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Noises and Leaks and Amps, Oh my!

A well-maintained Vacuum Pump will last many years. But occasionally, issues do arise and your pump might need repair. And sometimes these issues are difficult to decipher without an expert there. But there are some initial steps you can take to troubleshoot a cranky Edwards or Welch vacuum pump. When analyzing pump problems, look for the 4 following things:

  • Noises
  • Leaks
  • Ultimate pressure
  • High amperage draw


Noises can come from things like fans rubbing on fan covers or motor couplings with broken rubber elements. These are considered ‘external’ in nature and can often be remedied without complete disassembly. If no external source of the noise can be found, the unit will need to be disassembled.


There are really only 2 main places a Vacuum Pump can leak oil from, the oil case gasket or the shaft seal. The shaft seal is far more common and usually fails due to oil contamination. Some pumps have an ‘external’ shaft seal which can be changed without complete disassembly while others must be completely torn down to repair. Though rare, oil case gaskets can sometimes begin to leak oil over time. When they do, it is usually an easy Gasket Replacement to repair.

Ultimate Pressure

While most processes can endure some noise, or even an oil leak when pumping pressure begins to climb it is service time! Reasons for a pump being unable to achieve acceptable ultimate vacuum levels can vary, but almost always require the unit to be disassembled to find out.  Prior to disassembly, we look for obvious external problems such as a ballast valve left open, a loose intake connection, or low oil level. When no obvious external problems are found, the pump will need to be disassembled for inspection and rebuilding.

High Amperage Draw

As Vacuum Pumps Wear and/or get large amounts of internal contamination, a larger load is put on the electric motor. This will manifest itself as a higher amperage reading. Occasionally, motors will just wear out and the attached pump will be OK, though this is rare. In our experience, electric motors are far more dependable than the Vacuum Pump they are attached to. High amp-draw is usually a good clue of internal pump problems.