SAAB WIS ONLINE

Lubrication/cooling, 4-cyl.

Lubrication/cooling, 4-cyl.



1. Lubrication

2. Cooling


The turbo shaft, which rotates at very high speed, is precisely balanced and runs in "floating" sliding bearing bushes. This means that the bearings require a high flow of oil, so that the shaft floats on an oil film during rotation. The lubricating oil comes from the engine lubrication system through a separate oil line from the oil filter adapter housing. The return oil is carried back to the engine sump. The seal between the shaft and the bearing housing consists of rings (piston ring type) which are fitted in grooves in the shaft.

The turbocharger features water cooling, which reduces the bearing housing temperature by about 100°C (212°F). Lowering the temperature reduces the risk of the oil carbonizing or "coking" and causing subsequent damage. The coolant is taken from the coolant pump via a pipe. After passing through the bearing housing, the coolant is carried to the cylinder head through a pipe. When the engine is switched off and the coolant pump stops pumping, the coolant continues to circulate round the system through the thermosiphon effect.