Need Air Compressor Help

[gm280]

Okay, I am hoping that someone in iboat land has an answer or has come across this situation. Here goes...

I have a 1995 4.5HP (yeah right) 115 volt 20 gallon Campbell Hausfeld air compressor. And until about two months ago it worked perfect and did everything I asked of it.

Then one day it was running and started running slow and slower and almost stopped before I unplugged it. Instantly I thought about either the run capacitor or starting cap finely gave up. I read them via a Fluke cap meter and the run cap was just a little low. It read 25.7mfd instead of 30mfd. The start cap was in the range listed on the cap. But I bought both new and installed them... No difference and the start cap literally exploded and it was good it was inside the cap metal cap tank on the outside of the motor to contain all the exploded parts. After the explosion and smoke cleared, I decided to remove the motor and check it out. After removing the motor end, part of the centrifugal electrical switch fell out. It was broke and was not cutting out the start cap, which blew up. So I tried, unsuccessfully, to JB weld the plastic switch and same results...it runs 'til about 25psi and starts running slow, and slower till I unplug again.

So I just ordered a new 2HP motor and installed it. Two HP is what is on the original motor spec tag and the current draw confirms that. Exact same problem. Absolutely no difference with the new motor. Next I bought a new pressure switch and installed. No change, same problem. Getting frustrated, I ordered all new pump gaskets and reeds and reed plate. Installed everything and absolutely no difference. Same slow running. So I removed the one way tank check valve guts so the compressor pump was not fighting the one way valve... Absolutely same, runs to about 25psi and then starts running slow and slower and slower 'til I unplug it again. I checked the tube from the head of the pump to the tank and the tube from the one way valve to the pressure unloader valve that opens to bleed air after it shuts off, and made sure they were open. Same problem!

I thought about blow by in the pump piston rings and it pressurizing the splash oil gally. but since the dip stick is merely pushed in, I though if that were so, it would blow the stick out. And once it runs slow and the tank reads ~25psi, I can stop it and manually bleed off the unloader valve and no air comes out and if I plug it back in, it runs really slow instantly...

I have absolutely no idea what to do next. Oh, the tank has been drained many, many times over the years, included during all this time as well...

 

[dingbat]

Check the supply voltage while it’s running. Pretty typical behavior when the voltage is sagging.

Works ok until you build up resistance (pressure) and the thermal overload kicks out

 

[gm280]

Check the supply voltage while it’s running. Pretty typical behavior when the voltage is sagging.

Works ok until you build up resistance (pressure) and the thermal overload kicks out

I will check it, but pretty sure it is okay since I moved the air compressor around to three different circuits all by itself. But I will put a volt meter on it for sure... I keep thinking piston ring problems, but I would think if either ring blow by or rings worn out it would continue running with out building much pressure. But I don't think it would make the compressor run slow and near stop... IDK!

 

[Scott Danforth]

Check the contacts in the pressure switch. They get old and pitted from arc flashes. Some times they stick and the compressor will run past the switch point and load up the motor. You can run a points file thru them. However after 30 years, that $18 switch probably needs replacement

 

[dingbat]

I will check it, but pretty sure it is okay since I moved the air compressor around to three different circuits all by itself. But I will put a volt meter on it for sure... I keep thinking piston ring problems, but I would think if either ring blow by or rings worn out it would continue running with out building much pressure. But I don't think it would make the compressor run slow and near stop... IDK!

They normally start throwing oil long before you have pressure issues.

Be sure to check the power from source to motor. Could be a compromised wire or connector in the power circuit. A 2hp motor needs a dedicated 20 amp circuit

My compressor at the barn was doing the exact same thing. Checked unloader, pressure switch, belt tension, ect…... nothing.

By this time I had spent 45 minutes messing with the system. Had to be the motor….

Tore belt guard and took belts off. Couldn’t reach the back motor bolt so I pulled my roller box away from the wall to gain better access. Found compressor plug just barely in the wall socket. Felt like an idiot as I put everything back together.

 

[gm280]

Check the contacts in the pressure switch. They get old and pitted from arc flashes. Some times they stick and the compressor will run past the switch point and load up the motor. You can run a points file thru them. However after 30 years, that $18 switch probably needs replacement

Actually I did think about that. And after seeing the serious pitting, I bought a new one and installed. But I also took the old one and took it apart to file those contacts back to like new. I guess I could use it for a backup...if ever. So the contactors, cut out/in and unloader valve are ll new presently. But thanks very much for the suggestion.

 

[gm280]

They normally start throwing oil long before you have pressure issues.

Be sure to check the power from source to motor. Could be a compromised wire or connector in the power circuit. A 2hp motor needs a dedicated 20 amp circuit

My compressor at the barn was doing the exact same thing. Checked unloader, pressure switch, belt tension, ect…... nothing.

By this time I had spent 45 minutes messing with the system. Had to be the motor….

Tore belt guard and took belts off. Couldn’t reach the back motor bolt so I pulled my roller box away from the wall to gain better access. Found compressor plug just barely in the wall socket. Felt like an idiot as I put everything back together.

Amazingly when I installed all new gaskets and reed plate, the cylinders still had faint crosshatch on them. I thought that was interesting after near 30 years of work. Also, thanks for the suggestions and response. I do appreciate it.

