BMW Swirl Flaps

BMW diesel engines produced between 2000 and 2008 all have a particular design issue with inlet manifold butterfly flaps/valves, commonly known as swirl flaps. These flaps are located in the inlet tracts of the intake manifold in BMW diesel M47TU & M57TU engines, having either 4 or 6 flaps depending on the amount of cylinders.


In 2000, BMW manufactured diesel engines with swirl flaps made from steel. In 2004 BMW attempted to address the issue by making the swirl flap spindle thicker and stronger along with larger diameter fixing screws. Unfortunately this modified design is still prone to failure.


These flaps are a poor design and are commonly prone to failing. When they fail and break down they can drop one of the small fixing screws (holding the flap to the shaft) and/or section of spindle or even the flap itself into the engine. The outcome of any associated failure is neither cheap or pretty! Swirl flaps are responsible for numerous destroyed engines and expensive repairs. You could face pistons and valves being damaged, along with injector and cylinder head damage and further damage as debris makes its way out of the engine passing through the turbo and CAT.


We always recommend our customers take the route of preventing the issue rather than chancing the inevitable from happening, depending on a vehicles mileage and/or age or any tell tale oil leaks from inlet manifold area. There is a relatively simple solution to this problem by means of removing the swirl flaps. Once these are removed, the holes will need to be sealed. Using CNC machined blanking plates and fresh gaskets your problem is solved.


Generally 2000-2004 will require 22mm and 2004 – 2008 will require 32mm, however there are examples of later vehicles still fitted with the smaller size. For this reason, we always keep both sizes in stock ready for any eventuality. Post 2009 do not have swirl flaps.


Unlike some garages and examples we’ve seen, we do more than literally just replace the flaps. We remove your inlet manifold which is then extensively cleaned, along with the EGR valve. The swirl flaps are removed and replaced with blanking plates. We refit the manifold using brand new inlet manifold gaskets (these are often over looked elsewhere).


You will not notice any difference in how the car functions without the flaps, they are there for emissions purposes. The car will remain within guidelines and still pass its MOT.