Aux. Hydraulics on Cat 315BL

[D6c10K]

How difficult, and expensive, would it be to change the aux. hydraulics on a 315BL from 1-way hydraulics to a 2-way hydraulics?
It would require changing the valve setup and controls but its it a matter of adding another valve body or is it more involved?
I would expect buying the parts from Cat would be very expensive but is there a chance of finding parts on the used market?
I'm looking for a machine that I can put a thumb on but finding one that already has a thumb, or one with 2-way hyd. is turning out to be difficult.

 

[DGODGR]

That would depend upon what attachment you want to run on the machine. This would be mostly due to flow requirements (supply and return). Simply putting some fittings and a valve somewhere on the return line is possible as long as you already have the required hose sizes. Sometimes one must route through a case drain filter (may also have to be added to the machine). The valve (even though it will not be sandwiched into the main valve body of the machine) will be the most expensive part. Big hoses (we are probably talking about -16 size for this machine) get expensive as well. Especially if you need the hard piping for the boom and dipper.
In essence (again, assuming that your hoses are big enough for the intended attachment), all you are doing is diverting the return line oil back to tank without going through the valve body of the machine. This is the over simplified version. The mono-directional circuit is intended to reduce flow restriction (and the subsequent heat build up associated with it) the happens when the return oil goes through the valve body.
I would recommend consulting a company such as HKX (or another aftermarket hydraulics company) as they can custom build you what you need based on serial number from your Cat hoe.
I put an aftermarket kit on my 315CL and it cost me around $8k (6 years ago). My system is probably much more complicated than what you propose (because I also need to get the machine to 2-pump flow to the attachment circuit) so I would imagine that my kit would be substantially more expensive than what you propose for yours.
EDIT:
I just re-read your post and see that you want to go the other way (adding bi-directional capability to a mono-directional equipped machine). If the main valve body has a bi-directional capable valve for the aux. circuit (and the return side of the valve is just capped off), it would be similar to what I have posted above. Again, I would suggest contacting an outfit like HKX and provide them with your serial number. They can tell you what you need from there...if your machine is still as it was from the factory.
You could also post your serial number here (always recommended) and a member could possible search SIS (if the machine is a ACT-which it is in this case) to see how your machine was equipped when it left the factory.

 

[D6c10K]

That would depend upon what attachment you want to run on the machine. This would be mostly due to flow requirements (supply and return). Simply putting some fittings and a valve somewhere on the return line is possible as long as you already have the required hose sizes. Sometimes one must route through a case drain filter (may also have to be added to the machine). The valve (even though it will not be sandwiched into the main valve body of the machine) will be the most expensive part. Big hoses (we are probably talking about -16 size for this machine) get expensive as well. Especially if you need the hard piping for the boom and dipper.
In essence (again, assuming that your hoses are big enough for the intended attachment), all you are doing is diverting the return line oil back to tank without going through the valve body of the machine. This is the over simplified version. The mono-directional circuit is intended to reduce flow restriction (and the subsequent heat build up associated with it) the happens when the return oil goes through the valve body.
I would recommend consulting a company such as HKX (or another aftermarket hydraulics company) as they can custom build you what you need based on serial number from your Cat hoe.
I put an aftermarket kit on my 315CL and it cost me around $8k (6 years ago). My system is probably much more complicated than what you propose (because I also need to get the machine to 2-pump flow to the attachment circuit) so I would imagine that my kit would be substantially more expensive than what you propose for yours.
EDIT:
I just re-read your post and see that you want to go the other way (adding bi-directional capability to a mono-directional equipped machine). If the main valve body has a bi-directional capable valve for the aux. circuit (and the return side of the valve is just capped off), it would be similar to what I have posted above. Again, I would suggest contacting an outfit like HKX and provide them with your serial number. They can tell you what you need from there...if your machine is still as it was from the factory.
You could also post your serial number here (always recommended) and a member could possible search SIS (if the machine is a ACT-which it is in this case) to see how your machine was equipped when it left the factory.

I contacted Cat with the s/n and found that it came without aux. hydraulics from the factory so it's been added later. In the service records there were notes that they were wanting to add a hydraulic hammer so that's probably why it has 1-way hydraulics.
I'm not familiar with HKX but will see what they can tell me. There are a number of dismantled machines listed online. If I got lucky there might be valving and controls in one of those that could be bought.
This is a machine that coming up for auction so I'm just trying to get as much info as I can so if I buy it I won't have a big surprise with added cost. My other option would be to just add a fixed thumb, or use it without one.

 

[DGODGR]

Finding a machine that is already equipped the way you want it is always a better value than trying to retro fit attachments to a used machine.