Is the suction filter in the hydraulic tank fully covered that will cause starvation if it is exposed doubt the lid is the problem because there is a breather on top of tank
There is a cylindrical sleeve from the top of the tank that surrounds the filter that forces oil to be drawn from the bottom of the tank. The problem was the seal on the cap was bad, it would draw in air causing the oil to foam up, and then the foamed up oil would push out the breather. The plate I installed with silicone proved that's where the problem was. The owner later on found his parts book and ordered a new cap. He has not had a problem with the oil pushing out the breather since the repair.
