The Diesel Swirl Flap really can be one of the biggest threats to your engine. Quite simply, with a weak spindle which tends to fracture under carbon buildup and get sucked into the engine, the engine is at great risk of internal damage.
The BMW diesel engines produced between 2000 and 2008 all have a particular design problem with inlet manifold butterfly flaps (commonly known as swirl flaps). Swirl flaps are used inside the inlet manifold of the BMW M47TU & M57TU diesel engines to vary the length of inlet manifold tract subject to load and anticipated demand. This allows optimum performance to be delivered (on a dynamometer!)
Back in 2000, BMW/Pierburg made a decision to manufacture diesel engine with swirl flaps made from steel. BMW swirl flaps commonly fail in such a way that they either: drop an affixing screw and or the upper section of the spindle. If this does not stop the engine, the remaining swirl flap falling completely into the engine will!
The outcome of swirl flap failure is not pretty in the slightest. Diesel engine pistons cycle at a rate of at least 60 revs per minute, so an ingested metal piece falling off the butterfly flap will be slammed by the moving internal components. Most often, one or more pistons end up severely damaged, along with several valves, an injector and the cylinder head, with possible collateral damage spreading to the turbo as well!
In 2004 the swirl flaps supporting spindle was increased in size, along with the affixing screw diameter. This reduced the number of flap failures but did not eliminate it.
We've found vehicles up to 2007 fitted with the earlier design, so take no comfort from this redesign.
BMW removed the swirl flaps from M57 engines completly after 2007 on some engine models. The same apporach should be taken by ALL owners of M47 or M57 engines or you risk engine failure without warning.
Once swirl flaps are removed, voids of 22mm or 32mm are left in the manifold. These voids need to be sealed, which is where Dragon Auto Works comes in - blanking plates. This is the only professional fix for this problem.
Don't take our word for it, do a quick search for BMW Swirl Flap failure and discove the nightmare that awaits BMW M47 and M57 engine owners.