Can I rebuild the hydraulic pump for a Mitsubishi MT 372 D/Satoh 370 Beaver

[Alesandro]

"Assuming your pump is bad (and it prob is not)"

This is not a response because I was offended, but what does that statement mean? I ask because I did very little trouble shooting only because I don't know how to test or what to test. Here is a question; if the return line from my controller valve back to the reservoir had a pin hole in it, would it suck in air not in big bubbles but small atomized air that would aerate my hyrdraulic fluid and make it perform less?

Just a thought and thanks for all the help!

 

[dfkrug]

This is not a response because I was offended, but what does that statement mean? I ask because I did very little trouble shooting only because I don't know how to test or what to test. Here is a question; if the return line from my controller valve back to the reservoir had a pin hole in it, would it suck in air not in big bubbles but small atomized air that would aerate my hyrdraulic fluid and make it perform less?

Just a thought and thanks for all the help!

I think you may have found the problem, noted above. The piece that fell from your valve.

A hole in the return line (TANK) would be under positive pressure (low), so would not suck in air.
It would leak oil.

 

[Alesandro]

I think you may have found the problem, noted above. The piece that fell from your valve.

That piece was actually needed, it slowed down the speed of my bucket as it was lowered so it was more controlled.

 

[Alesandro]

View attachment 504601View attachment 504602
If your pump looks like this one I'd buy a new one off Ebay I think I paid around $280. The shaft broke on mine and dealer wanted $1,200.

How easy or hard was it to change your pump? My replacement will be arriving today and was wondering what is involved to exchange the pumps.

Thanks for the assistance.

 

[Alesandro]

I got the used pump today and it's a little dirty on the outside (expected), no biggie. Can I completely open the pump and inspect it, or will I need to buy new seals once I crack it? I would like to look inside of it before installing it.

 

[Ilikeurtractor]

You could open it without needing to replace seals but I'd recommend not. The "little dirty on the outside" can wind up being a little dirty on the inside and precision mechanical components do not bode well with even small amounts of dirt being introduced, especially hydraulic pumps and motors which dirt is the #1 enemy of. The risk to reward wouldn't be there in my opinion. Try it out as-is and see if anything has changed.

 

[Billrog]

It is not very difficult to install without a pic. of your machine I'm not able to give any kind of instructions. I would make sure your machine is clean where your taking the pump off remove the lines and put the new pump in reversing the process. You may have to unplug some wiring to get it out of the rd.? And you may have to remove a metal return line that runs under the tractor. I'm only guessing but sure you'll figure it out. Like recommended I would not pull the pump apart because there's a real good chance you would know what you were looking at to see if it works or not.

 

[Alesandro]

Ok guys did some testing with a pressure gauge and the following is what I got;

I put the pressure gauge right before the inlet of the control valve assembly, started up the tractor and let it warm up for about 5 mins. I get "0" when I don't pull any levers, when I pull the bucket up lever I get around 1800psi and the same for bucket tilt. I then started to move some dirt around and maybe 10mins into the ordeal my bucket up starts to slow down. The pressure needs to rise slowly before I can get the bucket to come up. After a while the bucket will not come up very fast and needs to build pressure before it moves. After a while the empty bucket will not rise and the gauge won't go any higher than 850-900psi. The whole time during testing the bucket tilt didn't seem to have a problem and when I reached the extends of the bucket tilt the pressure shot really fast to about 1800psi and squealed.

Please keep in mind I did change the control valves a couple days ago and I still had the issue.

Does this tell me that there is something wrong with the pump, the lines for the bucket lift after the control valve, or maybe my pressure relief valve.

 

[Alesandro]

What do you think of this hypothesis;

I still think it may be the pump. Even though it can still reach the 1800psi mark with my bucket tilt, that uses (1) hydraulic cylinder, it needs to build up pressure on the bucket lift as there are (2) hydraulic cylinders, but, my flow rate has decreased. So the pump can still hit 1800psi but at a much slower rate than when cold.

Just so everyone is aware, apparently the hydraulic shops around here are super busy and it would take about 2 weeks to get the pump tested, as that would be the best way to test for flow rate.

Just a guess let me know what you think.

 

[Ilikeurtractor]

... After a while the empty bucket will not rise and the gauge won't go any higher than 850-900psi. The whole time during testing the bucket tilt didn't seem to have a problem and when I reached the extends of the bucket tilt the pressure shot really fast to about 1800psi and squealed...

That sounds to me like one or both of the lift cylinders are by-passing the pistons which becomes more pronounced as the oil heats up and viscosity goes down. You say you "fixed one of the cylinders" on the loader - which one? The squealing you hear is the relief valve lifting either on the tractor or the loader control valve. If you lift the bucket up as high as it goes, how long does it take for it to fall on its own back down (if it does)?