Helping out a friend who has 1974 1300xl escort, had car rebuilt couple years back, recently said car overheated and asked my advice (as I have old Triumph and Mondy). Rebuilder has moved away and not local, not easy to get car to them.
Coolant flowed out of overflow as car warmed up.
Temp gauge didnt register, put new temp sensor in, gauge registered and coolant flowed out before it indicated "normal" but top hose/rad was cold. Took stat cover off and was staggered to find it was coated in a black gunge. It cleaned in water and lots of black bits and sediment in basin, tested and ok. Put back and this time all was much happier, maybe the gunge was shielding the stat? However (apart from recommending a complete flush) any thoughts? Heard problems mixing antifreeze types altho guy says he hasn't added any, not sure myself...