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Quincy 5120 compressor losing oil out the intake

tomjelly

Stainless
Joined
Aug 26, 2007
Location
GA
Ended up with a 25HP quincy 5120 recip air compressor. Was a backup for a screw compressor. There was some oil on the outside of the machine, and one of the intake air filters was soaked with oil. The intake is routed on the cylinder in question so the filter is almost upside down at an angle so any oil expelled would not be sucked back in when it starts and drips out of the filter outer cover when it formed a little pool in there of about 2 tablespoons. The other filter is also inverted and not wet. Just wondering if what I'm seeing is because of that and it would go away with the filter vertical and above the cylinder head (all the photos I've seen of these have the filters on stacks above the head) or if there might be an issue that would warrant further investigation. I was not able get any info and have not run it yet.
 
I would run it a little while and verify the source and volume of the oil. Could be a bad intake valve, combined with worn rings. Could be someone spilled oil on it. Rebuilding the pump is not difficult. Idk the cost and availability of parts.
 
The 5120 could be configured with the air inlet filters pointing almost upside down from the factory.
Typically you don't see a lot of oil blown back into the filters when there is a bad breather valve, more of a pulse of air blown back through the inlet filter on the compression cycle.
Be sure that the crankcase breather vent is in operating condition and not plugged, also check for the correct grade of oil used in the crank case. The factory lists a range of oil grades that can be used but I have always used 30Wt non detergent oil.
Especially if it's a high duty cycle compressor.
 
I put a oil bath air cleaner on mine. I would no idea if it was backfiring oil into the filter. My theory was it was large to help muffle intake noise and any oil carried through would keep the top end from rusting.
Bill D
 
Doesn't seem to be much oil, but I don't like the idea of upside down filters- anything could end up in the cover bell then, including water. Since it is a pretty small amount I imagine filter stacks would allow it to just ingest the oil and pump it into the tank, where it would be removed by the auto drain. (its tank mounted) I'm going to add stacks and then I'll rout the auto drain to something where I can keep track of the amount, and keep a closer than normal eye on the oil level.
 
When the units were shipped new with the almost vertical down type intake filters the compressor was meant to be installed inside some type of weather proof structure/indoors. In fact (and I will probably catch hell over this) But all air compressors should not be operated where water from rain/snow, etc could be ingested into the pump or through the crankcase vent.
Belt slip on start up or during pumping could also be a problem especially on higher pressure units like a 2 stage compressor.
 
I would never install any compressor where it was not under at least a shed roof, but I still think it silly that they came this way. Strangely enough this one has a vent cap for the breather that would be fine fully exposed to the weather
 
I would say oil in the filters would almost certainly be a combinatioin of worn rings pumping oil into the top end and open /lifted inlets allowing the oil to blow into the filters....New rings would likely reduce the blowback.......as suggested it might also be out a breather ,again worn rings contributing to flow from the crankcase through the breather...High oil level is also a possibility,easily checked.
 








 
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