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Ridgid Air Compressor Problem- not building pressure. At all.

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  • Ridgid Air Compressor Problem- not building pressure. At all.

    So I picked up this used Ridgid air compressor for a song, but it needs some help.
    It's the Oil Free 45150A, twin stack 1.8hp
    Previous owner says, "yeah it runs, it just doesn't build pressure past 80lbs, so it never shuts itself off."

    No big deal I say, so I bought it ($25) and promptly order a replacement piston and put it in. Sure enough, when I disassemble it, the old piston fell right out, the "rings" were worn out. Feeling pretty smug, I put it all back together, tighten up the bolts and fire it up.

    It runs smooth, quiet, and doesn't build a pound of pressure. I took it apart a couple more times to make sure I didn't put something in backwards, but no dice. Where'd I screw up?

  • #2
    Re: Ridgid Air Compressor Problem- not building pressure. At all.

    Could be any number of places depending on how much disassembly you did. I am surprised that the old rings were worn out so quickly; did the previous owner give you any indication of how many hours he had on this? It just seems too new to have worn out the piston rings, even for an oil-less unit.

    But to the problem: Did you disassemble the valve plate and if so is it possible that you got it in wrong? If the valves (not looking at the exploded view, I believe these are reed-like valves) are not correct, or dirty then you are not capturing the air in the cylinder... thus the air simply goes in and comes out with NO compression.

    I presume the piston rings were installed correctly and you have a nice seal against the cylnder wall. Are these 0-rings or some kind of teflon-impregnated split ring... if the latter, the "splits" between one ring and the other should not be aligned (again, I'm not looking at any illustration, so I have no idea the number or type of rings in use).

    Have you checked of leaks around the cylinder, the outlet tube and is th check vavle working... and with the drain valve on the tank open, are you getting any exhausted air indicating that at least there is "compression" coming from the running air pump?

    Off the top, that is about the first things that I would check,



    • #3
      Re: Ridgid Air Compressor Problem- not building pressure. At all.

      So..... from what I recall (it's been a few weeks since I played with this thing- got a bit frustrated).....
      The "rings" are single synthetic leather type material, so no splits to line up- it's fixed into the piston itself.

      I did disassemble the valve plate, but there were distinct enough impressions on it that I was able to reinstall it correctly. I still doubted myself, so I tried it both ways until I was confident I got it correct.

      How would be the best way to check for leaks around the cylinder? There's a lot of air moving from the cooling fan, so it's tough to simply "feel it".

      I believe the cylinder is pumping air- I disconnected the line that runs from the cylinder to the tank and it blows air when the compressor is running.

      How would I test the check valve? I have not tested running it with the drain valve open.


      • #4
        Re: Ridgid Air Compressor Problem- not building pressure. At all.

        So I threw it up on the bench again this afternoon and here's a few more details I forgot:

        Neither of the gauges work, so that doesn't help me read pressure anywhere.
        No leaks around cylinder or valve head (checked by spraying with liquid lube to look for bubbles)
        Does build some pressure in tank after about 5 minutes of runtime. Like 10-15lbs. Drains quick.


        • #5
          Re: Ridgid Air Compressor Problem- not building pressure. At all.

          Sorry I haven't been able to reply... I'll try to get something back later this evening.

          But, this thing sounds like it was really abused, with BOTH gauges damaged and not working. Fortunately gauges are relatively inexpensive.

          So, the pump is at least putting air into the tank... just that the pressure doesn't seem to rise, if I'm reading you correctly. Off-hand, there would then have to be a leak in the tank, but not that you've found... or the output from the compressor pump is so little that it cannot overcome the pressure already built up in the tank???

