Hello
We've recently had to change out our low/high pressure seals on our cat 3535 and after staring at the pdq design for the unloader valves, I think its wrong...(see pic of pdq m5 pump station design)
Unless a previous owner changed the plumbing which I don't think is the case, pdq has designed the unloader valves (arch and underbody valves) to dump back to the inlet of the 3535. We run our m5 at 1000psi and there is probably 150-200psi going back into the inlet valve along with reservoir tank water.
I see on the cat website for 3535 they also suggest to not feed unloader valves back into the inlet, makes sense to me, this is what I was thinking as I was staring at the plumbing.
Anyone else have recurring cat 3535 seal problems? I was going to try and just increase the length of the bypass hose and feed it all the way up to the reservoir tank (with a diffuser, so I dont cut a water pressure hole in the tank).
We have two cat 3535 pumps, one is a spare. Both have had milky oil problems all the time, we've tried cat oil and other options, always milky but never a problem other than being milky.Oil level never increased or deacresed it just goes milky almost instantly. The one pump we just removed because it started leaking water from manifold onto floor. We changed out the low/high pressure seals and it still leaks, but thats another problem I guess... Seals failing early because of high inlet pressure? maybe...
Makes me wonder if the excessive inlet pressure is the culprit. We also seem to have recurring unloader valve problems where the unloader bearing and tiny o-ring go, maybe because the unloader pressure cant unload fast enough and screws up the unloader as well?
See attached pic, the two red lines are the unloader return lines.
When I say recurring problems, I understand things wear out and require maintenance but it seems too frequent for such a supposedly reliable pump. Our maintenance schedule is rigid and borders on over maintenance but this seems to be a long term annoying problem that could be fixed.
Thanks -
View attachment 860
We've recently had to change out our low/high pressure seals on our cat 3535 and after staring at the pdq design for the unloader valves, I think its wrong...(see pic of pdq m5 pump station design)
Unless a previous owner changed the plumbing which I don't think is the case, pdq has designed the unloader valves (arch and underbody valves) to dump back to the inlet of the 3535. We run our m5 at 1000psi and there is probably 150-200psi going back into the inlet valve along with reservoir tank water.
I see on the cat website for 3535 they also suggest to not feed unloader valves back into the inlet, makes sense to me, this is what I was thinking as I was staring at the plumbing.
Anyone else have recurring cat 3535 seal problems? I was going to try and just increase the length of the bypass hose and feed it all the way up to the reservoir tank (with a diffuser, so I dont cut a water pressure hole in the tank).
We have two cat 3535 pumps, one is a spare. Both have had milky oil problems all the time, we've tried cat oil and other options, always milky but never a problem other than being milky.Oil level never increased or deacresed it just goes milky almost instantly. The one pump we just removed because it started leaking water from manifold onto floor. We changed out the low/high pressure seals and it still leaks, but thats another problem I guess... Seals failing early because of high inlet pressure? maybe...
Makes me wonder if the excessive inlet pressure is the culprit. We also seem to have recurring unloader valve problems where the unloader bearing and tiny o-ring go, maybe because the unloader pressure cant unload fast enough and screws up the unloader as well?
See attached pic, the two red lines are the unloader return lines.
When I say recurring problems, I understand things wear out and require maintenance but it seems too frequent for such a supposedly reliable pump. Our maintenance schedule is rigid and borders on over maintenance but this seems to be a long term annoying problem that could be fixed.
Thanks -
View attachment 860
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