expensive repairs due the flaps disintergrating from fatigue and the metal parts of the swirlflap are ingested into the relevant cylinder of the engine causing catastrophic damage.

    How the swirl flap causes the damage



    Typical engine damage due to swirl flap ingestion



    Swirlflaps are located in the inlet tracts of the intake manifold and are either vacuum (DDE 4,0) or electric actuator (DDE5.0/DDE6.3) controlled by the engine ECU of the car (note on vacuum controlled models failure of the vacuum system results in the swirl flaps defaulting to the open position).

    Effects of faulty swirlflap operation:

    Swirl flaps stuck in open position: Deterioration in exhaust gas characteristics in lower speed ranges otherwise no effect.

    Swirl flaps stuck in closed position: Power loss of approx 10 % at higher engine speeds

    Swirl flap operation



    Swirl flaps operational function basics

    Closed at low engine speeds and low injection volumes (map-controlled)
    The swirl flaps generally open when:
    the coolant temperature < 14 C OR
    the amount of fuel > 24 mg OR
    engine speed > 2250 rpm OR
    the intake temperature < -5 C.


    BMW/Pierburg made a decision to manufacture diesel engine swirl flaps from steel. A Diesel engines piston cycles at least 60 revs per minute, so an ingested piece of the metal swirl flap will be slammed by the moving internal components.

    Most often one or more piston ends up being severely damaged along with several valves, an injector and the cylinder head, with possible collateral damage spreading to the turbo as well - I'm sure you can work out what is the cost of BMW swirl flap failure - several thousand pounds!

    In around 2004, BMW addressed the BMW swirl flap fault; the swirl flap supporting spindle was increased in size along with the affixing screw diameter. However, there have been BMW vehicles registered up to 2007 with early type 22mm swirl flaps fitted) and despite the increased spindle diameter, there have been reports from BMW owners still having swirl flap failure on these cars so it's up to you if you choose to ignore the warnings if you own a later year car!

    BMW diesels engines post 2009 DO NOT have swirl flaps

    The solution remove the swirlflaps and fit blanking plates, performance change is minimal and probably no difference will be noticed and the car will still pass a MOT and drive as normal.

    The engines

    M47 engine(136bhp non common rail vp44 injection pump) DO NOT HAVE swirl flaps

    M47N common rail engine (including M47N/M47TU/M47TUD20)(150bhp face lift model August-September 2001 onwards) has flaps

    M57 engines(M57D)(525d & 187bhp 330d) have no swirl flaps on the manual cars BUT AUTOMATICS DO

    M57N engines(M57TUD)(525d & 330d 204bhp) have swirl flaps both manual and automatics

    BMW 4 cylinders M47 diesels post late 2008 early 2009 are not fitted with swirl flaps anymore, to check your car enter your car chassis number into realoem.com and check your specification, also 6 cylinder N57 diesel engines have a flap control but this is an inline system and not a swirl flap system..


    Failing swirl flaps




    Blanking plates are widely available on the web as are DIYs for your choice of car.

    Typical blanking plates




    Swirl flap removal M57 engine




    Swirl flaps can be removed safely and in most cases when removed properly there is no noticeable loss of performance, but if some performance change is noticed this can be overcome with a tailored remap to compensate for any noticed performance issues and is advisable to have the flaps removed anyway before proceeding or planning a remap of the car as the increased boost pressure will fatigue the swirl flaps even faster.

    Finally a list of BMW cars fitted with swirl flaps engines

    Engine: M47N/M47TU/M47TUD20

    Applications:

    * 110 kW (148 hp) and 330 Nm (243 lbft)
    o E46 320d 2001-2005
    o E83 X3 2.0d (up to end of 2006)


    Engine: M47TU2D20

    The engine was updated again in 2004 as the M47TU2D20. Still at 1995 cc, it produced more power across the range.

    Applications:

    * 120 kW (161 hp) and 340 Nm (251 lbft)
    o E60/E61 520d
    o E87 120d
    o E90/E91 320d
    o E83 X3 2.0d (end of 2006 onwards)



    Engine: M57/M57D25

    M57D25 was introduced in 2000.

    Applications:

    * 166 PS (122 kW; 164 hp) at 4000 rpm, 350 Nm (260 lbft) at 2000-2500 rpm with a 4750 rpm redline, models:
    o 2000-2003 E39 525d *Vehicles With Automatic Transmission ONLY*

    Engine: M57N/M57TU/M57TUD25

    M57TUD25 was introduced in 2004.

    Applications:

    * 177 PS (130 kW; 175 hp) at 4000 rpm, 400 Nm (300 lbft) at 2000-2750 rpm models:
    o E60/E61 525d

    Engine: M57/M57D30

    M57D30, also called M57D29, was introduced in 1998.

