Now we get to the pump body itself. You will note it has five o-rings....three large and two smaller. The three larger ones seal the body to the case and isolates the return and bar feed lines. The two smaller ones do not sit in square milled grooves like the other three but rather sit in tapered grooves. These o-rings are small enough that they do not contact the case bore. Under these are holes bored straight through same as the brass barrel. These too are one-way valves in that pressure inside the pump body lift/expands them and allows oil to pass out around them to the bar and/or return, when the pressure receeds on the backstroke of the plunger they seat again in their grooves and seal the pump body from gulping air from the return or pulling oil back from the bar. These o-rings line up one with the bar feed passage and the other with the return passage to the oil tank. The holes under these are prone to becoming clogged. If any of these three one-way valves becomes inoperable the pump won't pump.
In the pic the small o-ring is rolled up out of the groove to show the holes....as you can see from the pic that o-ring is cracked badly so is useless and would cause a problem.
I might as well finish up explaining the oil adjuster and return. In the pic you'll see a plunger and the srew adjuster but missing in the pic is a spring that goes inside the pump body and pushes against the plunger when the adjuster is adjusted inwards.
So...how this works is when the plunger covers the holes in the return passage this is full oiling....adjuster screwed all the way in.......no oil allowed to return to the tank as the plunger blocks the holes. As you back the screw out and expose the holes the o-ring is lifted and more oil is returned oiling to the bar oiling goes down.
Hope this is helpful........and I explained it well enough to follow.
View attachment 1172760View attachment 1172763
