My '89 Tristar showed up in the USA with the usual clattering valves.  I did
the compulsory oil change and ran it for 45 minutes in the garage and 45
minutes on the road at varying speed.  After all that, the valves were still
clattering leaving me with no choice but to pull the valve covers.  I was
hoping to avoid that step because the exhaust system on the 112HP
water-boxer engine comes painfully close to the valve covers.  You pretty
much have to release the bail and then remove the bail completely to get the
valve cover off.

So, after going through all that on the driver's side (cylinders 1 & 2) I
finally got to check the valve adjusters.  WOW!  The adjustments on #1 were
way loose and #2 wasn't much better.  I'm not talking .006 or .008, these
suckers moved a lot (the finger test).  Haven't got to the other side yet.

The next thing I checked were the valve stems.  I figured they had all
mushroomed and I was looking at pulling the heads.  Nope.  They all look
like new.  Next up was the adjusters.  No problems there either.  Faces look
clean and all the nuts were tight.

I'm totally baffled as to how these valves could be so out of adjustment.
Other than an incompetent mechanic, I can't think of one mechanical reason
that would cause loose valves beyond what I've already looked at.  I suppose
the lifters could be experiencing some sort of problem, but it seems
unlikely that all of them would be having the same issue.

Any ideas?

BTW:  It runs like a top, even with the clattering valves, so it's really
unlikely that there's some crap on the valve seats that is not allowing the
valves to close completely.

Cheers,

Jeff