          To quickly answer the "check valve" question of yesterday: At the point where the air line comes from the cylinder outlet and enters the tank, there is a check valve (usually mounted on/in the tank at that point). A check valve is basically a one-way valve... allowing air to pass into the tank, but not back out. The pressure from the line actuates the valve open and when that pressure stops (compressor shutoff) the inner tank pressure snaps the valve closed, thus retaining whatever pressure was built up in the tank. The tank pressure is then reduced by either using it, or by opening the condensate drain valve. Therefore, if the tank pressure falls by itself, then there is either a leak in the tank (very rarely the case), a leak in the drain valve (quite often the case), by air leaking around the tank gauge connection (rare, put possible) or by air leaking back through the check valve (rarely the case).

          If air IS leaking back through the check valve, then it may re-pressurize the cylinder, in which case the compressor would probably not automatically start because of the load (pressure) against the piston... and the circuit breaker would trip. But, in your case there doesn't seem to be enough pressure building to even cause that problem.

          More later,



          • #6
            Re: Ridgid Air Compressor Problem- not building pressure. At all.

            Okay, I don't see any further posts from you so I figure you've either set this aside or whatever. Check out the steps on my previous post.

            There are not many places on the tank itself that will leak. (I use "bubble" soap to check leaks; you know that stuff kids blow bubbles with.) Connections on the tank amount to drain valve at the bottom, check valve connection at the top, and where the Pressure Switch mounts via a pipe nipple, which should also be at the top. In my experience, the most often place for slow leaks is debris which has lodged itself in the condensate drain valve.

            On the Pressure Switch itself, there is what I term a connection block... which has four outlets, all of them the same pressure: one is for the Tank Pressure Gauge, a second for the over-pressure Safety Valve, a third for the Air Manifold (or outlet piping assembly) to the adjustable Regulator, and whatever connection apparatus utilized (quick connect, etc.), and the 4th is the nipple connection between the Pressure Switch and the Tank. Any of these pipe threaded connections could be leaking and thus cause the Tank to drain rapidly.

            Okay, so any of those connections would cause a slow leak. But, not so much that the tank will not pressurize at all. Any of these leaks would allow the tank pressure to build, but then drain fairly rapidly depending on how bad the leak is. However, if the condensate drain valve is totally clogged, or somehow lodged open, you would probably never attain any kind of main pressure build.

            To review the whole issue, you must be assured that the compressor is in fact pumping air. If it is not, then you either have a serious valve problem (like they're not seated or not oriented correctly) or you have a serious piston/ring problem and you're getting blow-by past the rings and thus no compression.

            Off the cylinder head, there is a inlet connection to which a filter should be attached (keep it clean and in place). Opposite side of that cylineder head should be the outlet connection... make sure that fitting is properly tight and there is no leaks there. That tube (might be a braided hose), runs from the cylinder head to Check Valve which is mounted on the tank. The Check Valve allows air to flow only one way... into the tank.

            On most (if not all) modern small compressors, this Check Valve is actually a "T" with another pipe or tube running over to the Unloader (also sometimes termed "Release") Valve which is mounted on the back of the Pressure Switch. When the Pressure Switch senses that the tank has reached its maximum operating pressure, the Pressure Switch will simultaneously shut off the motor and activate this Unloader Valve which will dump the air between the tank Check Valve and the Cylinder Head, thus relieving all pressure in both the Cylinder and the Check Valve and the Unloader Valve. This allows the motor to restart without any pressure load. Remember, that the Check Valve allows air to pass only one way (into the tank), so when the Unloader Valve dumps the air in the line, no air should come back from the tank to re-pressure that line and cylinder.

            Often reported, is trouble that the compressor will not start after it's initial use, and when the pressure drops because of use. (In other words, the compressor will not "re-cycle"!). This may even cause a circuit breaker to trip. While this can occur on initial start, where it may be an extension cord (too much electrical resistance and therefore not enough Amps) or high oil-viscosity (like cold weather does effect "lubricated" compressors), it can be because the "Unloader Valve" has failed to dump the air from cylinder... thus the compressor overloaded because it can't turn-over against the pressure existing in the cylinder.

