Problem with my Quincy 325 compressor.....

I have a Quincy 325 compressor that is giving me some problems.
The compressor began to pop off the safety valve while it was building up pressure. I have had the problem before and it has always been stuck valves.
I pulled the valves and found the inlet side (?) to be pretty dirty and rusty.
The exhaust (?) side was very rusty, dirty and probably not working at all.

I cleaned everything up fully, lapped the flat washers and valve face(s), replaced the copper washers at the base of each. New gaskets, torqued down the valve caps to 50 ft lbs and the set screws to 60 ft lbs. I was certain that it was fixed, as I said, having had this problem before.
The compressor ran fine through about 3 cycles. All of a sudden it began to slow down a bit and start making a terrific mechanical noise at about 125 psi. Very similar to what it sounded like before the valve work, except the pop off valve stays shut.
I just let it run until it shut off at 180 psi.
Same thing happened on the next cycle, so I quickly turned it off and now I am looking for some help on what may be the problem. So, if anyone has some knowledge of the Quincy 325 I am all ears.
The machine was built in 1982. It is powered by a 5 hp Baldor 3ph 220V motor, using straight 3 ph, not a converter. The compressor is only run infrequently and that is the reason the valves get so rusty. Not enough run time to burn off the condensation. Thanks.....pg

I have a couple Quincy 325R compressors like yours. I have found that the guys at Dallas Compressor are pretty good help on the phone. I have also used my digital camera on movie mode with sound and taken a short movie with sound which is like magic in getting service guys help when you go to their shop and show them the movie on the camera display. Much cheaper than having people come for a service call. So far it has been one look and listen to the movie and "oh that is the left hand fornicator gone bad!, we have one right here take off the...and do". Paid for that camera several times over doing the movie routine. The last time I had a problem the fix was to increase the oil pressure by adjusting the screw with lock nut next to the spin on oil filter to get the pressure up high enough to cause the unloader to function, dumb problem, fixed by phone call. I have had a slow speed problem with noise turn out to be a shiny motor pulley caused by a vee belt that had become glazed to the point that it couldn't be tightened enough to not slip and squeal. Replaced belt which looked fine but was shiny after dealer told me it is a common problem on the single belt pulley which is on the newer compressors. Older compressors have two vee belts. I have had problems with single phasing also which trips breaker and has no power but runs the motor when the belt is off.

All of a sudden it began to slow down a bit and start making a terrific mechanical noise at about 125 psi.
I just let it run until it shut off at 180 psi.

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I think you did yourself a great dis-service at that point.
Loud noises in compressors usually signal the time to shut down -ASAP- for through investigation.

With the abundant rust you report, anythings possible at this point. Water in the crank case? Scored cylinder?
Scored crank?

I wouldn't run it anymore until it's completely inspected and the problem is found and corrected.
Quincy parts are not cheap.

dk

Close Work......Thanks for your comment . Good idea about recording the sound on camera.
I am headed over to McKenzie here in Houston this morning to talk to them (again) and see what they have to offer. McKenzie is who built my compressor in 1982 and they are very helpful as well. No problem talking to one of their mechanics and the guys take a real interest in my problem.
Yes, I have noticed a slightly squealing belt at times on mine and it seems to slow down just a bit of course. My motor is a 3ph as I have 3ph service at my house here. The other day I fired it up and it ran without any problem and shut off at 185 psi. I turned the compressor off and walked away.
The following morning I checked the tank pressure and it was 80 psi. So, it leaked out 105 lbs of air overnight and I can guarantee there is no air leaking anywhere in the piping connections. The leak must be back through the compressor somehow. I have heard that can happen before and I have to ask more questions I guess.
I also need to understand the unloader function better than I presently do. McKenzie has a 325 on a stand by the parts counter that has been there for years. It is a cut away display, so I hope to talk with one of the tech guys while standing in front of it......pg

is there a check valve between the tank and the compressor or does it just use the unloaders in the compressor somehow? I've had check valves (especially ones with any aluminum in them) corrode so the unloader was always under pressure resulting in hard or no starting, but I am not familiar with that pump.

t

The leak must be back through the compressor somehow.

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All compressors use some form of one-way valve so that high pressure air flows into the tank from the pump head, but cannot flow back out of the tank. It sounds like your machine may have a check valve or unloader that's going bad. As long as a bubble test shows zero air leakage at the drain, tank outlet, tank inlet, etc., there's only one place left to look ... the check valve or unloader.

Sometimes it's easier to install a Load Genie than it is to buy replacement parts from Quincy. You'll probably find something at this link that will work in your machine ... lot of distributors carry this brand:

http://www.cdivalve.com/products.htm

The check valve in the tank is at the inlet to the tank. It is a passive one way valve that is usually a pretty good one but it has to be. I took one out of a vertical 80 gal. tank that I wanted to use as just a receiver without the check valve. I later found that I had to put some real good sealant around it to stop and air leak that was found with soapy water. Soapy water is the way to find leaks in your piping and they can be pretty subtle but after a while there will be some foam if you have a slow leak. I have a maze of piping and I know I have some small leaks as the compressors start up once in a while to bring pressure back up when there is no intended air use. No leak obvious but I know soap will show some up when I get around to fixing that kind of thing. I called Quincy and they sent me a full set of manuals on the 325R for no charge. Dallas Compressor also has a cut away of a 325R but the manual is better for understanding the theory of operation.

precisionworks said:

All compressors use some form of one-way valve so that high pressure air flows into the tank from the pump head, but cannot flow back out of the tank. It sounds like your machine may have a check valve or unloader that's going bad. As long as a bubble test shows zero air leakage at the drain, tank outlet, tank inlet, etc., there's only one place left to look ... the check valve or unloader.

