98 Monaco N14 Cummins 525 overheating problems

[1doodadd]

Since you have tried Colton Truck Terminal, have you also tried Western Hydrostatics in Riverside Ca. I have personal experience with this company and they KNOW there Stuff. I would call them or take your pump to them and let them know what your experiencing.


https://www.weshyd.com

[mdereyes]

August 26, 2018. Getting close to a solution on the hydraulic cooling fan problem. The coach, at the shop since October of 2017, has been a learning experience. After 4 hydraulic motor repairs, 57+ gallons of AW 46 hydraulic fluid, assorted hoses, fittings, etc., I am close to having the problem. The hydraulic motor has an absolute pressure of 3000 psi; somehow pressure transients exceeded this and blew the primary motor. The previous owner of the coach had modified the system and disconnected the wax valve. So as a new owner, I had to take a course in hydraulics, learn about Monaco's pre-bankruptcy hydraulic design, compare it to what is currently installed, and repair defects in installation and get a working system. I have placed a relief valve/pressure control valve in line to keep the motor pressures at 500 psi. This speed is sufficient for cooling, but will not hit the 3 X current pressure transient limit of 3000 psi. Last go around the relief valve was set for 1000 and the motor front seal gave way. The last time, I had a slower fluid loss and enough pressure to get the coach back to the shop,
without losing all the hydraulic fluid. I love my RV and enjoyed it, for the one trip my wife and I took. It is unfortunate that some manufacturers, don't design their units better, and/or include schematics of each system or sub-system. Aircraft, often priced the same have it because it is required. If we demanded it, the market would make them comply!

[mdereyes]

Thanks to the folks at Colton Truck Terminal, AZ RV Salvage, NW RV Supply and Scott and Joe with Source RV, for helping me with questions. I greatly appreciate them and my fellow IRV 2'ers who also helped. Good to be in company of a great community.

[oldguy70]

On my rig with a 8.3 Cummins the Sundstrand motor is 00895/210 and I googled that #
and came up with a motor. My end cap was leaking and I now have that fixed and now
my motor won't start up until the engine gets up to 1500, th

[oldguy70]

I was typing and all of a sudden it was posted. The # for my Sundstrand is on a plate on
the top. As your engine is bigger you may have a bigger system. I have 2 pumps in the
same case 1 for the fan and one for the steering.

[mdereyes]

Hi. Please notice the first date of my problem. Now it is finally completed. After months of work, 6 blown hydraulic motors, seals, 60+ gallons of hydraulic fluid, 1 hydraulic course, about $4k, and hours and hours of work, my maintainer and I separated systems using the same pump, and dumped the factory pressure control valves. With the help of my hydraulic supplier, we finally got the coach to go 250 miles to home. The main fan motor turned too slowly to cool properly, but a cool night and additional electric fans, let us drive it at 50mph without cooking the engine (235F).
Two lessons learned. One is "economically" efficient design is not the best. Second is an "orphaned" coach has no support. I have re-designed the system to work better and longer than the original. If anyone has problems with the rear (main) hydraulic cooling motor, I would be happy to help with anything I have learned. People urged me to sell the coach, but stubborness, dogged determination and a like of the general coach, kept me working. Monaco made a good coach, despite hydraulic design flaws.

[guardrail53]

Wow, this has been a journey, for sure! Glad you got it fixed! Rail! [emoji266]