Okay, so, I'm trying to help out my instructor/LDS owner with his compressor, and I could probably use a few words of advice. I'd like to thank in advance anyone who reads through all this. The unit is a Mako, model number 5406BS-C. Appears to be a Mako 5406E block. It was reconditioned (whatever that entails) before he purchased it around 5 years ago. Since then only about 450 hours have accumulated on the hour meter. Previous number of hours is unknown.
When the compressor is powered on, it only runs for about 5-8 seconds--as soon as it begins to build air pressure in the 4th stage, it shuts down. The entire time it's running, the oil pressure gauge does not rise at all (specified oil pressure on the unit is 1000 psig). The unit is equipped with a low oil pressure shutdown switch, so at least that's working as intended. A compressor technician came out last week, disconnected the oil discharge line from where it enters the pressure regulator, and found no oil discharging from the line with the unit running (I did the same). He quoted somewhere north of $1000 to replace the oil pump.
Today, I removed the oil pump from the unit, as well as the cover plate exposing the end of the crankshaft that drives the pump. For those unfamiliar with the unit, there is an eccentric cam on the end of the crankshaft that pushes up and down on the end of the pump to power it, no gears or chains to drive it. Anyway, I found the bearing that's pressed onto the end of the crankshaft, which actually makes contact with and drives the oil pump, laying inside the chamber behind the cover plate. I checked everything for damage and found none, pressed the bearing back on, reinstalled the oil pump, and turned the compressor by hand to make sure the pump was being driven through its full stroke and everything turned freely. Then I reinstalled the cover plate, refilled the oil, started the unit...and still no oil pressure. Removed the cover plate again to make sure everything was still in place and it was. And, still no discharge from the high-pressure oil line, before the pressure regulator.
At this point I'm almost stumped, except for one idea. I'm thinking maybe the pump is just full of air and needs to be primed, so tomorrow I plan to disconnect the oil discharge line from the regulator (located about 6-10" above the pump), and use a hand-held vacuum pump to pull oil through the pump and up the line and hopefully suck any air out of the pump, while turning the unit a few turns by hand to suck out any pockets. But if that doesn't work, I really won't have a clue. I just have a hard time believing that the oil pump failed, because as I discovered today it wasn't even being driven.
So, getting to the point, is anyone here familiar with these things? Anything I might be missing, or any pointers? Do the oil pumps usually fail on these? Thanks in advance to anyone who might have some insight.
When the compressor is powered on, it only runs for about 5-8 seconds--as soon as it begins to build air pressure in the 4th stage, it shuts down. The entire time it's running, the oil pressure gauge does not rise at all (specified oil pressure on the unit is 1000 psig). The unit is equipped with a low oil pressure shutdown switch, so at least that's working as intended. A compressor technician came out last week, disconnected the oil discharge line from where it enters the pressure regulator, and found no oil discharging from the line with the unit running (I did the same). He quoted somewhere north of $1000 to replace the oil pump.
Today, I removed the oil pump from the unit, as well as the cover plate exposing the end of the crankshaft that drives the pump. For those unfamiliar with the unit, there is an eccentric cam on the end of the crankshaft that pushes up and down on the end of the pump to power it, no gears or chains to drive it. Anyway, I found the bearing that's pressed onto the end of the crankshaft, which actually makes contact with and drives the oil pump, laying inside the chamber behind the cover plate. I checked everything for damage and found none, pressed the bearing back on, reinstalled the oil pump, and turned the compressor by hand to make sure the pump was being driven through its full stroke and everything turned freely. Then I reinstalled the cover plate, refilled the oil, started the unit...and still no oil pressure. Removed the cover plate again to make sure everything was still in place and it was. And, still no discharge from the high-pressure oil line, before the pressure regulator.
At this point I'm almost stumped, except for one idea. I'm thinking maybe the pump is just full of air and needs to be primed, so tomorrow I plan to disconnect the oil discharge line from the regulator (located about 6-10" above the pump), and use a hand-held vacuum pump to pull oil through the pump and up the line and hopefully suck any air out of the pump, while turning the unit a few turns by hand to suck out any pockets. But if that doesn't work, I really won't have a clue. I just have a hard time believing that the oil pump failed, because as I discovered today it wasn't even being driven.
So, getting to the point, is anyone here familiar with these things? Anything I might be missing, or any pointers? Do the oil pumps usually fail on these? Thanks in advance to anyone who might have some insight.