Sometimes it's easier to install a Load Genie than it is to buy replacement parts from Quincy. You'll probably find something at this link that will work in your machine ... lot of distributors carry this brand:

http://www.cdivalve.com/products.htm

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is there a check valve between the tank and the compressor or does it just use the unloaders in the compressor somehow? I've had check valves (especially ones with any aluminum in them) corrode so the unloader was always under pressure resulting in hard or no starting, but I am not familiar with that pump.
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Nope, not on my Quincy. I was at McKenzie here in Houston today and talking to the service guys and that very question came up. Mine is a Model 325 VD Pilot and there is no check valve between the tank and compressor I was told. So, that settled that.
So I ask the guys 'How in the heck is it leaking 100 lbs of pressure out of the tank overnight, when I know the piping is air tight? I was told that air is leaking out back through the unloaders.
My compressor and motor sit on a stand mounted on a small concrete slab out back of the garage. The 80 gal horizontal tank is inside the garage, along with the on/off and emergency shutdown switches in explosion proof boxes. I have long runs of pipe to the various hose stations to allow condensate to settle out before it hits the first filter set.

My 325 has two diaphram air unloaders positioned a top the intakes on both the LP and HP sides. I took a good look at the 325 cutaway model while I was there, and decided to have a look at my intake valves.
Came home and removed the low pressure side intake valve assembly. The valve looked like I had cleaned it yesterday. No rust at all! I had it apart three years ago and cleaned it then.
Next I pulled the high pressure side intake valve. Very rusty, dirty and almost stuck in place.
So this is what I had found on the exhaust side as well when I took it apart last week. The LP side (exhaust) was fairly clean and the HP side was totally rusted up...........
Question: Why does the high pressure side inlet and exhaust valves get so dirty and rusty while the low pressure side valves are almost to very clean?
I see where I really need to polish the valve washers and the valve(s) seats on the intake valves, as I had done on the exhaust valves last week. So, I will go back to McKenzie tomorrow for another 2 copper base washers for the intake valves and see if it works better.
The compressor has always leaked down a little bit and I have not been able to determine where it leaks. In the beginning there were air leaks at some fittings and filters but a soap water test took care of that. Been 10 years now that I have had this Quincy. I know it is going to run good when I get the intakes taken care of. If not, then I am up a creek. I have no idea of what else it may be.
My compressor is a loadless and will not start to compress until it has oil pump pressure of between 15 to 20 psi approx. Last time I had it running I put a new gage on it and adjusted the pressure to an even 20 lbs. I will post the results of the next session after I get the valves back in.
Thanks again for your comments Tomjelly.
Thanks for yours as well Precisionworks. As I said at the beginning, the compressor has no check valve, but rather two air unloaders. One of the service guys told me to fill the tank with air and then remove the inlet filter and stick a pipe plug in the inlet pipe. If it held air overnight then the air is leaking back through the inlet valves......or at least that is what I thought he said, but not entirely sure to tell the truth.
If you can explain to me how the air unloaders work, I am all ears!!! I really do not understand their operation in detail and that would be nice to hear an explanation.
Thanks guys..........pg

Quincy Compressor

I had a similar issue which happened only once in awhile, then more ofter. Checked all the usual places and all appeared OK. In my case it turned out to be low oil pressure. I had forgotten to check the oil level, and it was low. The safety was keeping the unloader open and not allowing the compressor to build pressure.

No check valves on 325 alot of times because the HP exhaust valve is good enough to act as a check valve.

HP valve rust is caused by condensation from the LP compression. This could be a problem associated with short runs on the pump. Like if you were to run the air compressor for 5 minutes at a time. HP side could get wet and then never get hot enough to rid itself of the moisture from compression.

Unloader on the 325 is oil pressure controlled. No oil pressure, head unloaded. OK, so you start compressor, it builds oil pressure (pressure lubed system) and a crankcase valve is opened allowing tank pressure to the top of the unloader(s) mounted on the top of the head. This pressure then loads the valve(s) on your pump.

Built in head unloaders work in different ways. The photo below is a Champion pump with centrifugal unloader (#13 ). The unloader stays in the open position until the crankshaft reaches a speed that causes the unloader to close. Much like the centrifugal switch in a capacitor start electric motor - the capacitor is connected until the shaft reaches a certain speed.

Barry, the real caveat with the Champion system (and most others) is that the pump will pump with or without oil until there is a mechanical failure. This is not true with the Quincy pressure lubed unloader. It will not load the pump anytime there is loss of oil pressure.

