I had the opportunity to purchase a Welch 1397 Vacuum Pump from for $60 on Craig's list. New, this pump would cost almost $7500. It weighs 200 lbs. It is rated to move 17 CFM per minute and pull a nearly perfect vacuum.
I bought it because I wanted to build a vacuum kiln for wood.
I took the pump to Tech Shop and tried to rotate the fly wheel and unfortunately, this thing had seized. I had a choice scrap it for $35 or try to get it to work.
I spent less than $50 to get it working.
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Step 1: Use Leverage to Free the Vanes
This is a real kick'n pump. It uses rotary vanes and oil to create a vacuum.
The vanes were rusted to the walls of the inside cylinder. Using a crowbar and a 2x4 that was cut down to a 2x2, it was possible to get the vanes free and successfully rotate the large flywheel.
Step 2: Does the Pump Suck?? If So, Drain the Old Oil -- Else Full Rebuild
I put my hand over the intake and rotated the flywheel. I felt suction! This pump sucked! That was great news.
The next step was to drain the old oil and see what it does with clean stuff.
This is what the old oil looked liked.
Step 3: Remove the Exhaust and Dump in Fresh Oil
I bought 4 quarts of vacuum pump oil. After removing the exhaust filter, I dumped in a full quart and rotated the flywheel by hand several times.
This is what it looked like draining it the 2nd time I did this.
Step 4: Extend the Oil Drain and Keep Changing the Oil
I got tired of fooling around holding the oil drain pan in mid air and put a "street 90" right angle and a ball valve on the pump.
This made it really easy to change the oil one pint at a time. I would cycle the power for the motor for about 15 seconds each time.
After 5 oil changes, the oil was running clear!
Step 5: Change the Rotted Belts
I bought two belts at Grainger and figured out how to loosen them. After I put them on, and tightened them this thing runs like a charm.
Step 6: Test the Vacuum
I had an old vacuum gauge lying around and hooked it up to the intake manifold.
I live at 1000 above sea level. 29 inches of mercury is a perfect vacuum at that altitude. This gauge reads almost that.
Tech Shop helped me pull this off -- I made this work at Tech Shop!!!