(01-12-2013, 08:51 PM)Taff Wrote: Thanks for that, think i might give it a go, better than buying a new one.. What do you mean Balance' if theres no play in the bearing does it still need balancing?
There will always be a small amount of 'play' in the bearings as there has to be a gap for the oil to flow through, but this 'play' is normally reduced considerably when the oil is being pumped in to the turbo under pressure
As the turbo spins faster and faster (up to 150,000 rpm), it creates vibrations due to heavy spots. If those vibrations are not kept to an absolute minimum, it means the heavy spot in one or more areas puts undue extra force on the bearings which will eventually wear the bearings so that they are no longer round but oval shaped.
This can lead to the compressor and/or turbine wheels touching their housings which will lead to total turbo destruction.
Normally though, you will see obvious signs that something is wrong, like smoke pouring out of the exhaust as the oil passes through the worn bearings in to the turbine side (burning off due to heat) or in to the engine via the compression side (oil being burned during the normal engine running cycle)
If left unchecked, the oil passing in to the compressor side can clog/interfere with the air cooling characteristics of the intercooler, meaning raised air intake temperatures, leading to detonation and destruction of the engine itself.
Diesel engines can withstand a limited amount of detonation (pre ignition) due to diesel having a cooler burning process, where as petrol engines will quickly destroy/melt the pistons in a matter of seconds when detonation occurs.
Balancing normally will add an extra £50+ on to the cost of a turbo rebuild
Just as a footnote, you may want to read this before spending any money.