Roy if the hyd motor that drives your radiator cooling fan is going bad how you can verify this problem. Looking at your hyd fan motor and you will see a pressure going in one side and hyd hose across pump housing return hyd hose fluid to tank. Ok now there is one more hyd
hose either on end of hyd motor housing or in center of hyd motor housing. This hose is called case drain and what that means to you.
Disconnect that hose from hyd motor body and start engine hyd oil will discharge from fitting on hyd motor that is telling you your hyd
motor is going bad and hyd oil is bypassing going to what is called case drain. Depending on who built the hyd motor, some can be rebuilt
and some requires replacement. Ran into this problem several times and some of these hyd motors have been discontinued and built
across the pond . my suggestion caterpillar has many different hyd motors that can be retooled to your motorhome fan mount that may
be of interest in case this fan motor replacement gets real involved. Dave Atherton Retired Cat Mechanic