Air Compressor repair

[markhodges78]

I will be picking this compressor up tomorrow but it is missing some parts any one here that can help me source the parts ?

 

[GeoBruin]

North Star is Northern Tool's house brand. I would probably start with Northern Tool.

 

[The Cobbler]

you need a pressure switch with an unloader , a pressure relief valve, a regulator , manifold , and a magnetic starter etc. but before I spent money on that, I would test it to be sure it operates as it should . block off the ports in the tank, first see if it spins by hand , then direct wire the motor & see how it builds pressure. just keep an eye on it and not overpressure it .

 

[GeoBruin]

you need a pressure switch with an unloader , a pressure relief valve, a regulator , manifold , and a magnetic starter etc. but before I spent money on that, I would test it to be sure it operates as it should . block off the ports in the tank, first see if it spins by hand , then direct wire the motor & see how it builds pressure. just keep an eye on it and not overpressure it .

Well, now that I read your post, that's a much more helpful interpretation of the OP's ask.

 

[markhodges78]

you need a pressure switch with an unloader , a pressure relief valve, a regulator , manifold , and a magnetic starter etc. but before I spent money on that, I would test it to be sure it operates as it should . block off the ports in the tank, first see if it spins by hand , then direct wire the motor & see how it builds pressure. just keep an eye on it and not overpressure it .

Thanks for this ... he's asking 200.00 for it i figured if either the pump or motor was good it may be worth it

 

[djbmw]

Tap the bottom of the tank with a hammer and make sure its not rusted/thinning. If you have an inspection camera, insert it into the drain opening to look inside the tank.

 

[markhodges78]

Tap the bottom of the tank with a hammer and make sure its not rusted/thinning. If you have an inspection camera, insert it into the drain opening to look inside the tank.

I do have an inspection camera good call thanks

 

[GeoBruin]

It looks like an ABAC (Atlas Copco) pump and possibly a Leeson motor. Its a non-trivial investment to get it back up and running but at $200 for what's pictured, you're still way ahead. And that's a lot of compressor.

 

[markhodges78]

It looks like an ABAC (Atlas Copco) pump and possibly a Leeson motor. Its a non-trivial investment to get it back up and running but at $200 for what's pictured, you're still way ahead. And that's a lot of compressor.

This is exactly what I needed to hear... I don't mind replacing the parts as long as I can call on someone more nolagable then myself for the parts needed.

Thanks everyone.... stay tuned

 

[Citation]

It looks like you need a pressure switch with unloader ($30 will get you name brand unit). The switch doesn't need to have a big rating since it will only control the magnetic starter you also need (those are more likely to be $100+) . It looks like that motor doesn't have an overload so you need that as part of the mag starter. You will also need the check valve (likely under $40), piping, fitting and some wire. Overall, assuming the parts are good this is a very doable project and worth the $200. You will probably be $400-500 when the job is done. I think it could be done even for less but depending on sourcing etc the prices can vary widely.

 

[OccupantRJ]

7.5 hp single phase motors are not in the wild to be grabbed up often at all. I usually only find 5 hp and would personally buy it if nothing else to get the motor in my possession. As reference I read 50-200 for sale ads a day.

 

[gba2331]

You might find a working unit for $800 or so….

 

[The Cobbler]

for $200 I would grab it , but I would first make sure it spins and doesn't have any weird sounds

 

[toplessHO]

I bought my 6.5HP Devillbis on clearance for $450
Even with that I would think $200 is good if both main components are good.
Whats the oil like in compressor?

 

[markhodges78]

Ok so I bought it.... It actually has the motor starter on it picture below is did not hook it up ..so I'm still unsure of it'd condition.. but i do know that they was running it on a 30 amp breaker which they said got to the point that it keep tripping so they just unhooked it and it's been in the way..

 

[OccupantRJ]

Good going. Their breaker was a bit lightweight for a 7.5 hp motor. Charts call for around a 40 amp draw on that size single phase motor. You may have ended up with a decent compressor from their failures.

 

[markhodges78]

Good going. Their breaker was a bit lightweight for a 7.5 hp motor. Charts call for around a 40 amp draw on that size single phase motor. You may have ended up with a decent compressor from their failures.

Yeah they gave me the breaker as well and said it works fine at first then it just starts tripping... I think it just gets hot..

 

[markhodges78]

So it looks like I'm just looking at a pressure switch and unloader correct?

 

[The Cobbler]

get a pressure switch with the unloader circuit in it ( which is more common than not with it)
you also want an overpressure blow off

 

[markhodges78]

Will this work

Amazon.com

 

[The Cobbler]

site won't load for me

 

[markhodges78]

site won't load for me

try now

 

[The Cobbler]

something like this for a pressure switch and this for a pressure release

 

[markhodges78]

Thanks

 

[david3921]

something like this for a pressure switch and this for a pressure release

Please educate me on your choice for the pressure release. The above tag on the tank says that maximum pressure is 175 psi. The switch you suggested is 140-175 psi but the release is rated at 150 psi. Shouldn't that be 175 psi also?

