Compressor clunking / rattling while running: need diagnostic / repair help

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tmassey

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The day that all compressor owners fear has come: my compressor broke. I don't where to go next.

I set up to run it today as normal and pressed the button. The compressor sprung to life, sounding just like it's supposed to. It made its way up to 2000 PSI and gas started coming out of the hose, just like it's supposed to. But as the pressure built up from there, it soon started making consistent clunking/rattling noises. This happened within a few minutes of starting: probably 5 minutes or so of running.

I looked everything over for about 60 seconds or so. I couldn't pinpoint the noise, but it sounded like it was coming from the compressor head. Nothing was visibly slapping or wiggling (like, say, a belt striking something), so I shut it down. I drained all of the pressure down and started it back up: the clunking noises started from the very beginning. I took a 5 second video of it so you can share in my misery and shut it back down again.

So, now what do I do? I have zero knowledge about compressor repair, and a rather large amount of intimidation to try. Of course, if it's broken it does me no good, so that helps to get over the intimidation. But that still leaves me with exactly zero idea of what to look at, what to diagnose or even what to try.

Here's a link to that video so you can hear it along with me.


With my ear protection on it sounded a lot less like a rattle and a lot more like regular clunking. But either way, something is not right. While it was running I glanced at the pressure gauges: they were at 80 PSI, 400 PSI and 2500 PSI, which is where I expect them to be at that point. The oil is at the right level (which I always check before I start). It's over 60 degrees out today, so plenty warm.

Compressor details: Poseidon PFU-150: 6CFM, three-stage, 5000 PSI compressor with a 5HP single-phase electric motor. It's kinda-sorta a Bauer block. It *is* a block made by Bauer, but it's a different block than used in the normal Bauer-branded compressors. The third stage is the one with a "hole" in it -- if you've seen a Poseidon block you'll know what I'm talking about. In principle it's the same as any other similarly-sized compressor and in practice it uses many Bauer parts. It even looks a lot like a Bauer, but it's not identical.

I'm officially out of ideas! I would be grateful for any suggestions you might be able to make.
 

rob.mwpropane

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I don't have anything to add to help, but very sorry for your situation. Not a spot any of us want to be in, fingers crossed it's something minor.
 

-JD-

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First thing I would do is check to see if one of the pulleys is loose on a shaft. How hard is it to slack the belts on that setup?
 

Tracy

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I can help you with it when I get back from Florida. You need a compressor to borrow til this one is fixed? I have a couple of spares.
 

Wookie

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The day that all compressor owners fear has come: my compressor broke. I don't where to go next.

I set up to run it today as normal and pressed the button. The compressor sprung to life, sounding just like it's supposed to. It made its way up to 2000 PSI and gas started coming out of the hose, just like it's supposed to. But as the pressure built up from there, it soon started making consistent clunking/rattling noises. This happened within a few minutes of starting: probably 5 minutes or so of running.

I looked everything over for about 60 seconds or so. I couldn't pinpoint the noise, but it sounded like it was coming from the compressor head. Nothing was visibly slapping or wiggling (like, say, a belt striking something), so I shut it down. I drained all of the pressure down and started it back up: the clunking noises started from the very beginning. I took a 5 second video of it so you can share in my misery and shut it back down again.

So, now what do I do? I have zero knowledge about compressor repair, and a rather large amount of intimidation to try. Of course, if it's broken it does me no good, so that helps to get over the intimidation. But that still leaves me with exactly zero idea of what to look at, what to diagnose or even what to try.

Here's a link to that video so you can hear it along with me.


With my ear protection on it sounded a lot less like a rattle and a lot more like regular clunking. But either way, something is not right. While it was running I glanced at the pressure gauges: they were at 80 PSI, 400 PSI and 2500 PSI, which is where I expect them to be at that point. The oil is at the right level (which I always check before I start). It's over 60 degrees out today, so plenty warm.

Compressor details: Poseidon PFU-150: 6CFM, three-stage, 5000 PSI compressor with a 5HP single-phase electric motor. It's kinda-sorta a Bauer block. It *is* a block made by Bauer, but it's a different block than used in the normal Bauer-branded compressors. The third stage is the one with a "hole" in it -- if you've seen a Poseidon block you'll know what I'm talking about. In principle it's the same as any other similarly-sized compressor and in practice it uses many Bauer parts. It even looks a lot like a Bauer, but it's not identical.

I'm officially out of ideas! I would be grateful for any suggestions you might be able to make.
Did it continue to build pressure? My guess is you carried away a valve. Which may be in the top of the jug and is beating the hell out of the piston top.
 

Rol diy

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Sure sounds like a pulley is loose on the shaft or something, but I know with videos the sound is never as good as standing there,


Better have someone that's got an idea listen and look at it before you rip the compressor its self apart,
 

Namreg 58

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Either one of your final stage valves is leaking or a condensate drain seat is shot. Let the compressor build pressure and switch it off and spray soapy water around final separator and filter housing to determine possible leaks. It sounds like floating piston rattle to me.

Could also be a malfunctioning solenoid on the ACD
 
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tmassey

tmassey

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Thank you for your replies! Here's my information:

First thing I would do is check to see if one of the pulleys is loose on a shaft. How hard is it to slack the belts on that setup?

