freelander 1.8 2001

Hi ,recently bought 1.8 2001 freelander 52,000 miles, mental or not we live in turkey and drove the beast down france swiss italy greece took 5 days to our house after 13hrs italy /greece ferry,we were achieving 37mpg,now here is the cruncher ,the head & timing belt has been done when? but when the engine warms up we have a strange noise, there is no change in the density of the noise(cold engine no noise) not heavier enough for a main bearing ,no misfire starts up hot or cold, oil light is ok used 1ltr oil(10w40) on the trip no problems or end noise on overrun no smoke and we did 160miles of long high mountain roads in greece , it sounds more like on the induction side any clues some suggested an end or another sticky valve lifter but the noise is lower towards the rear of the block,and no I ain't scrapping it , many thanks I wait with baited breathe and in 26deg and sunny sorry