Soot in overflow tank

[tree98]

(07-14-2020 )Waterloo Wrote:  Have you inspected the crankcase filter for contamination?

870 doesn't use one.

Your "mechanic" sounds like a complete idiot. You shouldn't be losing coolant until the thermostat opens. If the cooler was the problem and he fixed it correctly it wouldn't be leaking at all and you shouldn't be losing any coolant.