Sorry, long time no reply
80% agree with rttech
but i dont think so that it is due to dust
even 20/17 is look like dirty
I think, something is block in the supply line, which resulting high oil flow back trough re-circulation line,... and increasing the oil tank temperature
Lingga, after main pump is there any by passed filter installed (before going to actuator)?
If yes, may be the by passed valve of the filter which usually shall open when the pressure reach to 5 barg, not open properly.
And resulting high pressure, which make some oil return back through re-circluation line.
have you did venting for all of the valve prior of start up?
is it already solve or still 63 degree C now?