D66-s

[Keatingdemo]

Have a 1998 Komatsu D66S-1, works OK for many hours then
won't go forward or reverse, if you throttle down to a very slow
idle, it will work all day , as soon as you power engine up,
dead stick and no movement, no grinding, slipping , any
ideas? If some 10 weight hyd got put in with the 3o w oil for
transmission would this cause the symptoms. Thanks
 

[AJ.]

That sounds like the charge pump is starving for oil,are the filters and pick up strainer clean,see all the breathers are clear,it must be something small when it works properly some of the time,it is unlikely a little of the 10w oil is the cause but I would drain it and fill it with the correct oil.
AJ