Hello everyone I have a weird situation where my charge pressure is reading 400psi at idle and when I go into high RPM it shoots up to 900+psi. I tried turning it down at idle and it does go down below 400 at idle. To get it around 450psi at high idle when it’s at low idle it’s around 200psi. Brand new charge pump.
At 400psi idle the machine will not move. At 200psi idle the machine will operate normally. How is that possible?
Another weird note is I have 300psi at the fan SOS port which is the outlet side of the fan to the filter housing. I replaced the filter again but still nothing at the hystat pump. I’m going to take the 90 off at the charge pressure test port I threaded a gauge on without the test port quick connect and still nothing is the check valve in the 90 or in the testing adapter?
Charge pressure specs are based on a specific rpm. Do you know what that rpm is and what the pressure reads at that speed?
1180RPM pressure at tap on hystat is 180psi sos on fan is 300, brand new filter cut the old one no debris. At 2530 rpm charge pressure at hystat is 220psi and 350 at sos port on the fan.
I’m getting a new pressure gauge tonight for a more specific pressure reading. I thought maybe the filters I got were the problem given they aren’t caterpillar filters because caterpillar didn’t have them. I took it out and ran it briefly with the same results. If there was a significant leak in one of the hystat pumps I wouldn’t think I would have such a differential in pressure. Is there anything inside of the filter housing that could cause this issue?
With out knowing all the ins and outs of this it's possible you have an internal leak in the pilot system and not necessarily anything to do with the filters. A broken 0ring in the valuing could also be the cause. Testing is going to find it.
I just got done running a line directly from the charge pump to the hystat and it is showing the same thing. I’m thinking internal leak given there is nothing else in the circuit besides the brake solenoid which is new. I don’t know how it could have just happened just suddenly. Usually they wear out pretty slow. Machine still moves and functions fine just charge pressure is really low. I’ll have to get the attachments out of the shop and then tear it down and find the problem. I’m assuming it’s a stuck flushing valve or some seal to the case is bad.
I capped the line to the two speed and implement lockout valve block so I know it’s not a valving issue on that side.
For those people without the benefit of a crystal ball how about a make, model, and Serial Number.? At least that would enable specifications & test procedures to be looked up instead of throwing numbers around willy-nilly.
Sorry Nige. It’s a 277D FMT00336 MTL. I have the procedures and testing
These ones.? I'm assuming that you are talking about the hystat system.
Yes I have those
I’m so sorry you guys I was just having a rough day and not using my head. I have a bad gauge. I decided to hook up my old fluid filled gauge and check all is well my nice digital gauge must have just decided it was done reading. I took them into a hydraulic shop on a bench and it was reading weird pressures at 1000psi it was reading about half of what it was supposed to. At 1500 it was reading 3000. Thank you all for the replies I wouldn’t get anywhere with my equipment without these forums.