Hydraulic question- problem solved.Thanks to the help from several on the board I finally found the problem with the 340's hydraulics. It would load the engine down with all valves in neutral. It turned out to be the screen on #10 (in parts diagram) had a hole in it and pieces of the screen were blocking the small orifice. This would not let the regulator valve activate which bypasses the oil flow and reduces the pressure in the system when in the neutral mode. I removed the screen and cleaned and replaced the orifice back in and everything worked perfect. (No screen) Part of the problem in finding the trouble was that the manual labels #10 in the diagram as "safety valve orifice screen and plug". As far as I can see it has nothing to do with the safety valve but does control the flow of oil to the REGULATOR valve. Most, including myself, thought that screen and orifice had something to do with the relief valve circuit. There is a check valve inside the orifice plug, maybe that's a safety valve for something? The screen looked like it was silver soldered on but I could not get it to melt. Must be some type of weld. I was going to cut the bad part of the screen off near the plug and re-attach it. Case- new Holland wants about $50.00 for a new orifice/screen! Guess I am going to have to spring for one. This web site that PAULW-NJ provided described the problem exactly as mine was. Very helpful! >Link A>Link couple of guys noted that it was probably the screen giving the problem. Sure was! Thanks.
When I first checked the screen I saw a small hole in it and not much crud on it at all although it was mostly collapsed. I cleaned it and bent it out as well as I could. Replaced it and of course had the same problem. It was not until I cut the screen off that I could see the small pieces of screen clogging the small orifice. I had the control body apart no less than 5 times! Another fellow mentioned that the controls for changing from single action to dual action cylinders could be the problem if they were not set exactly right in the detents. They didn't make any difference on my system when the screen was plugging the orifice (#10). But when I had the orifice fixed and the regulator valve working properly then the controls for single/dual cylinder did make a difference! If they are turned too far to either side you get the exact same symptom that I started out with!! The engine is lugged down with controls in neutral and speeds up as a valve is operated. Setting the single/dual controls in the right place instantly cures the problem and you can hear the load being taken off the engine. Now with things working properly, just cracking a control valve to where the lift or loader moves slow causes the pressure to go up and the engine lugs down. Opening the valve fully so that the lift rises fast, the load on the engine is less as there is not as much back pressure as with going slow. Returning the valve to neutral the engine speeds up as no load is on it with the pressure regulator doing its job properly. Hope this may help someone else that encounters the same problem. Regards
Gary
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