Good information and tips.
I was speaking with a fellow 33 owner (who built a 33 race engine with race cams. high compression, ported etc), and he suspects a worn tappet housing cup, he has seen before many times.Conclusion: possible cause: drain the oil with engine hot into a clean container and take a good look
3. Tappet/cam problem
- will be noisy if tappet too loose
Maybe best to have the housings measured more accurately with precise instruments. We're suspecting the one housing near the filter was worn down due to foreign material entering it.
(One thing to mention is that the previous tappet noise started to appear about a month after I put some Motul 300V 15W/50 full synthetic in the engine - this may have cleaned out debris due to it's strong detergents and worn out or blocked the tappet/housing) I changed from Motul 15w/50 semi to Motul 300V full. I noticed a distinct cleaning effect of the oil due to the colour of it.
Guy: Would the gear oil have an effect on a slightly worn tappet sleeve? Maybe cushion the gap?
A likely cause at this point as the tappet in the exactly the same bucket is making the same noise when the engine gets very hot.
They can fix that here by putting new sleeves in.
The tappet support/passages were cleaned out so well I don't imagine the tappet getting blocked with debris, also exactly the same one as before. They were spotless. Used almost half a can of carb cleaner and WD40 for blowing out the passages.
I will probably order some new gaskets anyway, the sooner the better. Payen maybe?
None for boxers in the USA unfortunately. The USA supplier I found has them delivered from the UK anyway!
I saw a web page on this method yesterday. Thanks whizzman.I've cleaned out tappets in the past by slamming them on an old newspaper, on a table top, with the valve-end down. That way, the innards will come out and you can clean them and put them back together again. Be sure to work clean, use fresh engine oil to assemble them and when in doubt about the condition of the parts inside, toss them.
Economically speaking, I am in Uruguay and nothing is slightly cheap here unfortunately whizzman.