QUESTION:
I installed a rebuild kit in my vacuum pump and everything worked great for a week. Now when I start the pump, it doesn't build up the vacuum it should. I've got a sick pump. What should I do to get it working properly?
Mark Garrett
Chicago, Ill.
ANSWER:
I am going to assume the vanes and gaskets were installed properly, so we'll rule that out as the problem. The best way to bring your pump back to good health is to diagnose several potential problems, one by one.
First, turn on the pump and check for sounds that indicate the hose has holes in it. This could be one cause of the problem. If needed, replace the leaking hoses. If not, move on to the next step, which is to make sure all hose connections to the tank are secure. Again, any leaking vacuum will reduce the efficiency of your pump.
Follow through, checking your ball valves or knife gate valves to make sure they are sealing properly. If the valves sustained damage and leaks are found, replace the valves. Now we've checked the hoses and the valves.
If you haven't found the source of the problem, it's time to check the primary and the secondary moisture trap to ensure a free flow of air through each. To check the primary, remove the lid and make sure the stainless steel ball is loose and moving freely in the cage. It is possible that it got stuck to the opening when you were taking on waste. This would have a dramatic impact on vacuum pump performance. Same thing for the secondary; remove the band around the two halves and make sure the ball is free and able to move about.
COLLAPSING HOSES
If all appears well so far, then let's check the connecting hoses between the primary and the secondary and from the secondary to the vacuum pump. These hoses may have collapsed due to age or the connections are not properly secured. They may have been bumped somehow and the fittings aren't sealing properly.
If you've checked all these spots and you know the new vanes, bearings and gaskets have been installed correctly in the pump, it's time to backtrack for a moment. Sometimes, the obvious is overlooked. I have a saying at my house: If it doesn't work, plug it in.
Return to the vacuum suction hose. Disconnect it from the tank and run the pump. If the vacuum rises to its normal operating speed, the answer is simple. There is no leak in the hose, because you've checked it earlier, but perhaps a rag or something has made its way in and is creating a minor airflow blockage. Or for that matter, it might be a major blockage.
Checking the vacuum tank without the hose quickly tells you if the problem is a blocked hose. If it is, then locate what's blocking the airflow and figure out how to remove it, or simply replace the vacuum hose. The blockage may be in a spot where you can't get to it without cutting the hose open. You can still save shortened hose pieces for other purposes, such as bridging the primary and secondary.
A SIDE NOTE
The best way to tell if your system is operating as expected is to read the pressure/vacuum gauge. It should be located within easy eyesight as you are starting the pump. If your pump operates normally at 19 or 20 inches of mercury Hg, and then one day drops to 14 or 15 inches of mercury, something is wrong. It only takes a second to view the gauge and this is the quickest way to confirm something is wrong with your system. The gauge is there for a reason. Use it.
