2005 LS185b - Charge Pressure Warning Light Illuminated

[eeastment]

2005 New Holland LS185b, high-flow, single-speed, 2193 hours on the meter.

I just drained and replaced/refilled the hydraulic oil and replaced a hydraulic hose, the 1” pressure line that goes to the main oil cooler. The old hose was externally damaged but did not burst or leak. I caught before it broke.

After replacing the hose and changing hydraulic fluid and filter, I ran the skid for about 10 minutes. It drove fine and all hydraulics operated normally.

The next day I operated the machine again, but, about 20 minutes after startup, the red “charge pressure warning lamp” (see photo) began flashing with an accompanying beeper. Varying RPM did not get the light to go out. Machine performance was normal with the light still flashing. No degraded performance was observed.

Questions:
1.) has anyone else had this problem right after a hydraulic fluid change? Was there a reason/solution?
2.) has anyone had this problem any other time? What was the problem/solution.
3.) anyone have a sensor/pressure switch go bad?
4.) is it possible that an air bubble caused this?

2193 hrs on the clock, I’ve owned it since 1308 hours. I keep up on maintenance, fluids, cleaning, and care.

Manual says to check charge pressure on the pump (360 psi). Gauge set on order to do this.

Any advice or experience to share would be greatly appreciated!

Thanks in advance.

 

[eeastment]

OK, I had time to dig into it and here are my solution and thoughts on why the alarm came in…

I purchased a Vevor brand hydraulic pressure monitoring kit for $135 which has five gauges for pressures up to 10kpsi. To test the charge pump I used the 1500 psi unit. The kit also included a plethora of fittings to T-into the charge pump pressure port. Warning: the fittings, being Chinese made and horribly mass produced, required cleaning and a drill bit to deburr the drilled passages. There were burrs that could possibly come off and ruin the machine. I knew this could be the case and thoroughly checked them over before connecting it.

per the manual, the pressure port is under the seat on top of the pump. It has a line plumbed into it. I used a 3/8” T-fitting that came with the kit and connected the 1500 psi gauge.

Step 1 was to warm it up (fluid to 125F) and check pressure in neutral (not moving).

Step 2 was to adjust pressure, if necessary, by adding shims to the pressure relief valve.

Step 3 was unclear. It said to raise machine into the air and check charge pump pressure when giving it one stick in one direction (4 total checks). The manual assumes the parking brake is engaged and thus by moving the stick you’re applying hydraulic force to the motor with brakes applied and no wheel motion would occur, just dead-head pressure to check for fluid leaking by in the pump & motor. The problem is, with parking brake engaged, in normal operation mode, control stick motion does not apply pressure to motors. I assume there is some solenoid the prevents pressure to apply to the motors with parking brake engaged. I have not tried this step in the maintenance mode, perhaps I’ll do that next. Anyway…

Pressure at startup was just over 300 psi (no alarm), once warmed up until fluid was at least 125F (per manual) the pressure dropped to near 275psi and the alarm came in. The next step in the manual was to remove inspect and add shims to the pressure relief valve (easy to access with seat up) to increase the pressure to the minimum spec of 360 psi when fluid was warm. I added 0.080” with of shims to reach the specified pressure. Machine was used for several hours and never had the alarm again.

Why did this happen?
My thoughts go like this… the alarm came in for the first time I got it warm after changing the hydraulic fluid and filter. I think the old fluid was a bit more thick (viscous) than the new stuff, even thought it’s still 10W-30, and the pump probably had some wear over the last 863 hours. That wear may have brought the pressure down a bit but the older thicker fluid kept pressure just above the alarm limit. The new thinner fluid (thinner because it’s new, not degraded) was just enough to bring in the alarm once the machine warmed up to operating temp. The machine has never had degradation in performance.

I have a few more tests to make (pressure drop checks with pressure to the motors and brake applied). But for now everything seems normal.

Has anyone performed these tests/checks before? Any experience or explanation would be helpful.

 

[eeastment]

Sorry, duplicate entry!