 

[Citation]

Start with looking at the tank's rated working pressure (on a tag welded to the tank). It probably says 200psi. That's the max the rated pressure for the tank. The 175 on the sticker is the max pressure the pump will put into the tank. You want a blow off valve that's between those two numbers. You can always adjust the pump pressure down via the pressure switch. You can't (safely) exceed the tank's rated pressure. So your blow off valve needs to be say 10 psi or more under that max. You also want it a bit above the pump cut off so you don't nuisance trip the blow off valve. That would cause the motor to run continuously.

Almost all pressure switches can be adjusted so if you can't find one with the correct settings just adjust it. When looking at switches do pay attention to how the wires come in/out and where the unloader goes. Lots of small variations.

This Condor switch is close to what you want and might work (check those things I mentioned above)
https://www.grainger.com/product/3EYT8
It cuts out at 160 psi vs 175 so the compressor would leave a bit of working pressure on the table. Not really an issue for most needs. It can be adjusted up.

Good that the compressor has the starter. Does it have an overload fuse or breaker? You need some type of motor overload protection. On smaller compressors it's often a button on the motor. On larger units is typically connected to the starter.

 

[Old Man Roger]

A bad pressure switch unloader valve can cause a compressor to trigger breakers. Its job is to release pressure from the pump so the motor can start without being under a load.

 

[The Cobbler]

The switch you suggested is 140-175 psi but the release is rated at 150 psi. Shouldn't that be 175 psi also?

good catch. the overpressure should be a bit higher than the shut off pressure. I would probably not go to the max pressure on the tank, a pressure of 130 psi is probably enough , but to each their own .

 

[markhodges78]

Sooo I wired it up this evening to see if it ran and it did But the pump has a knock ... so it looks like im going to need a pump ...... I can get this one which I believe is the direct replacement https://a.co/d/fH5bA98 but if possible Id like to get something a little cheaper. I even considered one from harbor freight..

Any suggestions ?

 

[OccupantRJ]

First, make sure the valves and top of piston are free from carbon, which can cause one to knock. There was a 25 hp V4 compressor at work that knocked home sweet home on startup for 30 years. After that it ran fine for ten hours a day. It does not cost money to investigate it and there is always learning to be done.
Gene Winfield said that every day is a school day, and I agree with that.

 

[markhodges78]

Oh, sure thing. You can bet I'm gonna dig into it.
I wish this did stop knocking. It is a continuous knock i did not have a gauge on it, but I did put my finger over it. And when I let my finger off after about 5 seconds, there was a lot of air made.

 

[OccupantRJ]

Rock the flywheel back and forth about an inch on the perimeter in various positions of piston stroke to see what you hear and feel.

 

[markhodges78]

Rock the flywheel back and forth about an inch on the perimeter in various positions of piston stroke to see what you hear and feel.

I did that last night and there is movement a little and it's clanking. So I believe it's something with the crank and bearings, which I have not been able to find parts for the pump

 

[OccupantRJ]

A couple of friends have the 5 hp designated pumps from Harbor Freight and seem satisfied with them. I fabricated output line adaptors for both of them to attach to their existing compressor input lines. With the 7.5 motor you could run it at it’s upper rpm limit with a proper sized motor pulley. It then becomes a matter of whether the pump has the cfm output you need.

 

[markhodges78]

A couple of friends have the 5 hp designated pumps from Harbor Freight and seem satisfied with them. I fabricated output line adaptors for both of them to attach to their existing compressor input lines. With the 7.5 motor you could run it at it’s upper rpm limit with a proper sized motor pulley. It then becomes a matter of whether the pump has the cfm output you need.

Honestly I would use it for air tools ( DA's sand blaster plasma cutter ) the CFM's on the current pump is crazy high and even though its not needed id rather have as much of it as possible lol

 

[markhodges78]

I feel like for what I have in it I could put a H,F pump on it and run it a few years our I could just put a northern on there and hopefully be good for a while

 

[RTM]

So I believe it's something with the crank and bearings, which I have not been able to find parts for the pump

Not knowing North Star (or compressors for that matter), I doubt it was made solely for them. I suspect it is a compressor that is sold under one or more names, so I would try to track down other brands that are the same, or that fit. May take some work to dig up the numbers.

 

[stillnostrebor]

I like the idea of running the pump you have if at all possible, but that said, I just re-pumped my compressor with the current 2-stage pump from HF and it works surprisingly well.

 

[markhodges78]

I could do this one for 600 but would have to change the pully on the motor to slow the pump down some https://a.co/d/9gR9XIY

 

[markhodges78]

Any opinions on which pump i should replace mine damaged pump with


Direct replacement

https://www.northerntool.com/products/northstar-air-compressor-pump-2-stage-569cc-22-9-cfm-at-max-psi-45932

Have to change pulley to decrease pump speed

https://www.northerntool.com/products/northstar-air-compressor-pump-2-stage-2-cylinder-24-4-cfm-90-psi-175-max-psi-4593100

Decrease in cfm and will have to reconfigure some things

https://www.harborfreight.com/5-hp-175-psi-2-stage-v-style-cast-iron-air-compressor-pump-59672.html

Would like some input