    Applications:

    * 184 PS (135 kW; 181 hp)@4000, 390 Nm (290 lbft)@1750-3200 models:
    o E39 530d *Vehicles With Automatic Transmission ONLY*
    o E46 330d/330xd *Vehicles With Automatic Transmission ONLY*
    * 184 PS (135 kW; 181 hp)@4000, 410 Nm (300 lbft)@2000-3000 models:
    o E38 730d *Vehicles With Automatic Transmission ONLY*
    o E53 X5 3.0d
    * 193 PS (142 kW; 190 hp)@4000, 410 Nm (300 lbft)@1750-3000 models:
    o E38 730d
    o E39 530d

    Engine: M57N/M57TU/M57TUD30

    M57TUD30 was introduced in 2002. It originally produced 160 kW (215 hp) at 4000 rpm and 500 Nm (370 lbft) at 2000-2750 rpm, but was tweaked for 150 kW (201 hp) at 4000 rpm and 410 Nm (300 lbft) at 1500-3250 rpm for 2003 and again for 200 kW (268 hp) at 4000 rpm and 560 Nm (410 lbft) at 2000-2250 rpm in 2004.

    Applications:

    * 204 PS (150 kW; 201 hp)@4000, 410 Nm (300 lbft)@1500-3250 models:
    o E46 330d/330Cd/330xd
    o E83 X3 3.0d
    * 218 PS (160 kW; 215 hp)@4000, 500 Nm (370 lbft)@2000-2750 models:
    o E53 X5 3.0d
    o E60/E61 530d/530xd
    o E65 730d
    * 272 PS (200 kW; 268 hp)@4000, 560 Nm (410 lbft)@2000-2250
    o E60/E61 535d

    * 245 PS (180 kW; 242 hp)@4000, 500 Nm (370 lbft)@2000-2250
    * 286 PS (210 kW; 282 hp)@4000, 580 Nm (430 lbft)@2000-2250

    Engine: M57TU2D30

    M57TU2D30 was introduced in 2007, making its debut in the facelifted E60 and E61.

    * M57TU2D30-UL: 197 PS (145 kW; 194 hp)
    * M57TU2D30-OL: 235 PS (173 kW; 232 hp)@4000, 500 Nm (370 lbft)@2000-2750
    * M57TU2D30-TOP: 286 PS (210 kW; 282 hp), 580 Nm (430 lbft)

    Applications:

    * 197 PS (145 kW; 194 hp), 400 Nm (300 lbft) models:
    o E90/E91/E92 325d
    o E60/E61 525d/525xd
    * 231 PS (170 kW; 228 hp)@4000, 500 Nm (370 lbft)@2000-2750 models:
    o E65 730d
    o E90/E91 325d
    o E90/E91 330d/330xd
    * 235 PS (173 kW; 232 hp) models:
    o E60/E61, BMW E70, BMW E71
    * 286 PS (210 kW; 282 hp), 580 Nm (430 lbft) models:
    o E60/E61 535d
    o E70 X5 3.0sd
    o E71 X6 xDrive35d
    o E83 X3 3.0sd
    o E90/E91 335d

    The above data is a basic reference and not cast in stone! If you have any doubts about your engine you should cross reference your cars details on REALOEM.com and examine the inlet manifold page to confirm your cars manifold components list and type and making sure you have the correct transmission option selected.

    The last of the swirl flap engined cars had swirlflaps manufactured fully in plastic so any engine ingestion damage would be minimal but as of yet no decent data is around on this type of ingestion and personally I wouldnt want any sort of plastic either flying around inside a cylinder bore which could end up exiting into the turbo area.
    Last edited by Ronnie; 01-07-2013 at 18:16.
    Essex Turbo

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    An epic wright up but how do I tell what size I need before I strip it all down ?? M57tu

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    Quote Originally Posted by Shadwell View Post
    An epic wright up but how do I tell what size I need before I strip it all down ?? M57tu
    There is no way to be 100% sure what size swirl flaps you have fitted. 99.9% of E46's have the smaller 22mm but I have heard of just one case of the the bigger size fitted to an E46.
    Most sellers will let you order both sizes on the understanding that the unused set will be returned for a full refund

    Sent to the UKs fastest growing BMW Forum.

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    Hi,

    Thank you for this detailed technical report!

    I have a 330d N57... should I have any concerns? I saw you sentence that said....... also 6 cylinder N57 diesel engines have a flap control but this is an inline system and not a swirl flap system..

    Is the inline system not prone to this issue?


    Thanks for you help!

    Colm

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    Exclamation

    Hello,

    I'm planning to buy a BMW and maybe you can help to me with swirl flaps.

