Hydraulic Cooling Fan Motors

Some RVs have hydraulic cooling fans. The good news is that these fans operate from the hydraulic system of the RV and do not require a fan belt or other source of power. The bad news is that they operate from the hydraulic system of the RV. My fans motors began leaking so I ordered the seal kits from Monaco directly. You will need the motor number and other identification information to order seal kits. Order before you start the job, it takes a while for the seals to arrive after the order and they are probably not available locally. (My motors are Sauer-Danfoss.)

More bad news, the seal kits were $60+ each (Rebuilt fan motors were over $300 for the pair. You don’t want to know that new motors were (over $600/pair.) However, the task of replacing the seals is very easy but a little messy. The ugly part of the seal replacement is that the multiple hydraulic lines must be disconnected. You will lose a large amount of transmission fluid from the reservoir unless you have plugs that you can insert into the hydraulic hose fittings. If you don’t have plugs, you are looking at about 4 gallons of fluid replacement. I purchased several sizes of male and female hose fitting plugs for the job. I blocked off the lines at end points on either side of the feed and return lines.

Motor removal isn’t too bad. I had to remove several support brackets then four bolts holding each fan motor in place on the shroud. The motors are a little on the heavy side, with the brackets in place, but they are easy enough to manage.

Once the motors are removed, remove the fan blades and clean them. I used a puller to pull the blade off the shaft. Be careful with the blades. Mine are plastic and can easily break if dropped or abused.

The seal kit contains two valve seals and a shaft seal. Remove the back from the motor and the valve seals are visible. Note that two seals are imbedded in the grooves for the backing plate. Remember which ones are on top and which ones are under them. They are two different colors so this should be easy to remember. Remove the old seals, replace the new seals. Make sure that the valve seals are pushed into the grooves. They seem to snap in place as you push them into the grooves. The shaft seal is simple and straight forward. Pull the housing off the shaft, remove the old seal and install the new.

Replace the housing. Replace the fan blade, reinstall the motor, connect the hydraulic lines, add fluid and check for leaks. You are good for another 6 or 7 years.

My replacement took about 6 hours total. Considering the RV service cost at about $100/hr, I feel my time was well spent. The job is simple, but a little messy. I can take messy at that price.


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