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Topic: 2010 Nimbus Hydraulic fan control?  (Read 456 times) previous topic - next topic

2010 Nimbus Hydraulic fan control?

We lost hydraulic cooling fans last night coming through Chattanooga TN, and I cannot find any control solenoid following the hydraulic lines off the back of the fan motors to the tank.  I'm not very familiar with the system since I don't think it's controlled pneumatically like I've seen before.  Is there a way to bypass the control to run at 100% to get me home or is there an way to diagnose the main hydraulic pump to see if that has failed?  Or can you educate me on how this system controls fan speed?

2010 Nimbus, ISM 500/Allison 4000

Lavon

Re: 2010 Nimbus Hydraulic fan control?

Reply #1 –
Any signs of massive fluid loss around the engine or rear of coach?  Like if a hydraulic hose blew?

Should we assume that you checked the hydraulic fluid reservoir (tank) and it was full?

Sudden total failure of belt driven hydraulic pump is rare - they usually die a slow death.

Is your hydraulic pump belt driven, or gear driven?

Re: 2010 Nimbus Hydraulic fan control?

Reply #2 –
When I blew a hydraulic line there was no mess and it was hard to find. As Chuck said
first check your hydraulic reservoir.

Re: 2010 Nimbus Hydraulic fan control?

Reply #3 –
My 2000 U320 is probably different but when my fan controller stopped working properly, failed, a call to FOT told me to unplug the electrical connector at the fan controller. On my model year this put caused the fans to run at full speed all the time with engine running. YMMV for a 2010

Might be worth a try. You can always just plug it back in.

Good luck,
Bob

Re: 2010 Nimbus Hydraulic fan control?

Reply #4 –
No hydraulic leaks, fluid level is good.  I'm thinking it's the main hydraulic pump because after 6hrs on the road when we pulled over because water temp was creeping up, the main hydraulic line off the pto driven pump on the side of the Allison was not hot like it's been pumping fluid.

Re: 2010 Nimbus Hydraulic fan control?

Reply #5 –
No first hand experience with your system, but there were a number of PTO driven hydraulic pumps that were not lubricated and "ate" the splines of the pump so it was not turning.

Hydraulic pump Maintance?

Greasable PTO

There are any number of posts on the PTO-driven pumps (if that is what you have).  Just put pto in the search box at the upper right of this page.

Re: 2010 Nimbus Hydraulic fan control?

Reply #6 –
Quote from: Lamiller –
No hydraulic leaks, fluid level is good.  I'm thinking it's the main hydraulic pump because after 6hrs on the road when we pulled over because water temp was creeping up, the main hydraulic line off the pto driven pump on the side of the Allison was not hot like it's been pumping fluid.
I wonder if your year coach uses it for power steering like ours?
 

Re: 2010 Nimbus Hydraulic fan control?

Reply #7 –
This sounds like what happened to Brad M. On lI10 when his coach broke down  I believe his coach is a 2010 also