If there was a lot of play, that means the valve is either stuck, or bent. It’s a misconception that valves wear loose, they don’t, the valve wears into the seat and that tightens up the clearance
I would either verify with a leak down test or just pull the head
. A leak down test pressurizes the cylinder while it’s at TDC compression
, any leakage is readily apparent, you’ll hear it leaking out of the intake port if the valve is leaking.
The other thing to check when you find loose clearances is for a bent push rod, a stuck valve can bend a push rod, remove the push rod and roll it on a flat surface, if it’s bent you’ll see it immediately.
My bet is your pulling the head
and getting a valve job, I’d have the guides replaced by a machine shop and reamed to size, I like bronze
If you go that route
, do NOT let them talk you into “cleaning” up the head surface unless it’s warped, shaving the head on a Diesel
can get complex
On edit, I should state that I know nothing about your particular motor
, I’m saying things that are the average Diesel
, I’m assuming some things, like your motor
is not an overhead cam for instance