Pressure test isn’t going to tell you the difference between suction line problems, plugged filters, bad pump and so on. You are making this way more complicated than it needs to be in order to rule out some of the more basic reasons that can cause hydraulic problems.
Lets duspense with the special tools idea. A hydraulic pressure gauge is no more expensive or special than a multimeter. If you own a tractor, especislly one with a back hoe on it, and expect to diagnose and service the hydraulics its an essential and very affordable tool. I have had several in my toolbox for decades and they have uses outside of tractors.
Moving on to priblem dolving a good pressure test result at the hydraulic outlet rules out all of those potential suction side problems in one fell swoop.. Likewise a bad one positively confirms there is a supply side problem but does not tell you what. Thats just orderly diagnostic process 101.
A hydraulic pressure test is no different than using a voltmeter or ammeter to probe a defective electrical circuit looking for loss of voltage or current. It gives you both quantitative and qualitative results.
I certainly have no objection to your proposed visual inspection looking for obvious problems. Thats perfectly reasonable. Blindly taking things apart on a hope you might find a problem not so much.
What are you going to do if all that suction side inspection comes up empty? Maybe then you would think a pressure test is in order because you still can't rule out the pump or the relief valve and still dont know if the problem is there or in something upstream?
Problem isolation does not complicate things it simplifies them. Its fast, easy and definitive and helps narrow down the things and places to look at. Its how I have diagnosed everything from cars and trucks in my personal life to computer software, hardware, and network failures in my professional life. Its a logical orderly diagnostic approach that has served me well and helped me earn a very comfortable living.
Dan
