7. Clogged Engine Breather

The engine breather system is an important part of the engine. It’s essentially a one-way valve allowing high-pressure blow-by gases from the crankcase to pass through without causing excessive pressure in the oil system. If the system becomes clogged, it’ll allow excessive pressure to build up in the engine, which will then pressurise the turbo system, causing oil to force its way past the bearings. This can result in damage to the bearings themselves, as well as blue smoke emitting from the exhaust.

How to prevent it

For most moderate stages of engine tune, the standard crankcase ventilation system should be able to cope with an increase in engine power whilst continuing to control the emissions from the crankcase. Even on a fairly new car, however, the system should be thoroughly checked and any suspect valves and hoses replaced. For motorsport applications or more radical stages of tune, the worthwhile addition of a remote catch tank will vent excess pressure and collect any oil vapour.