Adjusting valves can be tricky - as a general rule for the OM617 you are apparently better off leaving the gap on the looser / larger side because over time they have a tendency to tighten (so I'm told).

Ideally you should have the cam lobe pointing directly upwards. Lots of people seem to be very strict about this - I'm not so strict about it because I've measured the cam profile and I know that so long as you are well away from any of the lobe "structure" you're good. But even so - lobe pointing up is best.

Push down on the rocker / cam follower to make sure it is sitting on top of the valve stem as you slide in your feeler gauges.

If you have the light - look through the gap between cam and cam follower to see what it looks like. Sometimes there might be uneven wear... then you have another problem. When I bought my car (from a Mercedes expert) the rocker arm groups were incorrectly installed: On the OM617 there is a group of two rocker arms / cam followers over cylinders 1 and 2. The group of three should be fitted to the back three cylinder positions. If you get these positions reversed I found that the arm that holds the rocker arms in place will bend. This means that the cam followers will be at an angle to the surface of the cam. The cam lobe will then only make contact with a side corner of the follower...

Use the whole set of three spanners when tightening the nuts.

Edit:- I assume your 85 has an OM617...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



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