ideas please

[tassie wombat]

gday,so ive been chasing a top end/tappet noise for a couple of months now(4.2 tdi)since doing oil change,4 out of 5 days of the week i only do 6 km's to work and the same back home,is it right that diesels can build up crap around pistons,valves etc if they're not driven long enough??? maybe mine just needs a longer drive once in a while?? what does every one think?? thanks.

[Clanky]

Worn tappet pads where they touch on the valve stem and worn rocker shafts / rocker pivot bearings seem to be pretty common. I bought 3 sets before I got a good set to replace mine.
Another problem I found was that the tappets get a groove worn in it from the valve stem. If the feeler gauges are wider than a valve stem you wont get a true setting (bigger gap) as it sits on the high unworn ridge of the tappet. Best to use a thin feeler gauge right on top of the valve.

[tassie wombat]

Worn tappet pads where they touch on the valve stem and worn rocker shafts / rocker pivot bearings seem to be pretty common. I bought 3 sets before I got a good set to replace mine.
Another problem I found was that the tappets get a groove worn in it from the valve stem. If the feeler gauges are wider than a valve stem you wont get a true setting (bigger gap) as it sits on the high unworn ridge of the tappet. Best to use a thin feeler gauge right on top of the valve.

Checked the clearance with a dial indicator,set them at .30mm rather than .35mm.can the pivot bearings be replaced?

[Clanky]

the bearings are not replaceable, however if you were clever with machines you could always make something up.
Replacements new are pricey $65 each from Nissan and 45 each from aftermarket diesel place.
I have no idea what the shafts cost

My tappets are noisy when cold but seem to quieten down when warmed up.