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Tired old Emglo compressor repair?

| Posted in Tools for Home Building on January 23, 2004 03:39am

I’ve got a old Emglo compressor that has trouble getting going in the morning 😉  It’s a 1.5 HP, 14Aamp Model M79.  Twin tank portable (hand carry) electric.  So when I first turn it on, instead of quickly accelerating to speed and building up pressure, it starts very slowly, and then after a few seconds blows the breaker for whatever circuit it’s plugged into.  If I take it in the house overnight to keep it warm, or warm it by a job-site heater it works OK.  So, is this the symptom that the motor brushes need to be replaced?  The parts breakdown doesn’t show any brushes.  It does show a large capacitor (start capacitor?). – those don’t wear out – do they?  The oil is full to the line on the dipstick and was changed about 300 hrs ago…  The directions say 30w non-detergent; should I try some thinner oil?  This all started this summer when I went to use it one day, got the same symptom (it was hot that day) and I changed to another outlet and it worked OK – assumed it was low voltage at that particular outlet.  I started to try to take the plastic motor shroud off to have a look but it was a PITA, and I needed a 9/32 (I think) wrench, which I did not have.

Your thoughts are appreciated,

Matt
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Replies

  1. UncleDunc | Jan 23, 2004 04:11pm | #1

    The start circuit in your motor is hosed. It might be the capacitor. I think it's more likely to be the switch that switches the capacitor into the circuit when the motor turns on and switches it out of the circuit when it's up to speed.

    Motors draw a lot of current when they're starting up. Circuit breakers are designed to tolerate some overcurrent for a short time, but your motor is drawing startup current so long that the breaker finally trips.

    Motors like that don't have brushes.

    Lower viscosity oil won't help.

    9/32" is just .010" more than 7mm.

  2. User avater
    IMERC | Jan 23, 2004 05:51pm | #2

    Start caps do fail wear / out and are cheap. 300 hours... an oil chage may help.

     

    Who ever invented work didn't know how to fish....

    1. User avater
      Sphere | Jan 23, 2004 09:20pm | #6

      I like the pull rope on mine, wrap it around the fan shaft. Plug it in and when it hums, pull the rope. Works every time...jus wrap the rope the right way, other wise it makes it a vacuum pump.

  3. User avater
    jagwah | Jan 23, 2004 06:38pm | #3

    Hey don't give up yet this might be simpler then you think. I have the same compressor and I've got well over 300 hours on that puppy. It does the same thing you describe and while everyone might be right about yours their not about mine.

    What I've discovered a while back that if I plug it in a circuit that the voltage is low or otherwise weak, it does the same as you say. When I go over to a circuit that I know is open, not under a load from lights ets, it fires up fast and fine.

    The switch maybe weakening and therefore needing a little hotter circuit. I find on cold mornings, especially when I'm stuck with a weak circuit, it helps to set the compressor by the heater for a moment before I fire it up.

    I'm not electric motor smart but this is what works for me.



    Edited 1/23/2004 10:44:59 AM ET by JAGWAH

    1. RustyNail | Jan 23, 2004 08:01pm | #4

      Diddo Jagwah's statement... My father was complaining about his little Emglo, echoing similar statements made above.  One jobsite was particularly a problem... I suggested the same as Jagwah, and after he switched the compressor to a different circuit, it ran fine. 

      1. rasconc | Jan 23, 2004 09:01pm | #5

        I was on jobsite and my Hitachi twinstack was not wanting to spool up.  Put the meter on recpt. and was getting below 90v if the a/c was on.  It was a poor ckt with more than a few backstab connections.  Moved to one that was new and it was not a whole bunch better.  Checked it at panel and somewhat better.  Power co came out and repaired several connections in the drop.  Later upgraded whole drop. 

  4. Brewster201 | Jan 24, 2004 12:20am | #7

    Hi there, I had a similar problem untill I adjusted  the spring loader/vent by increasing the tension. This device adjusts the air loader tension/bleedoff . It allows the compressor motor to come up speed  before entering the air reservoir . I have a picture If someone can explain how insert.

