TJ 325 has jumpy oil pressure

[Dairyguy]

My NH TJ-325 4whl drive has unsteady engine oil pressure reading. It constantly fluctuates 2-3 lbs., but sometimes will lose 25-35 lbs suddenly, then stall. We checked the pressure with an external gauge, and it is steady. Only 3500 hrs, and runs fine. We changed the sender. Thanks for ideas.

 

[Soundguy]

so. on a mechanical gauge, pressure stays steady, does not jump and does not loose dozens of psi?

but it does with a sender and electric gauge?

if you have repalced the sender and no jooy.. I'd try to trace out the wireing.. may have a fualt in the harness. does this machine have a low oil pressure shutdown?

( I'm unfamiliar with that exact machine..e tc. )

one thing you can do is run an external bypass on the wires from sender to gauge to check to see if it makes a difference.. also.. run a mechanical and sender in tandem with some fitting maginc.. check often..e tc.

post back

soundguy

 

[Dairyguy]

Yea, it has an electronic control box on the engine, and an auto-shut-off safety feature. There has to be a bad connection, or a bad board. We will need the tractor soon, and there is no service til tuesday. There is no gauge, just a digital readout. Yhanks

 

[Jerry/MT]

My NH TJ-325 4whl drive has unsteady engine oil pressure reading. It constantly fluctuates 2-3 lbs., but sometimes will lose 25-35 lbs suddenly, then stall. We checked the pressure with an external gauge, and it is steady. Only 3500 hrs, and runs fine. We changed the sender. Thanks for ideas.

If the mechanical gauge shows that the pressure is steady, but the sendingunit/indicator shows fluctuations them either there is a loose ground wire or the circuit voltage is fluctuating causng the indicator to read incorrectly. Check the ground connections(both chasis and local) and look for loose wires, etc. If they are good, then the voltage limiter or card probabaly is faulty.

 

[BeeferMan]

Just a guess here based on the two symptoms (loss of pressure on the electrical gauge and stalling), but it may be that you have a short which is causing the pressure signal to drop and also dropping the voltage to the fuel shutoff?