Coolant observation - G05 recommendation

[Gary Knox]

A friend is very active on a professional mechanics website. He posted the following regarding BMW water pumps and the coolant BMW sells/uses. Thought it might be of interest.

Gary--
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Regarding the comment made ,"BMW's that cant keep a water
>pump or thermostat longer than >50K on their coolant." I am
>curious how Mr Lahm sees they fail. BMW has used a huge
>proportion of electrical water pumps for 10 years or so.
>Thermostats as well.

The water pump impeller and T-stat issues that I believe he
was referring to were first used in about 1992 (M50 & M52
engines in particular). By about 2002, those impellers were
upgraded to a superior resin/composite and/or displaced by
newer engines with different pumps (ultimately including
electric).

Electric water pumps greatly reduce the maximum load on the
impeller and reduce energy waste. A belt driven pump must be
large enough to cool an engine at maximum load on the
hottest day. Such a pump is far too large most of the time
and must be throttled back by the T-stat. This is especially
problematic during sudden acceleration in neutral.

BMW cooling system plastics in general have been problematic
(Using G-05 coolant in place of the standard BMW G-48
appears to be helpful). Many BMW specialty shops have
recommended replacement of ALL plastic cooling system
components every two or three years.

G-48 is very much like dexcool with silicates. Those
silicates make a huge difference in cavitation protection
but it's still a short life coolant and the 2EH acid is
still hard on plastic. The G-05 is very similar in
performance/protection but is 2EH free and is a long life
coolant.
Kevin McCartney

[NevadaMike]

I just replaced the water pump on my '91 850i and the impeller on the original one and the Saleri replacement were both cast iron.