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Cat 303.5e sticky hydraulics
- Thread starter Aaron.ampcon
- Start date
It looks like that valve buts against the piston, and on the other side of the piston there’s two springs that push against the seat which connected to the pin, and that pin is the one that pushes on swash plate.
Short of buying the manual for this machine, that’s the only information I can get on that pump:
https://avspare.com/caterpillar/sebp5957/sebp5957025/#SEBP59570252
https://avspare.com/caterpillar/sebp5957/sebp5957025/#SEBP59570252
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Aaron.ampcon
Well-Known Member
I wouldn’t buy that valve unless I see damage to it and know for sure that’s a problem.
Next is basically your choice, coupler or isolate the pump and pressure test it.
As far as I understood from the previous posts that your problem is low pressure.
So it is either pump or main control valve.
I would test the pump first.
Aaron.ampcon
Well-Known Member
Cant say, never messed with that pump.
Can you share the link where did you found that picture?!
If I am right, and this is an SBS pump, then there should be two socket head bolts on each side of the valve that you posted pictures of.
Possibly if you take those bolts off you might get to the springs.
Although taking pump off, inspecting the coupler and inspecting the valve plate and pistons might be beneficial also.
All depends on your skill set!
Can you share the link where did you found that picture?!
If I am right, and this is an SBS pump, then there should be two socket head bolts on each side of the valve that you posted pictures of.
Possibly if you take those bolts off you might get to the springs.
Although taking pump off, inspecting the coupler and inspecting the valve plate and pistons might be beneficial also.
All depends on your skill set!
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There’s also could be phenomena known as “block lift”, which pertains only to piston pumps. Your valve plate have to be pretty much worn out for that!
I haven’t dealt with that on these duplex pumps, but I just remember stumbling upon information about the Takeuchi mini excavator that had that, and one side was a lot worse than the other!
Which is strange because it is the same piston block and the same valve plate.
Maybe it is have something to do with which row ( inside and outside) and geometrical vectors and physics of forces applied.
The block lift always accompanied by pump overheating, that’s another clue for you.
I haven’t dealt with that on these duplex pumps, but I just remember stumbling upon information about the Takeuchi mini excavator that had that, and one side was a lot worse than the other!
Which is strange because it is the same piston block and the same valve plate.
Maybe it is have something to do with which row ( inside and outside) and geometrical vectors and physics of forces applied.
The block lift always accompanied by pump overheating, that’s another clue for you.
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rmllarue91
Senior Member
Need to monitor load sense pressure at pump. you got a better chance winning powerball than them pumps friction driving and speed related slipping
rmllarue91
Senior Member
Usually internal springs neutral pump. Broken springs would give u pump out pit my experience leads me to believe you have issue with load sense pressure or the regulator is not working
rmllarue91
Senior Member
Block lift should be pressure related first comes on hard digging sounds like this is acting up no loaf
As I admitted before - I never worked on E series of these machines, but: the only pumps that servo piston springs are return to neutral is the closed loop or hydrostatic pumps! And this is definitely not the case!!!
So here is the question: do you for certain know that this is LS pump ( then those springs are bias springs, but still not returning to neutral), or that is what they call a mini excavator duplex pump?!
Aaron.ampcon
Well-Known Member
So an update, I pulled pump coupling is ok
Aaron.ampcon
Well-Known Member
So how do I go about troubleshooting load sense or regulator issue?
Aaron.ampcon
Well-Known Member
I only can say what I would do.
I would open up and inspect, but you have to decide on your own.
Aaron.ampcon
Well-Known Member
Aaron.ampcon
Well-Known Member
Well! It is not duplex pump.
There’s some contamination scratches on the piston slippers. If you can, please post the picture of the piston block where the valve plate rides against, and also wipe the valve plate off and take a picture again, please.
There’s some contamination scratches on the piston slippers. If you can, please post the picture of the piston block where the valve plate rides against, and also wipe the valve plate off and take a picture again, please.
Aaron.ampcon
Well-Known Member
No problem I would have to take the pictures when I'm back at the machine but there were no major or deep digs or scratches if that's what your looking for. Saw some wear on swash plate bearing which I dont think would cause the problems I'm having.
