Rotary Pump Replacement

Okay so here we are, another month and another wonderful espresso machine repair. This time we are going to take a look at one of my favorite jobs, replacing a rotary vane pump.

The pump is the device that builds pressure at the group, a very important part of espresso extraction. Heck, if it were not for the rotary vane pump, we would all still be pulling levers. I for one, really like pump type machines.

I thought it would be cool to do this really technical type of article and get all wordy and scientific, but is that really what you want? Nah, I didn't think so. Okay so here's the deal, sometimes these pumps go bad. Why? Heck, I don't know, it seems there are a number of reasons. Let's start with a lack of water. These units will be damaged quite easily if they lack water flowing through them. Another cause apparently is the miss alignment of the pump to the motor. Heat can also be a potential cause of failure.

Symptoms of a damaged pump include poor water flow or low pressure at the group. High pressure created at the group, and an awful screaming sound created by the one way valves, as they try to deal with the high pressure. A bouncy pump pressure gauge without adjustability, is also a tell tale sign that the pump is in need of replacement. I'm sure there are other symptoms, they simply are eluding me at this point. The bottom line is, they fail and when they do, you replace them. Simple stuff.

The model of machine I'm showing in this article has an internal pump motor. You will note in the photos that this motor has an external copper tube wound around the body. This is a water cooled pump. If your machine does not look like this, do not freak out, it is simply this manufacturers style of internal pump motor. The basic size and shape is what is found in most commercial type machines. The pump that we are replacing is a rotary vane pump. These are manufacturered by a number of firms including but not limited to, Procon, Fluid O Tech, Hydroflow and others. They all function the same and create the same results, pressure at the group.

 

Here we have the pump motor with the pump removed. Note the slot in the drive shaft. Inspect this area for abnormal wear, this can be a cause of pump failure.

In this picture we have the pump removed from the motor in preperation of replacement. You can clearly see the copper tubes wraped around this motor for water cooling of the motor.

Bright and shiny. The new pump ready to install. This is a ring clamp mounted pump. The ring clamp is the silver part located at the rear of the pump.

The first part of this important repair is to find the pump and pump motor. The second part is now that you have found the pump and have decided you are willing to take on this task, TURN THE POWER OFF. Some manufacturers place the pump externally and some internally. You will need to decide which one you have. If you look in your machine and see a large silver motor with a brass pump head attached, you have an internal pump. If on the other hand, you look inside your machine and see nothing that looks like a pump as described above, look under the counter. Hopefully with any luck you will find a motor and pump.

Now that you have found the pump, let's start the removal process. This involves removing the water lines attached to the pump. Make sure that you TURN OFF THE WATER to the machine before you do this part of the procedure. Next remove the ring type clamp surrounding the area where the pump head and motor mate. Some machines use a flange mount system and this requires loosening two to three nuts and bolts then turning the pump a quarter turn. The machine depicted uses the ring clamp.

Once the pump is out, remove the fittings as you will need to place these into the replacement pump. Make sure that you use a thread sealer or Teflon tape when reinstalling the fittings. Now that you have the fittings in place reverse the removal process. Replace the water lines and reinstall the pump to the motor making sure the two pieces are mated together firmly and tighten the ring clamp.

This image shows the old pump with the fittings removed. These can be a bit of a struggle, so you may want to simply use new ones. Make sure you use thread sealer.

Here is the new pump with the fittings and water lines installed. Note the directional arrows showing water in and out and the rotation of the pump.

Almost done. Make sure that the pump is mated to the motor firmly and tighten the ring clamp. Note the slotted screw head on the pump. This is the adjustment screw.

At this point you are ready to restore water pressure and turn on the power.

After you have replaced a pump, it is critical that you set the pressure. This involves activating the group and adjusting the pump while the motor is running. The adjustment screw is located on the side of the pump and usually requires the assistance of a straight blade screw driver. As you make your adjustment, you need to watch the pump pressure gauge on the machine and set it to the machine manufacturers specifications, typically 9 bar. Never adjust the pump higher than 10 bar as this will damage the pump.

You have now seen and heard the ins and outs of one of my favorite repairs. If you have a particular repair that you would like to see reviewed, let me know. Until next time.