How to Rebuild a JB Industries Vacuum Pump | Mechanical Pros - Vacuum Pump Maintenance 

On my JB DV-142 5cfm pump, the cartridge itself is held together by two allen screws so when I removed the 4 hex bolts, the cartridge stayed together. Another youtuber showed how he rebuilt the cartridge on his smaller JB pump. He had to hone the surfaces flat, and reversed one of the plates which was badly scored. When he reassembled the cartridge, he used two pins or drillbits that were snug fit in the 4 holes to align all the segments of the cartridge, tightened those two allen bolts down, then removed the pins and bolted the cartridge back in place. The two allen bolts go through the cartridge from the opposite side from the 4 hex bolts so you may not see those at first. I'm taking mine apart right now, so far mine looks pretty good inside, though it would only draw down to 120 microns when I started, after changing the oil 4 times with warmups between each change. Motor couple exploded after the 4th change, and had to wait for Amazon to send me a new coupler. Easy install. Specifications say it should go down to 15 microns on the DV-142-N version (newer than my DV-142). I'll be happy with 50 microns, but can live with under 120, as I am not a paid professional HVAC technician. I got my schooling in the Navy years ago, back when R-12 and R-22 were king! Prett rusty now though!

I got to step 1 of the process and found that the coupling was shredded with little bits of rubber everywhere. That's why it's not pulling vacuum. I was able to turn the shaft by hand easily though. You can call JB industries directly for parts that fit your specific pump. They'll need your serial number and model number, but I'd recommend talking to someone, since some of the parts on their website have been superseded by newer part numbers.

Thank you very much for a very clear explanation. But where can we buy parts such as O- ring

I want to know the order of stacking the reeds in the reed valve... this doesn't show that.

Always change your oil after every job. Never leave oil containing water in your pump to rust it!

What is the part number for that rebuild kit. Our parts guy at Johnstone Supply has not found any kit that has o-rings any shaft seal. The kits they sold us have the drain, coupling, 4 rubber feet, & the sight glass.

So my big question is. Should the cartridge be able to turn? I try to turn it with hand and it’s firmly stuck. That’s the part sticking out off the cartridge that goes into the green part that fit into the motor. Once again the motor turns freely with hand but the other part will not move.

What size are the two screws that hold the feet?

HOW DO YOU REBUILD THE CARTRIDGE?

Did I miss the part where you put the oil in?

Can you please elaborate a bit better on how to prolong the life of the pump. You mentioned something along the line of what not to do on startup and shutdown, but I am not 100% clear on that. E.g. when vacuuming a car AC system, what is the proper procedure for starting it up and shutting it down?

I have a 7CFM JB and it won’t start period. In this case should I look into the motor or is there anything else I should consider?

Not so much a rebuild as a simple cartridge replacement

I think first I would empty the oil.

If not rebuild the vanes in the pump waist time you did nothing to rebuild the pump side.

Have a link for a rebuild kit on that 10 cfm?