What's new
By:
Filters

Air compressor help

wvracer821

wvracer821

Well-known member
Joined
May 27, 2020
Member Number
1546
Messages
730
Loc
Morgantown, WV
I got a Kolbalt 80 gallon compressor for free from a friend. They took it out of service years ago because the motor was bad. It sat in his garage since 2016 until I picked it up. I put a new Chinese 5hp, 230v motor on it today and fired it up.it starts up normally but when It gets up to about 40 psi it slows to a painful speed. Any idea on what’s going on? Is there something in the compressor head I need to check out? Maybe my wiring is fucked? It does have oil in it.
 
Did you wire the motor correctly? (Motor usually has a diagram.) Is the check valve working?
 
Do you know if it was a 5hp that you took off it?

Does it continue to work past 40 psi? Or stop? Or trip the breaker?
 
It was a 5hp motor that came off. I shut it down in fear of damaging something. Maybe I’ll try to let it run and see what happens
 
Check the running current with a clamp meter. That'll give you some idea if it's struggling or not.

Edit: Is the motor rpm correct for the pulley/belt system employed?
 
So, I am once again asking for your knowledgeable support.

When the motor starts when there is some air already in the tank it arcs inside it repeatedly and it kinda shutters on and off almost like it’s overloading or something. I’ve triple checked that the wiring is correct. Maybe I got a lemon for a motor?
 
wvracer821 said:
Here is a short video of what I’m experiencing
Click to expand...
I don't hear a bleed off.

When you switch it off, is there a lever or valve that released the pressure from the compressor head?

Releasing that pressure allows the compressor to restart without resistance.

When mine shuts off I hear a hiss of air for a few seconds as it bleeds that pressure.
 
Yeah when I bleed off the tank to 0 it starts and runs fine all the way up to the 135 psi when it shuts off.
 
That looks like the centrifugal starter not fully releasing. Possibly not getting up to speed fast enough or just Chinese quality.

Is that a true 5hp motor or is it one of the big box store "5 hp" varieties?


Run it til it smokes and in the meantime, keep an eye on CL or ebay for a good, name brand motor and maybe add a magnetic starter to it.
 
It’s a “Vevor” brand Chinese unit from Amazon.

VEVOR 5 Hp Electric Motor 3.1 KW Rated Speed 3450 RPM Single Phase Motor AC 208-230V Air Compressor Motor Suit for Home and Small Shop Air Compressors https://a.co/d/c7LBD1V
 
Maybe a bad check valve causing pressure to be left on the head even after the switch bleeds it off? I might try replacing a check valve to see if it helps.
 
I pulled the check valve and it looks like it’s seen better days.
image.jpg
 
If the check valve were bleeding back, the pressure release would continue to bleed down until the tank emptied.


Obviously it needs to be replaced any way, but I doubt that's the problem.
 
I took the check valve apart, cleaned it up and confirmed it is now sealing. I’m pretty sure the motor is junk which sucks. I found a local place that rebuild’s electric motors and I’m going to drop off the original one and this one to get reworked. Hopefully that’s not crazy expensive.
 
arse_sidewards said:
I once put a 120v plug on the end of a small 220v compressor that didn't come with a power cord. ~40psi was about where it stalled. :laughing:
Click to expand...
In older farm buildings, at least in Maine, 2 prong, 240v outlets were common. Just a regular outlet that sometimes was painted red or had a red cover, but often not.

I found out the old 120v 1960s put-put-put air compressor goes damn fast if you plug it in the wrong outlet.

No idea why those outlets were common.
 
wvracer821 said:
It’s a “Vevor” brand Chinese unit from Amazon.

VEVOR 5 Hp Electric Motor 3.1 KW Rated Speed 3450 RPM Single Phase Motor AC 208-230V Air Compressor Motor Suit for Home and Small Shop Air Compressors https://a.co/d/c7LBD1V
Click to expand...

5hp for $166?? Thats pretty cheap. I wouldnt be surprised if it was just a cheap chinese pos. Grainger lists a 220v 5HP motor at $700.

Edit:

I went back and looked, and thats a 5hp SPL motor. That means peak HP, not average. Its probably more like 3HP.


www.inyopools.com

What does HP SPL mean on a Pool Pump Motor Label? - INYOPools.com - DIY Resources HP SPL

If your pump motor lists a 5 HP-SPL, you are more than likely dealing with a 2 to 4 total horsepower motor. I know this isn't very clear, but the thing that helps us find the right match is the amp rating. Of course, you can inflate, conflate, and mitigate that horsepower number, but Amps are amps.
www.inyopools.com www.inyopools.com

Heres a chart breaking down HP based on voltage and amperage
www.electrical4u.net

Horsepower (HP) to Current (Amps) Conversion Chart | Electrical4u

Below table is calculated amps value for the respective standard motor horsepower rating. The table first column indicates the DC current and followed by the
www.electrical4u.net www.electrical4u.net


According to that, a 220v 5HP motor should be pulling 18.7a not 15a. So its more likely that your motor is 3-4HP.
Knowing that they are exaggerating the HP rating, i wonder what else they cheaped out on.
 
Last edited:
reptillikus said:
5hp for $166?? Thats pretty cheap. I wouldnt be surprised if it was just a cheap chinese pos. Grainger lists a 220v 5HP motor at $700.

Edit:

I went back and looked, and thats a 5hp SPL motor. That means peak HP, not average. Its probably more like 3HP.


www.inyopools.com

What does HP SPL mean on a Pool Pump Motor Label? - INYOPools.com - DIY Resources HP SPL

If your pump motor lists a 5 HP-SPL, you are more than likely dealing with a 2 to 4 total horsepower motor. I know this isn't very clear, but the thing that helps us find the right match is the amp rating. Of course, you can inflate, conflate, and mitigate that horsepower number, but Amps are amps.
www.inyopools.com www.inyopools.com

Heres a chart breaking down HP based on voltage and amperage
www.electrical4u.net

Horsepower (HP) to Current (Amps) Conversion Chart | Electrical4u

Below table is calculated amps value for the respective standard motor horsepower rating. The table first column indicates the DC current and followed by the
www.electrical4u.net www.electrical4u.net


According to that, a 220v 5HP motor should be pulling 18.7a not 15a. So its more likely that your motor is 3-4HP.
Knowing that they are exaggerating the HP rating, i wonder what else they cheaped out on.
Click to expand...

Likely the same type of motor that came on it originally. Most of the box store compressors are sold as "peak" hp.
 
If you want to quickly demystify the mixed HP claims, compare the cfm@90psi ratings and/or amperage (@240v). These specs avoid the bullshit.
 
You must log in or register to reply here.
Top Back Refresh