            I hope this helps,

            Last edited by CWSmith; 07-24-2012, 06:32 PM. Reason: Added paragraph concerning Unloader Valve failure


            • #7
              Re: Ridgid Air Compressor Problem- not building pressure. At all.

              Nope, I haven't shelved it just yet.....

              Your post was super helpful, it allowed me to narrow down what my issues are.

              To my knowledge, the pressure switch and associated fittings hold air. At least to 50 lbs, because that's what it held when I bought it. That was all the higher it would pump to at that time. I also cannot hear it leaking when the pump is off. You're also right in that it has to be in the compression/pumping system, not in the retaining pressure.

              So.....those things connected- my problem has to be something I've touched- piston, cylinder, or head and associated fittings.

              I think I'm probably going to bite the bullet and order the valve head kit for $50 and get it done. The $65 I already have into this thing is sort of water under the bridge at this point, so if I can have a working compressor for $50, I'd be good with that.

              It may be a bit before I get the parts and get this thing back together, but I'll keep tabs on this thread and I'll make sure to post a final wrap or next step to put closure to this for anyone else's reference.

              Thanks CWS, that's exactly what I needed- Much appreciated


              • #8
                Re: Ridgid Air Compressor Problem- not building pressure. At all.

                You are welcome, I'm glad that I could provide some help.

                You didn't mention what this compressor was going to be used for, and I'm hoping that this thing will meet your purposes with all the investment in time and money. But of course there is some good value in just doing this work and the gains in that experience.

                Let me know if I can be of further assistance.

                Wishing you good fortune and success,



                • #9
                  Re: Ridgid Air Compressor Problem- not building pressure. At all.

                  reading through what was gone over here and working with compressors, my gut feeling is a gasket in the head. It probably has a crack or a piece missing and its leaking between the inlet and exhaust ports. Unless the reed valves were messed with and no seating I don't think they would be the issue. The cup seal on the piston is probably fine, unless this unit has be run a lot. But since you replace it and i assume the cylinder that should be fine too. Was the cylinder scored at all when you first looked at it?

                  to tell if your problem is in the cylinder head or further down the line, try this. remove the intake filter and put you finger over it. is the suction really good? if no most likely in the head. if it is pushing any air out the intake its in the head. if you can't tell, try this. Put your finger over the exhaust port on the cylinder head. you should not be able to hold back all the pressure the compressor make. if you can hold back the pressure the problem is in the head.

                  It should take 5 minutes for the compressor to fill the take to 150 PSI.

                  if the head checks out as I suggested above, then you have to look for a leak, it should be a pretty big one. Soup not needed to feel it.


                  • #10
                    Re: Ridgid Air Compressor Problem- not building pressure. At all.

                    So here's where I arrived at-
                    I couldn't bring myself to pay an arm and a leg for more gaskets, so I just picked up some raw gasket material from Napa and traced and cut a new gasket for one or two of the gaskets I was short.
                    Helped a little bit, got er to pump up to about 30 psi in 5 minutes.

                    That's where I put the project on hold- I didn't really want to keep throwing cash at this thing without knowing what was wrong with it.
                    So I put an ad up on Craigslist to try to recoup some of my expenses - $40. In the meanwhile, I picked up a nice used Craftsman 20 gallon oil lubed unit, 3hp for $100. I figured that compressor would do me better in the garage than the Ridgid anyway.

                    Guy named Don showed up, mostly wanted the tanks, so the compressor issues were a side issue. I explained to him what the issues were, what I tried, etc. He told me that if he figured it out, he'd give me a call back.

                    Well, two hours later, he called back. Apparently, the air filter has some kind of sprung valve in it, which was stuck closed. It wasn't allowing any air into the cylinder head to be compressed. I kinda felt like a moron, but was glad I hadn't thrown more cash at it, because that wouldn't have done anything. I figured in the grand scheme of things, a $25 lesson and a few hours of wasted time is a small loss. But, it was odd enough that I figured I ought to update this for future readers- check the air filter system!