Just changed the thermostat, and found thick black gunge in the housing. After more investigation the expansion tank had bits in and the top radiator pipe which I have now cleaned and flushed. Can anyone suggest the likely cause 118,000 on clock usually great runner. No water in oil and not using water at all???

Pc49, February 2013

if it has an oil cooler then that maybe worth a look,good luck

cdc, February 2013