Sure sounds like a pulley is loose on the shaft or something, but I know with videos the sound is never as good as standing there,

Both the compressor head flywheel and electric motor pulley are solidly attached to their shafts: no play whatsoever, either on the shaft or along the direction of rotation.

Did it continue to build pressure? My guess is you carried away a valve. Which may be in the top of the jug and is beating the hell out of the piston top.

Either one of your final stage valves is leaking or a condensate drain seat is shot. Let the compressor build pressure and switch it off and spray soapy water around final separator and filter housing to determine possible leaks. It sounds like floating piston rattle to me.

Could also be a malfunctioning solenoid on the ACD

There is no ACD on this compressor. No solenoid, and all three drain valves were tight and not leaking. I'm not sure whether it will *build* pressure or not: once it started rattling I did not let it run long enough to see if it would continue to build pressure -- mainly because I had the same thought that something inside was loose and beating my compressor to death from the inside! :)

The idea of it being a final stage valve is a common one. I spoke with @Tracy last night who walked me through a couple of diagnostic items. Here's a log of what I've done so far, with some photos.

First, I removed the belt from the compressor/motor. I then spun the flywheel by hand (counter-clockwise, so the fan is blowing against the compressor) slowly. I felt no catches or hesitations, and heard no scrapes or rattles. The only thing I felt was a gentle and linear increase and then decrease in resistance (I assume as a cylinder goes through its compression stroke), and a quiet "hoo hoo hoo" as it sucks air into the first stage. Supposedly this is good news, because if it were a bearing inside of the compressor I should be able to feel it. (Which might just be giving me too much credit for sensitivity: what do I know...)

Next, Tracy convinced me to take the head off of the third stage. First, after loosening the screws and intake/exhaust tubes, right before removing the cap:

IMG_0122-small.png


Next: after removing the screws and cap, which is just a relatively thin plate of metal. It leaves behind what I'm calling the 'valve puck':

IMG_0123-small.png


If you're curious, the wired item is the over-temperature shutoff.

From the research I've done, it seems that the black bolt-looking thing slightly offset from the center is the final stage discharge valve. I believe it is this: Bauer Final Stage Discharge Valve 014121 - August Industries Inc.

Next, once I got the intake/exhaust tubes off, the puck came free of the cylinder. This is the under-side of the puck, the part that is directly on top of the cylinder and piston:

IMG_0125-small.png


I believe that the final stage intake valve is visible near the center: the black item with the six small holes in a circle. Again, I believe it is this: Bauer Final Stage Intake Valve 081409 - August Industries Inc.

Here is a photo of the cylinder and piston with the valve puck removed:

IMG_0126-small.png


I used my pinkie to push the piston down about an inch or so: that's as far as my fat digit would go. It pushed down easily. I then rotated the flywheel and the piston moved up smoothly and quietly. I saw no debris or anything anywhere, though it's not impossible it might have fallen out when I loosened the puck: I didn't know it wasn't actually attached and wasn't expecting it to come loose exactly when it did.

Tracy asked me to try to blow through / suck from the intake and exhaust ports on the valve puck. When I do, no gas moves in either direction from either port. In some cases "no gas" means just that: I can suck a hard vacuum on the intake port (which is exactly what it should do). Other times it means extremely little gas: on the exhaust port I can suck a weak vacuum that lasts for a second or two. It's not exactly "no gas", but it's pretty close, seeing as there should be relatively minimal resistance in that direction.

It seems odd that I would have *two* failed check valves at the same time, so I'm suspicious that I'm simply doing something wrong.

Earlier Tracy had stated that the intake valve could be removed by using something like snap-ring pliers to unscrew it from the puck. I tried with a moderate amount of force but it would not budge, so I did not push the issue. The same is true of the exhaust valve: I used a wrench with moderate force on the flats of the valve but it did not move, and I do not want to risk making this worse.

So, I'm at the end of the diagnostic steps I was given. I'm not sure where to go from here. I'm open to further thoughts or suggestions. If there are things you'd like to see or for me to try (or re-try: you won't hurt my feelings!), please let me know. If you have any detailed information on how to check or remove those valves, I would be very grateful as well.

Oh, and @rob.mwpropane , thanks for your sympathy! :)
 

Rol diy

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Not sure but can it run with the head off?

Have you run the electric motor with it disconnected?
Seem strange it's making noise now and
Didn't start last time you used it,

I want to say its something simple, just from the sounds off it, but keep eliminating things,

My small baur makes a terrible racket when I am under 500 psi, it became the hp piston is not pushed against the driven piston,,, I think the bigger ones have oil between the 2 pistions
 

Wookie

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Not sure but can it run with the head off?
NO!!!
My small baur makes a terrible racket when I am under 500 psi, it became the hp piston is not pushed against the driven piston,,, I think the bigger ones have oil between the 2 pistions
No, the larger ones (and newer ones) do not have a floating piston.
Other times it means extremely little gas: on the exhaust port I can suck a weak vacuum that lasts for a second or two. It's not exactly "no gas", but it's pretty close, seeing as there should be relatively minimal resistance in that direction.
You should never have any leak by of any amount sucking on a set of valves. If you do, and it’s minor, you have dirty valves. Little chunk of carbon.
 
https://www.shearwater.com/products/swift/

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