Hydrovane 501 Strange Noise

[CoolB]

Hello, I have a Hydrovane 501 compressor that makes a strange sound as it nears shut off pressure. I have had problems with the compressor due to a terrible rebuild from a local shop. Those problems have since been corrected. The last problem was resolved when the oil seal was replaced. Afterwards, the noise started. I thought it may be the internal pressure valve releasing, but the head pressure gauge continues to climb normally when the noise starts. The compressor runs normal until the tank pressure reads 115lbs and then a loud buzzing sound starts. The pressure continues to build as it should and the compressor cycles off at 125lbs. When the compressor cycles back on, the noise does not start again until 115lbs. There is clearly a problem that is causing this loud buzzing sound, but I don't know what it is. I hope some one has some ideas on what this could be.

Thank you for the help

 

[tigler]

Is the noise coming from the motor or pump ?

 

[CoolB]

It is difficult to tell, but I assumed the pump. I can hear and feel it. Is there something that would make such a noise in the motor that seems to be triggered by pressure? Perhaps a capacitor engaging?

Thanks for the reply!

 

[tigler]

Won't be anything like that. there is a pressure relief valve on the end plate which could conceivably cause a noise like that but it could also be vane rattle if you say you can feel it. Thats pretty terminal as far as I know as it means the rotor, the vanes or both are worn, which is pretty much the core of the machine.

 

[CoolB]

The vanes and rotor are in good shape. I am familiar with the location of the pressure release. The way I understand the function of the pressure release, it vents out the intake if there is excess pressure. If this occurred, wouldn't the head pressure gauge drop at the same time? In my case, the gauge continues to climb until the proper shut off point. That is what is confusing me. The reason I asked about a capacitor engaging is because of the sound which is similar to a buzzing electrical sound with a vibration. I am unsure of how something like that could occur only at the end of a cycle. The sound can be faintly heard for 10-15 seconds before it seems to fully kick in, like a pressure valve may work as it approaches too high of pressure. Do you know of a way to test the pressure valve? I doubt I can replace it as parts seem to be hard to find. Any trouble shooting ideas would be appreciated.

Thanks for you help

 

[whitestar]

Hi CoolB

I had this problem - in fact it's just started again.
Turned out to be a faulty run capacitor. I replaced half the service items including the bearings before I realised what it was. I replaced it with a cap from Maplin.

Hope yours is as straightforward

Good luck !