Your compressor set up sounds a bit like mine, FWIW I put a soft seat check valve after the air cooler and get no leak down, before doing so it was quite bad.

Any leak from the high pressure discharge valve will be a problem with regard to the system holding pressure overnight, once air gets past this valve it leaks past the rings.

Diaphragm unloaders work by holding open the inlet valves, I have never seen oil operated unloaders, always air or electrically activated air. Make sure the unloader is adjusted properly in that it only contacts the inlet valve when pressure is applied to it's diaphragm.

As for the corrosion in the high pressure inlet, this is normal, I used to have a 3 stage compresser and it would drop plenty of water between stage 2 and 3 (400 psi), fixed it by installing a water seperator between stages.

HelicalCut said:

Your compressor set up sounds a bit like mine, FWIW I put a soft seat check valve after the air cooler and get no leak down, before doing so it was quite bad.

Any leak from the high pressure discharge valve will be a problem with regard to the system holding pressure overnight, once air gets past this valve it leaks past the rings.

Diaphragm unloaders work by holding open the inlet valves, I have never seen oil operated unloaders, always air or electrically activated air. Make sure the unloader is adjusted properly in that it only contacts the inlet valve when pressure is applied to it's diaphragm.

As for the corrosion in the high pressure inlet, this is normal, I used to have a 3 stage compresser and it would drop plenty of water between stage 2 and 3 (400 psi), fixed it by installing a water seperator between stages.

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Well, I found out today that what I had stated previously, saying I have a 325 VD Pilot, is incorrect.
Instead, what I have is a 325 with a hydraulic unloader and two air unloaders mounted above each intake on the head.
When I turn on the compressor there is air pressure from the air tank present at the closed hydraulic unloader. The compressor begins to rotate and this is starting without a load on it.
When the oil pressure reaches 20 psi, a gate inside the hydraulic unloader is moved to open the unloader. This allows the air to flow to the air unloaders above.
I have attached links to 2 photos that show my machine without the intake valves in place. The close up is of the hydraulic unloader.
I had a big cleaning job on the high pressure intake valve and related parts today. Tomorrow I expect to finish it and then I shall see if I was successful or not in getting things working again. Thanks for the comments from all of you guys..........pg

I managed to get things cleaned up and put the compressor back together tonight. All was fine for a while, but then things turned sour.
Here is a pic of what the parts looked like right out of the compressor without cleaning anything.



The Low Pressure intake valve and related parts are very clean, considering it has been 6 years since it was last opened.



Such was not the case with the High Pressure intake valve however. Very rusty and it needed a complete cleaning.



Anyway, I got it all back together tonight. Here is a shot showing the hydraulic unloader down on the front of the crankcase with the air tube going up to the air unloaders at the top. The LP unloader is connected to the HP unloader and the other side of the HP tee is plugged.






So, what happened when I started it up? It ran quiet and perfect. The pressure built up to 170 psi and I was ready for it to shut off at 185. Well, at that point the mechanical noise began again. Just barely at first, then it quickly became louder and louder and the speed seemed to slow down. It sounded like the noise was coming from the compressor pulley itself! I ran into the garage and shut the compressor down, catching the end of an aluminum ladder as I rounded the corner at flank speed in the dark that was hanging alongside the garage. I got a nice black eye from that one!

I guess tomorrow I will pull the belt cover off and check the torque on the pulley bolts. They should be at 70 ft lbs.
Otherwise, I am at a complete loss as to what my problem may be. I feel that the insides of the valves are in good shape, and the compressor sounds as good as the day I got it except for that mechanical noise that appears just before it shuts down.........pg

maybe its always been making that near the end of cycle noise and you never noticed it because the machine is outside?? May want to double check the motor and pump mounting bolts too as well as the mounting to the ground as if anything is loose it will hammer away...I really like that quincy design, I priced a new pump alone and it was too expensive so i'm hoping to find a used one someday...

t

tomjelly said:

maybe its always been making that near the end of cycle noise and you never noticed it because the machine is outside?? May want to double check the motor and pump mounting bolts too as well as the mounting to the ground as if anything is loose it will hammer away...I really like that quincy design, I priced a new pump alone and it was too expensive so i'm hoping to find a used one someday...

t

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The noise is something that should not be there. It is outside, but I know the compressor and how it runs....this clanging is something new. When I reworked the discharge valve side of things 2 weeks back, the machine ran fine for a couple of days and I had decided just to leave it on all the time so that more running might prevent the rust. Well, I suddenly heard it inside the house (where I never can hear it running) and going out back it was just clanging away. I will just have to keep after it until I get the problem zeroed in.

Yes, the Quincy is as fine a compressor as I have ever seen. I paid a lot for mine. A very large price indeed, but now I have no regrets and am thankful to have it, even if it is somewhat broken at present.

There is a Quincy on Ebay right now. The guy had ran the ad for a couple of weeks and now has a BUY IT NOW price of $2500. That is still a lot of scratch, but they are nice machines. You buy one and take care of it and it will outlive you. Ebay #190110698640.......pg