Facing a knocking industrial compressor is rarely a simple fix. You have to weigh the cost of a new pump against the value of the rest of the machine. The Quincy BM5120ST QR5120 listed here at USD 2,500.00 forces that exact question: it's a complete industrial reciprocating compressor sold as-is because the pump knocks and needs attention.
Quick Verdict
This is a buy for a buyer with repair capability or a specific need for QR5120 components. The unit is described as having been removed from service after a knocking noise, inspected by a Quincy technician, and test-run again with the knock still present. The technician's recommendation was to replace the pump. Anyone considering this unit should assume the pump needs repair or replacement before the compressor can be put back to work.
Who It Suits
Buyers who can diagnose and rebuild a reciprocating pump, need a complete industrial compressor for a rebuild project, or seek a parts source for a BM5120ST QR5120 package. The seller is explicit: the unit is being sold as-is for repair, rebuild, or parts.
What Stands Out From the Listed Details
The compressor is stored indoors and has not been disassembled or fully diagnosed beyond the technician's initial inspection. The exact internal failure is unknown. That lack of diagnosis is the most important detail: it means the buyer's first task is determining whether the pump can be rebuilt or must be replaced.
Meaningful Trade-offs
Trade-off: you're paying for a compressor with an unknown internal failure. On the positive side, it's a Quincy BM5120ST QR5120, and the unit was inspected by a Quincy technician who retightened the valves and test-ran it; the knock remained. That information is useful because it suggests the issue is not simply loose valves. On the other hand, the exact failure is unknown, and the seller recommends assuming the pump needs repair or replacement.
Bottom Line
If you have the skills and equipment to tackle a reciprocating pump failure, the Quincy BM5120ST QR5120 offers a complete industrial compressor that can become a working unit after pump work. If you're looking for a ready-to-run compressor, this is not that machine.
Product Notes
Quincy BM5120ST QR5120 Industrial Air Compressor - Knocking - Needs Repair
Listed at USD 2,500.00 in For parts or not working condition. The seller notes that the compressor was removed from service after developing a knocking noise, that a Quincy technician inspected the unit and retightened the valves, and that the knock remained. The technician recommended replacing the pump. The seller chose to replace the compressor to minimize production downtime, and the unit has been stored indoors. It has not been disassembled or fully diagnosed, so the exact internal failure is unknown.
