Oiling and inspecting your Evaporative Cooler or Swamp Cooler bearing block bearings can save you major headaches and expense. On most Coolers, oiling the bearings is a very simple job. The majority of residential and small commercial models come with a bronze bearing. There are no moving parts to these bearings as there are with ball bearings. Bronze bearings are made with a sleeve of bronze inside a steel die-cast housing. The blower shaft spins inside the bronze sleeve. These bearings allow for a smooth, low friction motion between the two solid surfaces. The bronze portion of the bearing is generally about 1/8 to 3/16 of an inch thick and is porous for continuous lubrication. You will see an oil cup at the top of the bearing. Open the cup and drop about 5 - 10 drops of lightweight machine oil into the oil tube. This should be done at least once a year for light Cooler use, or multiple times a year for heavy use. Even though bronze bearings are relatively inexpensive they are quite durable. Often times, if oiled regularly and the belt tension is maintained correctly, the bearings will last for the lifetime of your Evaporative Cooler.
Inspect The Bearings
It is very important that you inspect the bronze sleeve pillow bearing block thickness when you oil the bearings. As I mentioned earlier the sleeve of bronze in the bearing is only about 1/8 to 3/16 of an inch thick. The steel blower shaft is constantly spinning within the bronze sleeve. If the steel shaft eventually wears through the bronze sleeve, then you have steel spinning on steel. Steel spinning on steel will make a loud, high pitched noise somewhat similar to the sound of a loose belt squeal. Once again it is very important that you inspect the thickness of the bronze sleeve. When any part of the bronze sleeve has worn to ½ of it's original thickness the bearing should be changed. If you let the bearing get to the point of steel spinning on steel, you have damaged the blower shaft. Once the shaft has been damaged, you will never be able to use a bronze bearing again. The rough shaft will quickly wear through a new bronze bearing. At this point I would recommend installing a more expensive ball bearing with set screws in the inner race. This will attach the inner race of the bearing to the blower shaft and the shaft damage will not cause any future problems. If the ball bearing ever goes out it will never damage the blower shaft.
Changing Cooler Bearings
Unlike most other types of blower units Evaporative Coolers are constantly producing moist air which creates rust on the blower shaft, pulleys, and bearings. This often makes it more difficult to change the bearings. There are two things that I always recommend when changing Cooler bearings. Use a penetrating solvent on any parts that are rusted together. This often happens on the blower pulley and shaft, as well as the inner race of a ball bearing and shaft. Even after using a penetrating solvent I have sometimes had to use a pulley puller to remove the blower pulley. The other recommendation that is very important, always sand the rust off of the blower shaft before pulling the blower pulley or bearing. If you don't sand all the rust off the shaft, you will not only have problems removing the pulley and pillow block bearing bearing, it will also be difficult to slide the new one onto the shaft. You might also be tempted to use a hammer to drive the new bearing into place, which often can damage this bearing. As you can see, a few pieces of sand cloth to sand the rust off of the shaft will make the job much easier and actually save you time in the long run.