L150H Fan issue

[Innocent bystander]

L150H 007181 Fan keeps slowing down to 150-190 RPM then machine runs hot.

All brake/accumulator tests pass(unless Im missing something).

Pump 3 runs brakes first then after accumulators charge to cut-off pressure then pressure goes to fan.

At start up brake pressure cut-out pressure is spot on spec at 2250 psi then fan kicks up, once machine gets to operating temp and starts working, brake pressure will go to 2500-2600 Psi and will not cut-out thus never spins up the fan.

Any ideas?

Thanks.

 

[Innocent bystander]

Maybe MA5503 getting hot and crapping out?

 

[funwithfuel]

Check pressure reducing valve setting. Either place a gauge on the accumulator manifold or read the values from the service screen. Observe your cut-in / cut-out pressure. When you're confident you've reached unload, where your fan should be getting the oil, curl your bucket back over relief. Observe the pressure it shows on the display. It should be at least 150 psi or 10 bar greater than cut out pressure.

 

[Innocent bystander]

How do you adjust that? I cant find it in Prosis

 

[funwithfuel]

Since you have prosis, look at central valve under description. There are 3 pressure reducing valves on the block, pilot oil, brake oil and maximum steering pressure. Obviously, your looking for max brake pressure. Usually a half to three quarter of a turn will get you where you wanna be. Never exceed 2400 psi max brake charging

 

[Innocent bystander]

It kicks out at 2250....until it doesnt then will go to 2500-2600 but never kicks out. like it gets stuck.

 

[funwithfuel]

So, are you reading off a gauge on the manifold or the displays pressure sensor?

 

[Innocent bystander]

display

 

[Innocent bystander]

Im thinking MA5503 may be dropping of like the older shift solenoids used to do when the get hot and not diverting pressure back to fan.

 

[funwithfuel]

Yes, I agree. You can check voltage to the coil itself or when oil is supposed to be diverted to the fan, remove the coil and see if it will grab a screwdriver in the center. If it grabs strong, place it back on the stem. If you don't hear a shift in oil, then the stem is probably compromised.

 

[funwithfuel]

There should be a center plunger on the stem where you can manually exercise it by pushing in with a scratch awl or ice pick.

 

[Innocent bystander]

Fixed! MA5503 solenoid valve was sticking. Coil was OK.

Also I had it backwards, coil needs to be energized to charge(divert to accumulators). De-energized to cut-out and send pressure to fan.