Hi,

I've got an early 2009 BMW 535d and I'm looking for advice on whether I should remove the swirl flaps or not. The car is currently on 118k miles and has been pretty much trouble free since 72k miles when I bought it. I've done work on it in that time but nothing that wasn't maintenance, wear and tear or some form of optional upgrade.

Now, I'm very familiar with the whole Swirl Flaps saga but what I can't seem to find out is whether any later cars such as mine with the revised plastic flaps have actually failed in the field, and if so what sort of mileage was that at. I don't want to sacrifice MPG or idle smoothness if in practice these later flaps are likely to be fine until 250k miles or something. That said, I do have a set of blanking plugs which arrived today from PMW (not a typo...) along with inlet manifold gaskets etc. I also have a roll of 3.5mm vacuum pipe which I'll be using to replace the existing, perished pipes while the inlet manifold is off as these are in a sorry state in places.

So, the question is, based on first or second hand experience (not internet myth and legend) does anyone have any strong advice either way to remove or keep the swirl flaps? The car is currently running great and returns 43MPG on a decent trip. It would be a shame to lose any of that for no real benefit.

Thanks,
Craig.

Is the 'fact' that you lose idle smoothness and MPG actually internet legend and myth?

I removed the swirl flaps on a 2004 330d and didn't notice any difference in idle or mpg at all. The car felt exactly the same except the nagging feeling that the swirl flaps might fall off had gone from my mind.

Sorry I don't have first hand experience of later cars but I just thought it was worth mentioning.

I've removed the swirl flaps on my 2005 525d they were the plastic type. The car was on 128k at the time and they were in bad way sooted up and starting to fall apart. I have noticed no difference in idle smoothness or mpg.

Another thing to watch out for is the engine and EGR thermostats, they fail stuck open and the engine never gets up to temperature resulting in low mpg and poor performance and because the car doesn't display engine temperature it's hard to spot.

I removed the swirl flaps from my 2006 530d. I noticed little difference in MPG or performance. I also removed the plastic manifold and soaked it for days in a special solution to remove all the coke deposits. If anything the whole experience allowed me to replaced perished seals and hoses, clean the engine bay and check the manifold for cracks.

Also for memory you can interrogate the ecu via the control stalks and bring up the engine temp on the dashboard. I remember finding this from one of the Beamer forums, very easy to do.

[Edited on 6/4/16 by Toprivetguns]

Hi guys, thanks for the prompt responses.

1. I realise it's not a 'fact' that MPG will worsen and/or idle will suffer but the flaps are there for a reason so it seems reasonable to assume there will be some detriment whether noticeable or not. Maybe even just in emissions which it always seems to pass without the machine even detecting a car present! The MOT tester always has to force the machine to start testing because it can't "smell" the car. Good to hear your views on whether the effects of the flap removal is noticeable. Noted.

2. Yes I have already replaced the EGR and main thermostats. That was a fun job when one of the main stat studs sheared on me... Got it out fortunately but not easy! I checked the temps on the hidden dashboard menu and they are all good now. Details here: http://www.meerkats.uk.com/log-book/2015/6/17/thermostat-replacement-egr-and-main-105820-miles

3. Not sure I'll have enough time to soak the inlet manifold in special solvent but will do my best to clean it where I can and if it's really bad then I may reconsider. Hopefully 12k oil changes using Castrol Edge 0w-30 will have helped my cause.

Thanks again - any other opinions out there are most welcome.

quote:

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Originally posted by Toprivetguns
I removed the swirl flaps from my 2006 530d. I noticed little difference in MPG or performance. I also removed the plastic manifold and soaked it for days in a special solution to remove all the coke deposits. If anything the whole experience allowed me to replaced perished seals and hoses, clean the engine bay and check the manifold for cracks.

Also for memory you can interrogate the ecu via the control stalks and bring up the engine temp on the dashboard. I remember finding this from one of the Beamer forums, very easy to do.

[Edited on 6/4/16 by Toprivetguns]

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I was under the impression it stopped being an issue post 2006 as BMW changed the design. I had a 2005 car, and I replaced my plastic flaps with the more robust metal flaps. Worth considering, but i think you will already have metal flaps....

quote:

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Originally posted by twybrow
I was under the impression it stopped being an issue post 2006 as BMW changed the design. I had a 2005 car, and I replaced my plastic flaps with the more robust metal flaps. Worth considering, but i think you will already have metal flaps....

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quote:

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Originally posted by craig1410

quote:

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Originally posted by twybrow
I was under the impression it stopped being an issue post 2006 as BMW changed the design. I had a 2005 car, and I replaced my plastic flaps with the more robust metal flaps. Worth considering, but i think you will already have metal flaps....

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It's the other way around actually - the metal ones were the ones that were a problem and BMW replaced them with plastic flaps with thicker spindles.

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Yeah it's sounding that way.

I need to replace my vacuum hoses for sure as they are breaking up and the only way to get at the full length of the vacuum hoses is to remove the inlet manifold because some of the hoses go beneath it. I got the blanking plugs today and certainly fitting them will remove any possibility of swirl flap ingestion and at the same time prevent any chance of an oil leak developing due to failed inlet manifold or swirl flap seals (I guess it's not an oil leak per se but a condensed oil vapour leak.)

So I guess I don't need to commit to a course of action just yet but will remove the manifold and visually inspect the flaps. If they are badly sooted up and/or showing signs of deterioration then I'll definitely remove them but if they look clean and intact then maybe I'll leave them.

One thing I wondered, due to the fact my vacuum hoses are in poor condition, is whether a vacuum hose failure might leave the flaps in a closed position and then under full engine throttle when presumably they should be fully open, maybe they are being destroyed by the pressure difference across them. I'm not sure if they are spring loaded into the open position and only closed under vacuum (most likely mechanism I would think) or if they are normally closed.

Anyway, I'll hopefully be tackling this and a few other jobs (pollen filters, fuel filter and brake fluid change) at the weekend and will report back how I get on. I just hope I don't have any more sheared studs like when I did the thermostat! I still can't believe that broken as I was using a 3/8th inch stubby ratchet and was holding it fully in the palm of my hand and just twisting my wrist fairly gently. I was stunned when it snapped! Must have a been a chocolate bolt of something!

Thanks again.