Crankcase ventilation (Audi 80 B4)

Even a perfectly serviceable engine passes approximately 50-70 liters of gases per minute into the crankcase, formed during combustion of the fuel-air mixture. These gases should be removed from the crankcase to avoid damage to the sealing gaskets. This function is performed by the crankcase ventilation system. The exhaust gases from the crankcase are directed to the air intake or to the air filter, and then are sent for afterburning as part of the fuel-air mixture.

A side effect of crankcase ventilation, which is that the exhaust gases take up some of the engine oil, is beneficial to the engine. These droplets of oil are used to lubricate the inlet valve seat rings, increasing their service life. To prevent the gases from taking away large amounts of oil, a pressure-reducing valve is located on the crankcase ventilation hole on the cylinder head cover.

Attention! A drop in compression with a simultaneous increase in the volume of gases removed from the crankcase indicates wear of the pistons, piston rings and working surfaces of the cylinders.