Webster Hydraulic Fan Motor

[pgchin]

David and Chuck,
Great brainstorming...... after looking at the schematic, I agree with your "assessment". The only other thing I could add is if that filter is original or deteriorated and blocking the fan side....... that and the two valves are the only other items left to try and eliminate. Leroy knows about that solenoid valve in great detail. Alas he is an OTR trucker so I am not sure of his ability to surf the forums while he is working.........
Tommy, can you get more "specific" about what your shop did to the solenoid valve to modify it?
Another suggestion for them to "evaluate". How about getting a length of 5000PSI hose and fittings and bypassing the two valves and filter for a "test"........... show them the schematic and let them "call the ball"....given you cannot find that valve, I do not know of any other way to try and eliminate those 3 items as root cause unless David or Chuck has a better idea. As David cautions, this is extremely high pressure so if a "bypass" test is to be utilized, it MUST be with qualified parts suitable to sustain the pressures of the system.......hose, fittings, connectors, etc..... a good hydraulics shop can handle this as long as you tell them the max PSI the system runs............ FWIW the old lines have the max pressure ratings on them if you can read them.

Chuck, I am going on memory here of over 6 years since I read Leroy's post so I am going to SWAG based on how the 95-97 s60 system works and his old post as the the 95-97's only have 2 speeds, high and low like the 8v's.....that said I "believe" that valve and relief valve works in tandem with a "constant pressure" at all times to spin the fan at low speed (partially open always). When you hit the AC switch OR the temp cooling system sensor trips due to a "certain temp" ( I think Leroy said 190 and he changed it to 180) the valve opens wide open to allow full pressure and high fan speed. In low speed, the fan circuit utilizes the return line for excess pressure....... Again, Tommy, this is a SWAG........let your shop "call the ball".......maybe these tips might trigger some thought or direction for them to utilize. I do remember Leroy wanting that valve ALWAYS open, hence he went with a lower temp "trigger" to make sure it always is full on at regular operating temperature and the fan only spun at low speed while the engine was getting up to operating temp.