The pump didn’t fail as such, it just had the usual oil leak from the front so I knew it would need at least a rebuild. Turns out it was too far gone.
When I drained the coolant I don’t think there was any oil in it, but it was the green coolant which I believe shouldn’t be used on alloy blocks.
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Color of the coolant is not always a good indicator of the proper coolant. My K75 manual has a statement "Caution Use only antifreeze and corrosion inhibitors free of nitrite!"
As mentioned before I follow Bob Fleicher's recommendation that the coolant
not contain; nitrites, silicates, phosphates and borates.
I was looking at the ingredients of a number of different coolants today and found that Prestone Extended Life, which is green, is the only one that is labeled as being silicate, phosphate, nitrate and borate free. The others including Peak Long-life (phosphate and silicate free), BMW Auto (contains silicates), Motorcraft Gold (sodium nitrate), Prestone DexCool (?) don't do a good job disclosing the ingredients.
What I found is that most do not do a good job of disclosing the ingredients and color is not a good indicator of compatibility with our machines.