JC.V8

:I`ve got this metallic noise in timeing with the crank shaft on my 4Ltr disco 2, year 2000 . The noise appears when eng is up to working temp on tick over and vanishes with increase of revs. I think its possibly piston liner movement !what do you think . If this is the case has any one fitted or have any info on ACR V8 Engine Heavy Duty Top Hat Liner System,because i will be looking for a short engine. unsure: