hello all, has anyone any experience of Yan486's consuming coolant?
-there are no external leaks
-the clear header has black gunk in it(not mixed coolant)
-I've seen the TK bulletin on this and have seen and repaired a 486 that packed up because of this
-currently theres three I know of in one fleet all gold engines and one tier 2 486 that another customer has, same


three's a lot in one fleet, as I only work on one fleet!
Should I start building a few 486's for there imminent demise?