BMW Nikasil issue - FAO M50/M62 engines

[flagellant]

Just stumbled across this on the Net and thought I'd share it with you guys:

What is the “Nikasil issue”?

The “Nikasil issue” is a serious problem that affects all BMW motor cars with engine blocks with “Nikasil” liners in their alloy block when high sulphur fuel has been used. This is 8-cylinder models with the M60 engine made from approximately 1993 to 1996, and 6-cylinder models with the M52 engine made between 1995 and 1998 (note M52 Nikasil engine never went to the USA). The “Nikasil issue” is extremely serious as the final result is a non-functioning engine. The material “Nikasil” is also known as “Galnikal”. "Nikasil" is a very hard dispersion layer of galvanically (electrolytically) applied Nickel applied to the soft alloy bores to prevent wear. If this hard layer is damaged, excessive bore wear occurs rapidly.

Full info @

http://www.lestac.co.uk/bmw/nikasil.htm#affected

[JamesM3M5]

Alusil replaced Nikasil. Alusil is cool because there is silicon in the aluminum. Once the cylinder is bored, they use local heating to get the silicon to precipitate out of the aluminum and harden at the surface (the cylinder wall). This silicon is very hard and durable. Really cool shit.

JamesM

[UD///M]

The issue with the nikasil is that the high sulfur content in some gasoline ( like in the US), the cylinder walls will eventually become pitted. As a result the cylinders can no longer maintain pressure due to the excessive blowby. This would be akin to having rings that have a gap about 4 times larger than max spec. This could lead to piston and total cylinder failure due to the excess wear.