I have a 1.8 that the po swiched to hydraulic lifters, what's involved in switching back to solid. Engine runs good just starts up and runs loud if I let it sit for a few days.Would rather deal with adjusting valves then hear that noise one more time. Thanks in advance!!!

New cam, pushrods and lifters. Complete tear down.

Have you tried clearing the lifters with a couple of oil changes,don't know about the T4 but this has worked for me on several VW Golf engines.

cheap solutions first

add some "engine elixir" & run it awhile - lots of canned stuff on FLAPS shelves

- or ya can just pour in a Qt of ATF or Marvel Mystery Oil which will usually accomplish the same thing

i most recently, solved this problem on a 1.6 miata with ATF & letting it idle for an hour

and then do an oil & filter change
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X2 on the cam issue - what ya don't know (or tell us) is if the P.O. changed the cam to a hydro grind when he did it - if not, ya got a bigger problem

do a search on The Samba, where there are lots of Type-4 hydro guys

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Have you adjusted the lifters? A misnomer is that once adjusted they never need adjusting again, but that's not true. If you haven't done so already, get the lifters pumped up and readjust. It may shorten the amount of time it takes for that clacking noise to go away.