 

[Scott Danforth]

only reason I mentioned the switch, mine welded themselves on, and one day, the compressor was laboring. I unplugged it, and noted I have 175psi in the tank (145psi safety valve didnt blow)

so now I have a new switch, unloader, safety, etc.

check line voltage when the compressor is running

 

[bwkre]

New motor matches the old for rpm? probably 3450, almost all small compressors are.
Is it a twin cylinder , single stage or 2 cylinder , 2 stage?
Almost sounds like the compressor is seizing. Time appox how long it takes to get from an empty tank to when the issue occurs. Then attach a blow gun or leave the hose end open and test it again. It probably won't reach 25 psi. If it slows again you could have a crank issue.
You could also try removing the belt guard, run it till it starts to fault. Unplug it, bleed the head pressure and try to move the crank pulley by hand. It should move fairly easy till you start to make compression in the head. Back & forth should tell you if its free. Hands best kept on the outside of the crank pulley where the belt rides, dont want to crunch any fingers.

 

[alldodge]

When it slows is the plug or wire getting warm/hot?

 

[gm280]

New motor matches the old for rpm? probably 3450, almost all small compressors are.
Is it a twin cylinder , single stage or 2 cylinder , 2 stage?
Almost sounds like the compressor is seizing. Time appox how long it takes to get from an empty tank to when the issue occurs. Then attach a blow gun or leave the hose end open and test it again. It probably won't reach 25 psi. If it slows again you could have a crank issue.
You could also try removing the belt guard, run it till it starts to fault. Unplug it, bleed the head pressure and try to move the crank pulley by hand. It should move fairly easy till you start to make compression in the head. Back & forth should tell you if its free. Hands best kept on the outside of the crank pulley where the belt rides, dont want to crunch any fingers.

Okay, let me take each suggestion as you wrote them. First, thanks very much for the reply and suggestions. I honestly appreciate everyone that comes up with any idea.
It is a twin cylinder quality cast iron setup but single stage. Not double stage.
When I start from an empty tank it only takes about a minute to go to ~25psi. And once it approaches that pressure, it labors seriously hard to the point that I unplug it to keep from burning up the new motor. The motor speed is 3450rpms. And once I unplug it, I can easily turn the flywheel/pump pulley easily. So there doesn't seem to be a stopped up pump. I can also disconnect the pump from the tank and it will run without any issues. So the 25psi is enough to lug the motor down to almost stop. Presently I have the guard off to try different ideas.
I am going this morning to test both the voltage and current at the motor. Both motors, the old one and new one, do the exact same thing at the exact same psi pressure...
Never thought about the cord itself. And since it is near 30 years old, I should have checked that already. But since the motor runs great initially, I didn't think about it... That's what I get for assuming...

 

[gm280]

When it slows is the plug or wire getting warm/hot?

The plug isn't warm, but I haven't felt the cord itself. I will do that as well as the voltage and current tests at the motor... Thanks for the idea.

 

[gm280]

Okay everyone, I first need to thank each and everyone that offered ideas, suggestions and things to check. And I did everyone of those ideas as well. However, I am here to say I got it fixed and the stupidity of me was the fault all along.

I noticed every time I tried to make it work, it basically stopped at around 25psi. So I instantly unplugged the cord. But I also noticed that the pulley end of the motor was very hot to nearly can't touch it. And since the motor is a new "2hp AC induction motor", it has no voltage connections whatsoever to the armature. And that puzzled be for a while... Well I just tried again and monitored the AC voltage at the motor's AC input. The voltage never ever changed even when it slowed to almost stop...again. So I drained off the ~25psi and did it again. But this time I watched the pulley side very closely. What I noticed is that when it slowed the large pulley on the motor almost stopped, but the small motor pulley was spinning away...
So I thought, could this be a too loose of a belt? I loosened the motor and slide it at tight as I could while retightening the bolts and nuts.
Would you believe it filled up without a hitch all the way to cutout at about 130psi...
All this time it was the belt not tight enough and I didn't even notice it. I thought about a new belt, but now I will replace that one with a fresh one and be a totally happy camper once again.

Thanks everyone. I really wanted to post the fix and my utter stupidity so everyone could shake their heads in such ignorance I displayed...

Have a great day boaters!

 

[topgun3690]

It's a good feeling when you fix something that is broke......good job. I had the same unit until a few years ago......was working fine but replaced it as the tank was getting pretty corroded/rusty.....was afraid it was gonna "blow"....lol.

 

[Scott Danforth]

glad you found it.

 

[gm280]

Just for a little more update. This 29 year old compressor sits in my shop and there is absolutely zero rust or corrosion on it anywhere. With the exception of the large faded Campbell Hausfeld decal on the side of the tank, you would probably never be able to tell how old it is. It looks maybe a couple years old at best... Nice to have it back running again. My air compressor is without a doubt the most used tool in my shop. Never would have thought so until I was without it for a few weeks.

When something like that stops working, it seriously bothers me until I finely fix it and know absolutely what was the problem... Just my OCD I guess...If I actually have that?

 

[Scott Danforth]

if you truly have CDO, you would re-arrange the letters

 

[Scott06]

Check the contacts in the pressure switch. They get old and pitted from arc flashes. Some times they stick and the compressor will run past the switch point and load up the motor. You can run a points file thru them. However after 30 years, that $18 switch probably needs replacement

This wont be getting full voltage to motor downstream of pressure switch. Plugging it in to multiple outlets wont fix that

 

[gm280]

This wont be getting full voltage to motor downstream of pressure switch. Plugging it in to multiple outlets wont fix that

I totally appreciate your response and concern, but everything is now up and running perfectly again. And I did take the contactor (pressure switch) and filed those contacts to like new again, but I replaced the entire unit, since that is how you buy them, anyways. 30 years was a long time for them to work, so I gave them a retirement plan now. And it is great to have everything back to working again. I also bought a new centrifugal switch plate and the old motor runs like new now as well... All is great in the end!