Yanmar 2GM20 - Valve Rocker End Float

[SteveIOW]

Checked / adjusted valve rocker arm clearances a couple days ago That went smoothly enough. One thing I did notice though was that one, just one, of the rocker arms had a noticeable bit of play fore and aft along the the rocker shaft. Just wondered if or how this should be corrected. The rocker concerned is the most aft one (No 1 exhaust valve).
Engine over 30 years old now but starts first time and runs well, has good compression and burns no oil.,

 

[BobnLesley]

"...Engine over 30 years old now but starts first time and runs well, has good compression and burns no oil.,"

The very best piece of advice that I ever got with regard to diesel engines, most especially lightly-loaded ones like auxiliary boat engines was:
Notice and remember how it starts; if it starts easily and promptly, and doesn't kick out lots of smoke (white, black or grey) then that engine is happy; as long as it continues to start in that way, then other than regularly replacing filters and renewing the oil... Leave it the feck alone!

 

[VicS]

Checked / adjusted valve rocker arm clearances a couple days ago That went smoothly enough. One thing I did notice though was that one, just one, of the rocker arms had a noticeable bit of play fore and aft along the the rocker shaft. Just wondered if or how this should be corrected. The rocker concerned is the most aft one (No 1 exhaust valve).
Engine over 30 years old now but starts first time and runs well, has good compression and burns no oil.,

are both washers in place at the ends.

 

[SteveIOW]

Yes, both washers inside of shaft end circlips are in place. The fittings on the rocker shaft have never been disturbed.

 

[garymalmgren]

I could be wrong of course, but I suspect that this type of rocker system has end float.
That would mean that all rocker arms would move about the same amount
The OP has mentioned that "just one" moves which is a little strange.
In the diagram, the centre spring pushes against the inner rocker arms. This will draw in the outer units.
If they were meant to be in fixed positions (not sliding laterally) there should be a thrust washer (indicated by the red arrows) between the rocker arm and the "valve arm support., shouldn't there.
Try moving the other rockers and see if they can slide a little too.

gary

 

[Boater Sam]

Unnecessary concern.

 

[fredrussell]

… if it starts easily and promptly, and doesn't kick out lots of smoke (white, black or grey) then that engine is happy; as long as it continues to start in that way, then other than regularly replacing filters and renewing the oil... Leave it the feck alone!

This ^^^