# Motor won’t turn after compressor rebuild.



## Stangfire (Oct 19, 2021)

Hi everyone.

my compressor that I have used for years started to blow oil out the line. So I bought a rebuild kit and put new rings, gaskets and a newer used valve plate in it. Fresh oil also.Put it all back together and it turns over by hand no problem. However when I plug it in it just hums till it pops the breaker. I tried helping it and spun the compressor by hand and it started but only ran for a few seconds till it popped the breaker again. It ran fine before this. Did I put something together wrong and create too much compression? Should I start working backwards and put some old parts back on? I’ll post some pics I have.


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## Stangfire (Oct 19, 2021)




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## iowagold (Jan 22, 2020)

hummm
start by disconnection of the belt
does the motor run by its self?

did you get the reed place in right?
one way is dead head the other is flow.


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## Stangfire (Oct 19, 2021)

iowagold said:


> hummm
> start by disconnection of the belt
> does the motor run by its self?
> 
> ...


yeah motor runs perfect with no belt. It also ran perfect before I put the new parts in. I’ll have to take the reed valve plate off and double check it.


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## iowagold (Jan 22, 2020)

there is only a few things that will do that issue.
the reed is the main one.
make sure the reed is still in good shape.
some do not like hard back pressure.


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## Stangfire (Oct 19, 2021)

iowagold said:


> there is only a few things that will do that issue.
> the reed is the main one.
> make sure the reed is still in good shape.
> some do not like hard back pressure.


Thanks.

I’ll double check the valve plate and make sure I have it orientated correctly. If it’s correct and still not turning then I’ll put the old valve plate back on and try it. If it still doesn’t turn after that then it must be something with the rings. Maybe they are too tight.

I’ll undo things one step at a time until it’s turning because it had no problems turning before.


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## Stangfire (Oct 19, 2021)

I took the head plate off and it still wouldn’t turn on its own. So for sure it’s something with the new rings. So I took the rings off and doubled checked I had them oriented correctly. Instructions said the DOT on the rings goes up. That’s also bevel side up. I had the oiler ring butted up against itself. It has a red and green painted ends. So I overlapped it one notch and tried that. So I put it all back together and plugged it in. It would not start but I spun it by hand to get it going. It started and I ran it for 20 minutes. I unplugged it and plugged it back in and won’t start. So these new rings are causing it to be too tight I guess. They are exactly the same size as the old ones. How should the oil ring be with the red and green ends? Butted up? Over lapped?
So frustrating. Guess I’ll put all the old rings back in and try it.


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## iowagold (Jan 22, 2020)

measure them!
just remember the rings have the large dia to the top of the piston on the taper.

is the ball free on the oil or crankcase vent?
it has to breath.


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## Stangfire (Oct 19, 2021)

iowagold said:


> measure them!
> just remember the rings have the large dia to the top of the piston on the taper.
> 
> is the ball free on the oil or crankcase vent?
> it has to breath.


What do you mean by large diameter to the top? Bevel side up? I’m installing them this way. The DOT/bevel/taper is up.


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## Stangfire (Oct 19, 2021)




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## Stangfire (Oct 19, 2021)

This is the oil ring. In this pic it’s butted up with no over lap.


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## iowagold (Jan 22, 2020)

up side down
taper is to the bottom or crankcase side


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## Stangfire (Oct 19, 2021)

iowagold said:


> up side down
> taper is to the bottom or crankcase side


I'll give that a try. Instructions said the DOT/taper goes up but who knows. Unfortunately I didn't take pics of the old ones.


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## stevon (Mar 5, 2019)

Stangfire,

Is there way you can see the rings end gap installed in the cylinder? Push the ring in the bore about 1" without the piston If the ring end gaps are not large enough, the rings will bind and overload the motor. I don't know how you would find out the factory end gap specs but I know they are published for gas engines, lawn mower, car, motorcycle and such piston devices. Also could you measure the amps when running compressor under load? It should be less than the 15 amps FLA listed on the motor. I would start there myself, a $15 dollar ammeter from Harbor Freight would work for that. The amps drawn could help you in the right direction to a solution. Remember to clamp on only one of the hot leads when testing. What grit did you use to "hone" clean up the cylinders? also did you do the criss cross pattern?














The scratches act like races in a ball bearing, the oil being the balls. This accomplishes two functions, 1. lubrication to prevent wear and excess friction 2. also makes a seal. Without the scratches trapping the oil, the rings are just metal on metal. and oil is just scraped off.


Stephen




Stangfire said:


> I'll give that a try. Instructions said the DOT/taper goes up but who knows. Unfortunately I didn't take pics of the old ones.


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## Stangfire (Oct 19, 2021)

stevon said:


> Stangfire,
> 
> Is there way you can see the rings end gap installed in the cylinder? Push the ring in the bore about 1" without the piston If the ring end gaps are not large enough, the rings will bind and overload the motor. I don't know how you would find out the factory end gap specs but I know they are published for gas engines, lawn mower, car, motorcycle and such piston devices. Also could you measure the amps when running compressor under load? It should be less than the 15 amps FLA listed on the motor. I would start there myself, a $15 dollar ammeter from Harbor Freight would work for that. The amps drawn could help you in the right direction to a solution. Remember to clamp on only one of the hot leads when testing. What grit did you use to "hone" clean up the cylinders? also did you do the criss cross pattern?
> 
> ...


Yeah I checked the ring end gap using that method. It's exactly the same as the old rings. I did not hone the cylinder. I didn't think it was required as it had no scoring or marks.


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## stevon (Mar 5, 2019)

Stangfire, 

If you can turn the pump by hand easily, the next diagnostic procedure is to measure the amps unloaded, then under load. You could have a bad run capacitor or winding in the motor. Possibly when you tightened up the rings the problem just surfaced. I would replace the check valve and air filter while I was working on it. They are both relatively cheap

Stephen




Stangfire said:


> Yeah I checked the ring end gap using that method. It's exactly the same as the old rings. I did not hone the cylinder. I didn't think it was required as it had no scoring or marks.


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## Stangfire (Oct 19, 2021)

I tried everything last night. Put all the old parts back in. I can turn the pump by hand easily. So I took the motor off and will have it tested. Maybe by coincidence something happened to the motor at the same time. It just doesn’t want to start on it’s own. I have to give it a spin to get it going.

I’ll report back the findings of the motor.


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## Stangfire (Oct 19, 2021)

Turns out the starting capacitor on the motor is bad. Not exactly sure how that happened at the exact same time I changed the compressor rings.

Also the motor bearings are rough so having them replaced.


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## stevon (Mar 5, 2019)

Stangfire,

Sounds like you are making progress! Keep us posted

Stephen



Stangfire said:


> Turns out the starting capacitor on the motor is bad. Not exactly sure how that happened at the exact same time I changed the compressor rings.
> 
> Also the motor bearings are rough so having them replaced.


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## Stangfire (Oct 19, 2021)

The shop put a new starter capacitor, bearings and cleaned my filthy motor. Guy said it’s a very good, expensive motor and to take care of it and hang onto it.

Put it back together and it fired right up! So all good thanks for all the replies.

Side note, what’s some tips and tricks to reduce oil in the air hose?

Should I add a filter of some sort? I have nothing at all right now.

How often should I change the oil? Do I just buy air compressor oil?


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## iowagold (Jan 22, 2020)

yea a oil water separator dryer is a good idea
and yes on air filter fine micron style.


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