Posted by Owen Aaland on July 24, 2014 at 14:24:42 from (216.47.34.49):
In Reply to: 856 MCV pressure posted by Tractorcedric on July 24, 2014 at 13:12:00:
Both pumps draw oil from the same filter. The hitch pump is located directly opposite the filter and is fed through a short jumper tube between the filter cavity and the pump. This tube is normally below the oil level in the transmission and rarely causes problems. The MCV pump draws oil from near the top of the cavity behind the filter inner support plate. From there it goes up a little to the front of the rear frame. Between the rear frame and the center section is an O-ring with a spacer ring to keep the O-ring from collapsing. This O-ring is above the normal oil level and after a few years it can harden and take a set so that it no longer seals as it should. Adding the additional five gallons of oil raises the oil level above this O-ring.
The other place that can leak air is on the filter end of the oil pickup tube. The inlet end is near the bottom of the rear frame between the axles. The outlet is in the filter cavity above the filter. There is an O-ring to seal between the tube and the rear frame that can also allow air to enter. The extra oil will also insure that this O-ring is covered with oil.
Removing the sending unit is not the best way to bleed the air from a troublesome system since the sender is at the end of the hydraulic circuit. No oil will be available there until the system has developed enough pressure to open the pressure regulator valve. Rather remove the plug below the sender that has a 5/8" hex head. That plug is in a port that is fed directly from the MCV through the 3 gpm orifice. Be aware that when oil starts to come out of this port it will exit at 3 gpm and doesn't take long to make a mess.
This post was edited by Owen Aaland at 14:28:01 07/24/14 2 times.
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Today's Featured Article - Hydraulic Basics - Part 2 - by Curtis Von Fange. In the last entry to this series we gave a brief overview of hydraulic system theory, its basic components and how it works. Now lets take a look at some general maintenance tips that will keep our system operating to its fullest potential. The two biggest enemies to a hydraulic system are dirt and water. Dirt can score the insides of cylinders, spool valves and pumps. Wate
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