|
Roger here, my name has been reserved.. Anyway, just make sure there is an oil pressure gauge on it and that it comes up to pressure almost immediately. Anything 15psi to 30psi is fine for oil pressure. Generally, listen for knocks, air hissing or funny vibration. When it shuts down, listen for a short blast of air that is telling you it is unloading properly. Depending on the motor type, it may coast down quietly, or it might make a loud "graunching" sound and bring the pump to a quick stop. These motors, at least as they have been described to me, send a jolt from the capacitors into the windings to stop the rotor from spinning. Some people refer to them as "saw motors". I am not sure if either description is accurate, but the sound, and sudden stop may lead you to believe there is something seriusly wrong with the motor, when in fact, it is fine. I still hate them for compressor applications though. If it is a Quincy, and a two stage pump, see if there is a safety relief valve in the front-top of the cylinder head. If it is there, pull it while the compressor is running. If there is no air escaping, there are low pressure valve problems. If the valve is missing and the port is plugged, suspect that there may be high pressure valve problems. If you can, bring a 50 or 60 psi air gauge with you, mounted on a 4" long or so 1/4" pipe nipple and screw it into the port and see what pressure you are getting there. Look for bewteen 15 to 30 psi. This is just a rule of thumb. Higher interstage pressure is probably ok, as long as it is below the pop-off pressure of the safety valve. Other than that, it's just listen for knocks and look for oil leaks. unless it's well and truly knackered, it's probably worth getting if the price isn't too steep. I wouldn't spend too much on anything I couldn't completely strip down first. Having said that, I have been pretty lucky with the look and listen technique when buying motorcycles (so far)!
|
