I been made aware that some BMW diesel engines have something called 'swirl flaps' fitted to the inlet manifold (check out vids on Youtube). Apparently these items are prone to falling apart and then get ingested into the engine causing major damage to pistons, valves, cylinder head etc. It seems the remedy is to remove the swirl flaps and fit a replacement blanking plate in their place.

Has anyone experienced or heard of this problem?

Does anyone know what the swirl flaps are supposed to do? They must be part of the engine design for a reason so does removing them have a detrimental affect on power, economy or CO2g/km?

Hi All,

Update on my post asking for info on swirl flaps.

It appears that the function of the swirl flaps is to provide a bit of extra low speed torque/drivability by 'swirling the mixture' as it enters the cylinders.

I have taken the plunge and eventually had them removed and replaced with a set of blanking plates from Swirlflaps.co.uk. I think you would be hard pushed to notice any difference in performance on a standard 3.0SD but I must admit that I can detect just a hint of a flatspot in my re-mapped engine. I think I will have to have it put back on a rolling road and fine tuned to optimise the fuelling. Its been 30K miles since the re-map so it may be a good time to check out how the engine is doing anyway!