                                                                                    Thanks

                                                                                    Bruce

                                                                                       

    1. dIrishInMe | Jan 24, 2004 04:26pm | #9

      All:

      Thanks for the replies.  Now, I at least have a few things to try. 

      Bruce:

      I was wondering if my compressor may have some kind of a compression release that helps the motor get started like you describe.   I'm gonna see about taking a look "under the hood" this weekend.

      To post a picture, start a reply window, and then go about 1/2 way down with the scroll bar and you will see an "Attach Files" button. Click that.  A new window is started, and then use the "browse" function to look on your hard drive for the picture.  Once you have found the picture, click "upload" and wait a minute for it to upload - you will get some kind of confirmation, and then click "done".  The picture should be in a popular format that most people's computer can read such as .jpg or .gif.  File sizes of around 100 kb are ideal, however you can probably post one up to about 800kb, but the larger files will be slow to download for people with dial-up connections. 

      Thanks,Matt

      1. Brewster201 | Jan 24, 2004 06:59pm | #10

        Here is an attachment with the loader/vent valve. This is a spring loaded valve to the right of the air gauge and before the air check at the air receiver .

        Hope this helps

                                                                     Bruce

      2. m2akita | Jan 25, 2004 01:42am | #11

        Matt,

        If you could, let us know what you find, if anything.  Ive got the same emglo as you, and will experience the same problem.  On some of the houses Ive worked on, I wasnt able to get the compressor to work if the outlet was at the end of a long circuit.  Seems that my compressor is getting more sensitive.

        One thing I have done if it is cold out, is to start it up with no pressure in the tanks ( valves wide open).

        M2akita

        1. reinvent | Jan 25, 2004 02:55am | #12

          Starting a compressor in extream cold with no load(valves open) is recomended by most manufacturers. If you have a heater on site put it in front of the compressor for a few minutes before you fire it up.

        2. dIrishInMe | Jan 25, 2004 06:17pm | #13

          That's a great idea about  running it initially with no pressure, and I thought for sure that would it work.   I tried it this morning though, and it didn't work, however it was very cold ~20 degrees, and the "attempted startup speed" was worse than ever...

          Bruce - RE the pressure unloader - looking at my unit and the illustrated parts breakdown, I don't think I have one of those.  Are you saying that air comes out of it during the time when the motor is getting up to speed?  I do have a pressure regulator, right in between the 2 gauges (one is tank pressure and 1 is regulated pressure).   Thanks for posting the the pic - it helped the understanding.

          I'm thinking at this point I may just take it to get it fixed.  I've gotten probably 5 or 6 years of service out of it so it's not like I'm POed about it - was just trying to avoid the inevitable 1 or 2 week downtime.

          I'll let you all know what the outcome is. Matt

          1. Brewster201 | Jan 25, 2004 06:21pm | #14

            Hi Matt, could you post the illustrated parts breakdown of your a/c ?

                                                   Thanks

                                                  Bruce

          2. dIrishInMe | Jan 25, 2004 06:42pm | #16

            No I can't post the IPB.  I have no scanner, and tried to look it up online, but I guess Dewalt owns Emglo and they got it all messed up...

            Mike - I have my garage wired with 20a outlets, and also have a compressor under my bench - which is even older and more tired.... I could retire the Emglo to the garage, and yardsale the really old one, but was hoping to not have to drop the $300 on a new one yet - as I need one that I can use at job sites and it has to be one-man portable.  When I do, get a new one, I was thinking I might get a Rol-Air.   Thomas looks nice too, but get a little pricey...  Matt

          3. xMikeSmith | Jan 25, 2004 06:51pm | #17

            matt... for some reason our compressors don't die.. my twintank wheelie is from around '80-..

             our Taylor pancake has a new tank... that's from about '84  new tank about 3 years ago.... low draw.. so it gets used on the jobs with weak circuits..

             our work horse is a PC twintank... it'll trip any weak circuit.... have to go hunting for 20 amp clean ones...we got it about 2 years ago... boy is it noisy... and it always turns on just when you need to talk to someone..... arrrghhhhhMike Smith   Rhode Island : Design / Build / Repair / Restore

