My GZE's Tappet noise

[heshan]

Guys, my GZE after a even a non-eventful drive, starts giving this "tock, tock, tock, tock.." noise for about another 10 or 20 mins..

My mechanic says this is my tappets making a noise due to not having sufficient lubrication..

My engine has enough and more engine oil and he feels that the engine heats up too much and the engine oil becomes watery and that the tappets run almost on a watery lube..

Can this be? I haven't experienced this before with my engine for an year as its been an year since i put the engine..so I'm not convinced that this is lubrication problem and he suggests I put a oil cooler. I know this will help with the general health of the engine but how can I confirm this problem will be solved before I spend a bit more cash?

Please help.

thanks,
Heshan.