air compressor problem 2

Joined
May 30, 2010
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Location
North Carolina
I finally got around to taking apart my air compressor.
Kobalt 60 gallon oil bath compressor. 230v

It has a problem where it will run and slow down at about 65 psi, then stop at 90 and trip the breaker. It will not run past 90 psi, even after sitting over night. In a previous thread, it was suggested to replace the capacitors. I replaced the run and start capacitors and it exhibits the same issue.

I took apart head off tongight and i can't see a problem, the valve block seems simple enough, although you can't tell what the valves do hot. I suspect perhaps its the electric motor. ITs $289 or so, the valve block is $70.

I'm hesitant to spend $200 on an 8 year old $450 air compressor. Should i just cut and run for a newer , better compressor?




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those motors are available close to $200 online.

but I would consider a whole new air compressor and plumb in your old tank too perhaps.

could also upgrade.. call it a day. Even craigslist the old one for a little $$$
 
Wha would be the budget on new one you say better would that be bigger what's its intended use.
 
Whoa spaz.
The scenario that you have discribed is indicative of one of 2 things .
There is a check valve in the top of the tank on the line between the pump and the tank. That check is very important. With pressure in the tank remove the line from the tank to the pump. The check must hold the pressure in the tank and not be leaking.
Does the motor have 2 capacitors.
Some compressors have a start and a run capacitor. Could very well be a failed run capacitor. They are very easy to test even with a cheapy voltmeter.
 
You probably have a motor winding that partially shorted. If the compressor is in good shape and it had enough capacity for what you did I would vote for a new motor. Maybe go for one that is better than the one that came with it. If a quality motor costs $300 do you really think a new $500 compressor is going to have a $300 motor on it. My guess would be that you would have to go to a $1000 compressor, otherwise your just going to get the same thing you have or maybe lower quality as copper prices have gone up quite a bit in the last 8 years.
If you just want or need a bigger unit this excuse is as good or better than most.
You might also want to check your breaker and feeder ckt and all connections in the plug and receptical, if you have a loose wire it will lead to a voltage drop and corresponding current increase. And breakers do go bad and will trip at lower than spec draw.
 
Originally Posted by P10crew
Whoa spaz.

Does the motor have 2 capacitors.
Some compressors have a start and a run capacitor. Could very well be a failed run capacitor. They are very easy to test even with a cheapy voltmeter.


Originally Posted by P10crew
If it's just a capicitor those are like 10 bones



perhaps reading the actual post where he said he already replaced the capacitors would influence your reply?
 
Originally Posted by P10crew
Yes mr rand I missed that. Was doing the Evelyn wood speed reading.
Did he check the check?



Thanks i will check that. I can't find torque specs for the head. The bolts are 13mm head roughly matches a 11/32 diameter drill bit.

I'm going to guess 40lbs?
 
Originally Posted by spasm3
Originally Posted by P10crew
Yes mr rand I missed that. Was doing the Evelyn wood speed reading.
Did he check the check?



Thanks i will check that. I can't find torque specs for the head. The bolts are 13mm head roughly matches a 11/32 diameter drill bit.

I'm going to guess 40lbs?


I found the specs online, i was way off. 200 inch/lbs. I'll use 17ft/lb.
 
+1 on that! Scrap the thing or use it as an extra storage tank and get something decent like a Quincy, a no frills 2 stage 15 CFM is only 1200 bucks on the door.
 
It depends on how much money your wife will let you spend and how serious you are about needing a compressor. There are shops that rebuild motors but they may only do ones much larger.

If you do not want to invest a lot then get a new motor. If you can spend a lot extra get a 5 HP 2-stage.
 
Originally Posted by P10crew
Yes mr rand I missed that. Was doing the Evelyn wood speed reading.
Did he check the check?



I just pumped it up to 65 psi, let it cool, then unhooked the pipe from the pump head to the tank, no hiss at all.

So i think its the motor. I guess i'm in for a new compressor.
 
Ok then .... my recommendation would be to revert to Clines post.
Lol
There ain't no beating around the bush in this place.
Pert near fell on the floor
 
depends on how much air you need and how much you want to spend

You might be better going to Grainger and getting s new pump and motor- might be able to upgrade for less than a new unit
 
I'm going to see what the local electric motor repair show will charge. If it's over $150 , I'm in for a new unit.
 
Spaz if your bound and determined to give her one more go .
Google search Surplus center air compressor motor.
I buy a lot of stuff from them guys and very happy.
They Will have the motor you are looking for.
Good luck Brutha !
 
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