1 have a 94 s500 with 190000 a lifter on the left side is ticking and driving us nut!!! I have put in chemical helpers change the oil 2 time in 500 miles made the oil heavier from 40 to 50 can any one tell me how to fiexed or where i can buy a book with illustration of the valve train and what involves changing the lifters on the left side? the car runs great has good oil ps 3 while running and 1to2 while in idle
any ideas or solution will be appriciated thanks in advance

I'm not sure but I think there is a valve adjustment that may correct this. Changing the oil won't. It is possible that one of the lobes on the camshaft has worn and there is excessive clearance causing the noise. Someone here will know.

To answer your questions:
If the valve train is the same as on my 560SEL, (should be, I think), the hydraulic compensators, (fancy name for lifters), hold the rocker arm against the camshaft lobe. On my car, when it began ticking, I discovered the rocker arm had worn where it rides on the cam lobe. A couple of them actually. This makes sense, as cam lobes are hardened in the wear area, causing the rocker arms to wear out first. So, I replaced only a few rocker arms and was back to a quiet valve train. You need a special tool to remove the rocker arms, (on mine anyway). I have heard the rocker arms wearing out will eventually ruin the cam lobe, so you need to get after this repair soon.
If the manual for your model is available on CD, buy it! The one I bought for mine is great! Full of good info. Try Fastlane or partshop above. Seems expensive, but after one or two repairs, it has more than paid for itself!
Good luck!

thanks so much i am working on the cd