Air compressor sounds like a dying turkey on startup, Help!

[JZeeker007]

So i have a 60gal sanborn air compressor with a 3.7hp pump. I am on my second pump as I thought the 1st pump was going bad. But the second pump is doing the same thing, but wasnt right away. When it kicks in and starts up it sounds like a dying turkey, chirps and gobbles for about 45-60 seconds and then is smooths out and runs and pumps just fine. Any thought? Oil is full and clean. Belt seems to be tight. I cannot tell if its the pump semi seized and needs to loosen up or the motor just not spinning it up right. But every time it will smooth out and sound normal. Any help or ideas would be greatly appreciated. Thank you in advance!

 

[The Cobbler]

since the symptoms are the same with the new pump, doubtful it's the pump

does it do it with no pressure in the tank?
have you tried running the motor without the belt attached & see how it sounds?

could be a bad start switch, bad capacitor , the compressor not unloading.
hard to tell by the info given

 

[JZeeker007]

I will have to try those and see the outcome. What do you mean by compressor not unloading? Thanks.

 

[The Cobbler]

there is an unloading system in the compressor to let the air pressure bleed off of the compressor head itself so when it re starts it is only under atmospheric pressure rather than full tank pressure. if the system is faulty and there is tank pressure at the head it will cause poor/slow/hard starts

 

[seber]

Those are all good suggestions. Also check the belt condition for glazing.

 

[Mick56]

I would check the belt, too. It can be tight, and still slip. Look at where the belt is on the pulley, the belt should be a little above the groove. If the belt is down in the pulley, it is probably worn out.

 

[Tallpilot]

there is an unloading system in the compressor to let the air pressure bleed off of the compressor head itself so when it re starts it is only under atmospheric pressure rather than full tank pressure. if the system is faulty and there is tank pressure at the head it will cause poor/slow/hard starts

Listen for a hiss when it shuts off; that's the unload.

 

[JZeeker007]

Thank you with all your input... I wont get time to play around with the compressor until this weekend. I will let you guys know that outcome. Again I really appreciate all the ideas!

 

[redmondjp]

I'd remove the check valve at the inlet to the tank and inspect it carefully. It could be defective/sticky and allowing the tank backpressure to load up the pump output, before it settles down/unsticks.

 

[Mr_B]

Bad start capacitor is a common one .

 

[driz]

Those pressure switches die a lot as someone said before. If you find yours Is dead don’t just run out and buy one from the $$$$ company. When my Chinese German Campbell hausfield died back 5 years ago I noticed it looked exactly like the one on my well pump. CH 50 vs. Amazon generic $17; same thing. If your starting capacitor is toast same sort of deal or get one at your local AC motor shop. Save the cash for A more deserving charity, you.


Sent from my iPad using Tapatalk

 

[Bluejoe]

If you start looking at it watch out for the capacitor it holds a charge and can give you a shock.

 

[JZeeker007]

I had a free moment lastnight and ran down to the shop. It does hiss/unload pressure after it kicks off. I did notice as i was standing right next to it when it kicked in, smelling smoked belt. So it might be slipping at first then catches up. Or the pump is not rotating smooth on start up and causing the belt to slip. So I will pull the shroud off and check the belt at some point this weekend.

 

[The Cobbler]

just be careful to unplug it while you're around the belt . easy to lose fingers!

 

[bczygan]

just be careful to unplug it while you're around the belt . easy to lose fingers!

My mother, (A pianist) did!

 

[Mick56]

A way to tell if the belt is slipping, is after it shuts off, unplug it and feel the pulley, if it's hot, the belt is slipping.

 

[JZeeker007]

Sorry i havent been able to get to the compressor issue yet. I have been putting out other fires. I hope to dive into it soon and will post back. Thank you all for all the input and advice. I really have enjoyed this forum for quite awhile and find that there are so many great people on here willing to give advice and wisdom.

thanks you!

 

[GrayFlattop]

I'd second the suggestion of the check valve in the tank if the unloader is functioning.

Or a valve in the head surrendered.

Or you have a bad bearing (hopefully you have oil in the crankcase).

 

[connoraa]

I know this is close to 8 years later, but did you ever figure out what was causing the issue? My compressor is doing the same thing!

 

[The Cobbler]

belt . neighbor at the volunteer warehouse asked me to look / listen to his compressor . the single belt had shined up on the edges causing it to slip . It wasn't too badly worn other than it was shiny . It should really have 2 or 3 belts but in todays cost saving world, that's what you get
A new belt solved the issue

 

[welder4956]

I know this is close to 8 years later, but did you ever figure out what was causing the issue? My compressor is doing the same thing!

OP was last seen Oct. 11, 2018. I'm guessing he fixed the problem and never came back.

My compressor makes similar noises when the belt is loose enough to slip. About ever 2-3 years the belt loosens due to all the vibrations. That's the first thing I would check.