315 BL Cat excavator hydraulic question

Circle K

Member
Hello, I have a 315bl Cat excavator. My hydraulics have been slowing down some when the machine gets warmed up. Machine has a lot of hours so this isn?t a surprise for me, but as far as hydraulic filters, there?s the paper one on top of the hyd tank, and somebody was telling me there might be a strainer somewhere too to clean out? Anybody know about this? Thanks
 
Could be wrong here but if it is on top of the tank wouldn?t it just be a vent? Been a while since I?ve been around one but I thought the filters were either where the boom attaches to the machine or in the back right swing door
 
That would be the breather filter,the machine has both a suction strainer in the tank as well as the main hydraulic filter,some had an element type and others had a spin on,the machine should have its filters serviced at regular intervals,slowing up when it's hot could be the o'rings on the main regulator valve body letting the oil bypass or the pump is getting to show its age,a service man and a pressure test is the way to go.
AJ
 
Getting weak when hot is a dead give away for pump getting weak, just can not pump that thinner oil as fast. There is a return filter in top of tank but think you are wasting time on the filters. Flow meter on the pump will prove it but takes more than some tractor place will need one with volume.
 
The return filter is in the tank. The suction strainer should be under the plate where the tank cap is, and it's nothing but a wire mesh strainer. I've never seen one of them that needed to be cleaned out unless the pump failed, and then it's usually cheaper and easier to just get a new one than to clean out the old one.

That said, it sounds like the pumps are getting weak as others have stated. Unfortunately the only way to check one of those pumps and get an accurate diagnosis is to use a flow meter with the ability to load the system. The ability to load forces the pumps to adjust to the higher pressure, lower flow condition which is what you need to see what's going on.
 
AJ.

I am trying to contact you direct with a question about a Liebherr 932. I noticed you helped another member, CASE450 with the same problem in the past.

The Pilot controls will go dead.
The Electric Safety Solenoid has been by-passed by directly plumbing the hydraulic Gear Pump line to the Pilot Control Line, so the Safety Circuit to the Left Control Arm is a NON-Issue.
Also, I have confirmed there is pressure from the Pilot System Gear Pump.

What I would like to know is, Is there other cut-0ff valves in the pilot system. For example is there an Engine Oil pressure, or Temperature, or Air pressure sensor(s) connected to another valve somewhere? OR what else should i be looking for that would cause the pilot system to loose hydraulic pressure?

Greatly appreciate any help. Thanks
 

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