BMW 320D - Excessive smoke on hard acceleration.

Excessive smoke on hard acceleration

This blog started out on the trials and tribulations of car electronics but I've decided to also include my hard won experience learnt from faults on my ageing cars. So this blog post is an 'old chestnut', about excessive smoke from my diesel BMW on hard acceleration.

It's been leaving a smoke screen for some time now but it's been getting worse of late so I decided it needed investigation. Especially since the turbo has developed a whine at low revs that sounds like there is an ambulance with it's siren on following behind.

Blocked crankcase breather a possible reason

As usual I consulted the forums but I've found it's wise to read the contributions with care as they can cause panic and are often ill informed. However, I couldn't help but notice a recurring topic on the subject of BMW crankcase breathers and turbo failure. The engine that my 2005 320D originally used included a filter in the crankcase breather.

Crankcase breather unit

Apparently, this gets blocked (and certainly was) and causes excessive crankcase pressure that causes the turbo bearings to fail, as well as other potential catastrophic dangers such as engine destruction. (The latter is due to oil entering the engine as fuel via the turbo which is then burnt like fuel. As there is no control over it's supply the engine, if in neutral, will rev to destruction! Well that's the story I heard from a couple of sources).

Obviously a known problem. The breather design has been changed.

The car used to be serviced at the dealers and should have been changed previously but advice of some mechanics suggested that this often gets 'overlooked'. Therefore, not wanting to prolong the risk of damage any longer I've just replaced the filter. Importantly the breather design has now been modified to replace the paper filter with a vortex mechanism.

BMW Vortex Filter

It's an intreagueing  design but an easy swap. The breather unit is to be found on the top of the engine just above the air filter.

Hopefully, a long run in the coming week will determine that the problem of smoking has been cured. Fingers crossed! (Unfortunately, the whine is still evident).