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By: Joseph Schneider,
Duluth,Mn.USA
I have a Hitachi 2 HP 4 Gallon Oil-Lubricated Air Compressor Model # EC12.
The motor sounds strong, but I’m getting hardly any air in my tanks. I check the oil and and looked at the gasket and it seems to look ok. Air is coming out of the top of motor. Don’t know if that is normal.
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Hello Joseph. No, air isn’t supposed to come out of the top of the motor. This symptom makes me think that you have a valve failure, and what may be happening (since air follows the path of least resistance) is that the air that’s being ingested by the compressor piston is being blown right back out the same inlet port since it’s easier for the air to flow that way, than down past a check valve into the tank.
Why won’t your compressor build air pressure? There are a lot of reasons found on the troubleshooting page of this site which may also be a cause, though I suspect it’s the reed valve that is causing your compressor problems.
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Hi bill
by: Joseph
Is the reed valve the cylinder shape by the gauges that you can pull to release the air?
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No, that’s the PRV, Joseph. The reed valves are located inside the intake hole (usually there is an intake filter screwed into the intake port) and they control the air in, and stop the air out, so that the air can be forced into the tank.
Hello Bill, I recently purchased an Hitachi 4 gallon ec99s off of Amazon. Not a refurbished unit but a unit that was a return in its original box. The company I purchased it from states that all of them have been tested and work great. I received the unit very timely and it appeared as if it was never used. I plugged it in and the motor ran well but it never built pressure. I contacted the company and they apologized and sent a replacement immediately not requiring the original in return. I plugged the second unit in and it… Read more »
When you say air is escaping the “start valve”, might that also be known as a pressure switch? Where on that valve is air escaping? Is there an unloader valve on the side of the pressure switch? Is air coming out there. If so, and though I cannot see from any of the photos I found, where the metal pipe from the top of the pump enters the air tank, is there a fitting there with another line that goes over to the pressure switch? If so, and air is escaping out of the pressure switch (start valve) it’s likely… Read more »
I pulled up a parts diagram and it is calling the valve on the head, opposite the intake and filter, a start valve. I think the pressure switch is lower by the tanks. So the air is coming out off the top from a valve that is screwed into the air fins on the head. You can’t see it without removing the shroud.
OK, that’s likely the cold start valve. It’s supposed to bleed air when the compressor stops, and briefly when the compressor starts. That it’s not shutting off automatically makes it suspect, and given that it’s the second compressor with the same problem, it may be that they got a bad batch.
You will find a number of sources for these types of valves if you Google “air compressor cold start valves”. Too bad that you have to do this at all.
Ok, thank you for the help.