No they have mechanical valve actuation. The intake valve tappets are operated directly by the cam lobes with shims, the cam can be removed to replace the shims without disturbing the cam belt, quite clever. The exhaust tappets are actuated via rockers with a grub screw for clearance adjustment.
Thanks. I seem to have quite suddenly developed a top end noise. Does not go away with changes in temperature or oil pressure and is rpm dependent. Sounds like a single tappet judging by the nature of the noise.
Front or rear bank? Either way, you should have no trouble reusing the cam cover gasket. Just take the cover off and have a look. Something must have broken for it to suddenly get noisy. I drove a 12V 164 for 160,000km and never adjusted the valve clearances. Quiet as a mouse.
Have to say that my experience of 12V top end noise & wear was rather less encouraging than S_V's. Not a huge amount of experience I suppose, but of the 3 12V powered cars I actually owned and drove, plus a number I came across owned by friends...they ALL had top end rattle at some point due to exhaust cam lobe and follower excessive wear. The worst one by far was the 12V in my old 155 V6. It went really fast when it went and quickly went from worn out cams and followers to worn out follower bores in the head due to the excessive side loads. The bottom end on that one was iffy as well so I replaced the whole engine. I didn't have it from new, so it's entirely possibly it suffered some neglect or abuse early on that led to the premature failure. Same could be said for the others I owned as well, so maybe I was just unlucky with them all?
Be interesting to see what you find in there..... I maintain that it's a poor design. Inadequate lubrication, unfavorable motion ratio and very narrow cam lobe leading to very high contact pressures and finally, poor materials choice.
You never see cam or follower wear on the 24V engines and inlet cam & follower wear on the 12V is almost unknown as well.
Hope it isn't bad enough to force you into breaking it.
Of course it would be a shame to have to break the car up. I took my chances when I bought it and it seems that luck didn't go my way. I'd love to keep it, but that would most likely be throwing good money after bad.If the top end is toast, I'll probably pull it to bits and see if I can rebuild it over time to put into something else.The rest of the car might make someone else happy.
Chris - my point wasn't that nothing can go wrong, just that in my experience you should never need to adjust clearances in normal use. If it's suddenly gotten noisy, simply adjusting the clearance back to spec is unlikely to fix it long term. Like you said, once something has started wearing, it will usually eat itself to death in no time.