    What cars of these ( e39 ) have intake manifold swirl flaps:

    1. BMW 520d. ( 136 hp. ) mechanical gearbox, 2001 y. - 2002 y.
    2. BMW 530d. ( 184 hp. ) mechanical gearbox 2000 y.
    3. BMW 530d. ( 184 hp. ) automatic gearbox, 2000 y.
    4. BMW 530d. ( 193 hp. ) mechanical gearbox 2001 y. - 2003 y.
    5. BMW 530d. ( 193 hp. ) automatic gearbox 2001 y. - 2003 y.

    Many thanks.

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    Quote Originally Posted by saruniukstis View Post
    I'm planning to buy a BMW and maybe you can help to me with swirl flaps.

    What cars of these ( e39 ) have intake manifold swirl flaps:
    1. BMW 520d. ( 136 hp. ) mechanical gearbox, 2001 y. - 2002 y. ~ NO SWIRL FLAPS
    2. BMW 530d. ( 184 hp. ) mechanical gearbox 2000 y. ~ NO SWIRL FLAPS
    3. BMW 530d. ( 184 hp. ) automatic gearbox, 2000 y. ~ SWIRL FLAPS
    4. BMW 530d. ( 193 hp. ) mechanical gearbox 2001 y. - 2003 y. ~ POSSIBLY
    5. BMW 530d. ( 193 hp. ) automatic gearbox 2001 y. - 2003 y. ~ SWIRL FLAPS

    I say possibly for engine no.4 with manual gearbox as this engine is an anomaly, it doesn't have the 204BHP output of the M57N(TU) but theres obviously an upgrade of some description been made to the engine.

    You can usually see the swirl flaps and the control rod if you remove the plastic engine covers and shine a torch
    between the intake manifold and the left hand side of the EGR valve, look on the underside of the intake manifold
    for the flaps & control rod.


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    I will add this about the 3.0d's

    if your not sure if its 184 or 204 hp (check the CC in the V5 log book, 2926cc = 184, 2993cc = 204hp)

    2926CC
    Manuals - no flaps
    Auto - with flaps

    2993cc
    Manuals - with flaps
    Autos - with flaps

    BMW History
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    View my E60 545i Project
    View my E46 320d Tourer Project
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    After reading ABM's detailed thread reference swirl flaps I decided last weekend to check mine my car is as follows....

    BMW 320d E90 M sport 2006

    Engine number- M47N2

    The whole job took about 3 hours including cleaning my EGR valve which wasn't as bad as I expected after seeing other peoples pictures.

    I removed the flaps from the manifold gave them a good clean and inspected them, they didn't seem loose but one thing I did notice was the end of the screws had been rounded, was this a modification to keep them in place, when they fail which part breaks?

    The size of my flaps was 22mm.

    Since cleaning out the manifold/EGR I get roughly 5mpg more.

    Thanks to ABM for his thread
    Attached Thumbnails Attached Thumbnails -flap-jpg   -flat-jpg  

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    Hi
    I have also a BMW 320d E90 M sport 2006 (56 plate).
    From the last post by Micky I was not sure if the swirl flaps were removed or just cleaned. I guess mine will be the same 22mm flaps.
    Do I need to replace these?....

    Also if you have warranty and these fail am I covered?

    Thanks in advance guys.

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    Apologies for the delay in answering your questions ~

    Quote Originally Posted by mickyb1 View Post
    one thing I did notice was the end of the screws had been rounded, was this a modification to keep them in place, when they fail which part breaks?
    The nuts appear to be peined over and historically the flaps broke because literally the screws came loose and the shafts snapped
    before 2004 the swirl flap shafts were only 4mm in diameter this was increased to 4.5mm during 2004.

    Quote Originally Posted by Ash320dM View Post
    From the last post by Micky I was not sure if the swirl flaps were removed or just cleaned. I guess mine will be the same 22mm flaps.
    Looks like Micky put the swirl flaps back into his manifold and yes being the identical engine yours should be 22mm.

    Quote Originally Posted by Ash320dM View Post
    Do I need to replace these?....
    swirl flap failures are relatively uncommon but catastrophic when they occur, damaging the engine so badly a replacement is required so if you remove the flap you remove the risk!

    Quote Originally Posted by Ash320dM View Post
    Also if you have warranty and these fail am I covered?
    Obviously you need to check with your warranty company as each T&C's can differ but removing the swirl flaps may be considered as modifying the engine and in doing so actually invalidate the warranty!

    So to reiterate if you do have a warranty please check to see if :-
    a) you are covered in the event of swirl flap failure & b) removing the swirl flaps will not invalidate the warranty.

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