Everyone please repeat after me , THE TENSIONER FOR ALL 928 DOES NOT SELF ADJUST

-- it is mechanical -

a bolt pushes on a pin pushes on the tension arm pushes on the belt -- it does not self adjust , ratchet , click  ,pop, When you tighten the bolt that is it .

The only " adjustment " that it makes is from about 30 slightly cup shaped washers which slightly change shape as they get hot . Before letting a " mechanic " touch your timing belt ask to see the factory tensioning tool , just say you want to see what a $400 tool looks like . If he does not have one .........do not let the " I have done so many that my fingers know how tight " --- Thank him for his time and find another mechanic -- that is the kind of guy who breaks bolts , snaps of the end off the camshaft , can not understand why the belt jumped etc. Once again , THE TENSIONER IS NOT A HYDRAULIC UNIT IT IS MECHANICAL if the tension is set incorrectly , it will stay incorrect . And yes I know the later models hold oil but it is not fed by the engine , you must pour it in , there is no hole in the block to feed oil to the tensioner . The oil assists the transfer of heat from the block to the tensioner and is used as a damper to control flutter of the arm . 

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Alex wrote .....    my mechanic told me that the tensioner automatically adjusts. He told me that the 1500mile retensioning was BS as well.
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Thirty years experience doing something incorrectly hardly makes one an expert . He seems to know a lot about BS
Jim Bailey
928 International