hissing compressor

[rieferman]

Porter cable pancake compressor. When it fills the first time, it hisses/leaks to the point where it causes itself to refill again almost immediately. After the first fill/refill cycle, it doesn't hiss anymore for the remainder of my session. Also, it will hold air for days on end without drop in pressure. What the heck should I look for as a fix?

 

[kams1973]

That's the cold start valve

 

[rieferman]

School me, I'm all ears

 

[kams1973]

A cold start valve on an air compressor is designed to allow the motor/pump combination to start up "unloaded." Basically is allows everything to come up to speed before puting a load it. This allows for lower starting torq and amperage.

Here's a link that shows what a cold start valve looks like.http://compare.ebay.com/like/260750035696?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&rvr_id=219718971844&crlp=1_263602_309572&UA=WXI7&GUID=cf3fb57312e0a0a9f6569a46ffd3233b&itemid=260750035696&ff4=263602_309572

 

[brrman]

When is the last time you drained your tank? I was having the same problem and after draining (there was a fair amount of water buildup) it was fine.

 

[rieferman]

Ok, I'm not sure this compressor has the cold start valve that was mentioned. I only say that because for 2+ years there was never any hissing as I described in my original post - if there was a valve that was supposed to do this, it would have done it the whole time.

I did drain it last night for the first time in a long time, and there was about a cup of water in there! YIKES. I didn't get to fire it up afterwards because it was late, but I'll test 'er out this evening and report back.

Thanks guys!

 

[Zrexxer]

Porter cable pancake compressor. When it fills the first time, it hisses/leaks to the point where it causes itself to refill again almost immediately.

Basics, first. Where is it leaking from?

 

[rieferman]

As you look at the front of the compressor, there are two gauges. The left hand one tells you how much pressure is in the tank, and the right hand one tells you what pressure you have it set to. (sorry for my non-technical explanation!) There's a plastic cover that surrounds both of those. The air hisses and I can feel it next to the left hand gauge (but I haven't attempted removing the cover to determine the exact air exit point).

Should I remove the cover and check anything out?

edit: also, reminder that I have not yet tested whether draining the water out helped anything.

 

[antinym]

I have the portable PC, too. there's no cold start valve, also known as an unloader valve.
If the hiss is coming from the gauge, that's probably your problem. If it's coming from inside the plastic case, then it's probably the check valve. (that's the fitting on the other air connection into the tank)

 

[c_mccann]

Pressure switch. It is malfunctioning. It is a spring actuated unit, pretty basic- sounds like a seal, or the armature is hanging up. You can troubleshoot it if you can get the cover off it, or just replace it. Square D makes a fine pressure switch.

 

[Zrexxer]

edit: also, reminder that I have not yet tested whether draining the water out helped anything.

Draining condensate out of the tank is not going to do anything related to pressure leaking down and making the pump cycle again. You've got a leak. You're going to have to figure out where it's leaking from if you intend to fix it. My money's on c_mccann's suggestion, it's probably the pressure switch. They're a fairly common service item.

 

[rieferman]

Cool, I have to reclaim my shop tonight (just finished gutting and rebuilding the kitchen, so it's CRAZY in my shop right now!) and will do some investigation and report back to the group in the morning. Thanks again fellas!