BMW Swirl Flap removal modification
Swirl flaps are butterfly values in the inlet manifold designed to create a swirl or tumble of the air to aid better combustion under light load. The flaps are fully open during higher load conditions to maximise volumetric efficiency and power output.
The issues occur when the small screws holding the butterflies work loose and find their way into the combustion chamber causing considerable damage. They can also cause damage on their way out of the engine through the turbo and CAT (often a replacement engine is required). A new engine from BMW is in the region of £8,000. If you want more information just search ‘BMW swirl flap failure’ on the internet. Total BMW Magazine also did a feature on this problem in their May 2009 issue.
The engines effected by this problem are M47TU (4 cyl) and M57TU (6 cyl).
Code Introduced Models
M47TUD20 2001 E46 320d, 320Cd, X3 2.0d
M57TUD25 2004 E60/E61 525d
M57TUD30 2002 E46 330d/330Cd, X3 3.0d, X5 3.0d
E60/E61 530d/535d, E65 730d
The solution is to remove the flaps entirely and replace with the blanking plates sold here. You will need one plate per cylinder (so either 4 or 6 per engine).
A free, easy to follow guide can be emailled on request after pruchase. To remove the swirl flaps in my car and replace with the blanking plates took me about an hour and a half, and I didn’t have the guide!
BMW Swirl Flaps are available in 2 sizes, both made from 6000 series aluminium alloy billet and are supplied with replacement Viton seals (as they will be in contact with fuel and elevated temperature).
33mm Blanks are priced at £7.00 ea. Please see other auction for the smaller 22mm blanks they are £6.00 ea.
Postage is free for UK mainland and £12 worldwide, all sent first class recorded delivery
The hole left in the manifold when the swirl flap is removed will be either 22mm or 33mm in diameter (approximately). Please use other auction to order the smaller 22 mm type blanks. There doesn’t seem to be any rule as to which are fitted on particular engines or models (although pre '04 cars seem to generally be the smaller size, but not always) so you may need to order a set of both sizes, the unused set will be refunded if returned in good order by recorded delivery.
The smaller size also fit the BMW engined Opel Omega 2.5 tdi
Although these parts are cheaper than other similar parts avaliable from alternative suppliers they are by no means inferior and perform exactly the same function.
When returning parts please include details of who you are otherwise refunds will be delayed!