A customer has a PC20 (-1 I think), that after the oil gets hot, it won't untrack itself. Best I can tell, it has 2 gear pumps, one for dig and the other for travel. I am going to get a fitting to port my gauge into it but with nothing more than an operators manual, I can only assume a normal pressure of low 2000's PSI. I suspect a worn out pump. Regarding the grey market factor, the owner after past experience and I are worried that the replacement cost of a pump will be a machine killer. Any experience on acquiring major parts for these little units?
This is just a guess im suspecting with older macbines, How old is the oil? If the original oil spec is similar to a 5w30 and it breaks down after time it's essentially like a 5 when warm. Maybe too thin to properly pressurise, warm oil might thin enough to leak by the pump or motor
I believe you are right about the 2 pumps being gear pumps. Factory pressure might be a little more than 2,000 PSI. How old is the machine and how many hours are on the clock? If the shaft bushings haven't gone out in the pump you might be able to install new end plates and seals. The kicker on those types of machines is if the gears have started eating into the case. At that point they are junk and will need to be replaced. It isn't hard to tear one of those pumps down. Usually harder to get it out of the machine.
Looking at them, they are what I consider a throw away pump as once they are worn, there isn't any fixing them unlike a sectionalized Webster. The owner called yesterday and said he was told it might be stuck in high speed travel and if so, maybe getting it shifted down would give it enough torque to keep working a while longer. You're right on getting the pumps out, they are buried! He told me he had recently changed the oil to an AW 46 grade so viscosity shouldn't be an issue. If it is, I might recommend he put a bottle of Lucas in it or change to AW 64 or gear oil ! Thanks for the responses. I am making a test fitting for it tonight and will check pressures tomorrow.
Kinda found the problem. I ported into the main valve and got over 3200 psi at startup. Owner said the engine had been overhauled and the two speed didn't work after that. I played around with it and on a restart, had no pilot functions so I traced hoses down to a 2 solenoid block which was disconnected (presumably by whoever overhauled it). I removed the block and made a longer plunger rods to block both valves inward and upon reinstall, all functions came back along with slower travel speed and more power to tracks but with one side weak pulling. It had defaulted to high speed with little tractive effort. I left with the owner happy so I guess I accomplished what he wanted.