Quote:
Originally Posted by DTP1980
This is very interesting and I'm happy to stand corrected. The link doesn't make it clear whether that's water or oil feeds, but it certainly seems too big for oil. In particular, my protection of turbo comments relate (made unclearly) about the bearings. They MUST be being fed by oil to lubricate and cool. What info is available on that? I can't believe they are ceramic besrings which require, as I understand it, less 'care'.
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Actually, I was surprised that the N47/N57 weren't "upgraded" with electric water pumps - my M57 and your N47 both rely on oil cooling for the turbo(s), as opposed to water cooling on the gas (petrol) engines (N54, N55, N20). All of them have oil to lubricate them, and in the case of the diesel engines, cool them. My guess that the operating regime is different enough that oil is all that's needed, and all the diesel engines have oil coolers (actually water-to-oil heat exchangers).
In any case synthetic oil is one of the reasons BMWs have few turbo bearing failures.