          4. Brewster201 | Jan 25, 2004 08:40pm | #18

            Check out http://www.emglocompressors.com , Click on emglo parts, Air mate repair parts and then to the picture of a brass valve. On this page it indicates a replacement cold start valve for your compressor

            "Has 1/8" male threads to fit our CV4X4TR2 check valve. Allows your pump to warm up before making pressure." $7.95

            Edited 1/25/2004 2:27:50 PM ET by Brewster1

            Edited 1/25/2004 2:30:05 PM ET by Brewster1

            Edited 1/25/2004 2:30:56 PM ET by Brewster1

          5. dIrishInMe | Jan 25, 2004 11:59pm | #19

            OK. I had a closer look at the IPB and the compressor does, in fact have a "Check Valve M79 includes cold start valve".  I'm gonna go ahead and order it.  I guess I missed it the first time because it's not on the pump/motor assembly or on the "control panel" assembly.  For that price it's worth a try, and it's right on the side of the lower tank behind the "control panel", so I can see it will be easy to change out.  Still though, this morning, the thing would barely "turn over" even with the drain plug removed from the bottom of of the lower tank, so I doubt that it is gonna fix it.  I just tried it again, (drain plug is still out) and it seemed to want to start a little more, but it's pretty cold out there in the garage, and the compressor just couldn't get going before it tripped the 20a built in circuit breaker.  The IPB doesn't list a separate start winding, but it does have a large capacitor - which I'm guessing must be a start capacitor, so, I guess I'll order one of those too. Matt

          6. Brewster201 | Jan 26, 2004 02:05am | #20

            Matt, I use 5-40 synthetic crankcase oil.  Anyway goodluck.

                                                          Bruce

          7. Lateapex911 | Jan 31, 2004 08:22am | #26

            Well, I'm in the same boat. My Emglo, (Dewalt) has gotten worse and worse, starting slowly, then dying!  It's intermittant, but it isn't on an extention cord, it  is inside, seventy degrees, and the filters are clean, the oil at the right level and the the tank empty or nearly empty.

            The unit is about 15 months old, and has seen moderate use.

            I am not happy.

            I guess it's off to service on Monday.Jake Gulick

            Lateapex911@optonline.net

            CarriageHouse Design

            Black Rock, CT

          8. rasconc | Jan 26, 2004 07:29pm | #23

            Did you notice the note on that website that said DeWalt closed the Emglo plant?

            Edited 1/26/2004 2:33:22 PM ET by RASCONC

          9. m2akita | Jan 27, 2004 06:44pm | #24

            Nooooooooo!!  Does this mean the old emglo standby is going away???  I love my old emglo.  Does just about all I ask of it.  I especially like it after having carried one of our other compressors.  Company has both a Thomas and the newer single tank Dewalt.  Both good compressors, but definately heavier (maybe Im just getting weaker and not smarter as I get older).

            m2akita

          10. rasconc | Jan 27, 2004 07:58pm | #25

            I don't know.  I just went to the emglo site mentioned in one of the other posts and saw this note:

            "Brand new KU pump from the factory. Ready to go. Just add oil, bolt on and go! $29 freight anywhere in the continental US! This pump will not be available after Dec. 2003 due to DeWalt closing down the Emglo factory. Better stock up now!"

            Checked DeWalt press releases and Emglo main site and found nothing.  Good luck.  It probably just means that they consolidated something, probably overseas.  I thought DeWalt bought Emglo to get into the comp. business, probably pulled a Ridgid and farmed it out.

            Bob

             

      3. xMikeSmith | Jan 25, 2004 06:29pm | #15

        matt... i retired my twin-tank emglo to a permanent spot in the garage under my workbench... it was experiencing the same symptoms as you...

        i replaced the outlet which had worn out from arcing as i plugged and unplugged the unit... while i was at it i changed the outlet to a 20 amp ( the wires were rated for 20.. the device wasn't )... and i replaced the plug on the compressor to a 20 amp plug...

        it works great now....

        another trick... you can open the drain valve for start up and then close it after the engine warms up...

        edit:  ok... so a bunch of you already got to the open valves trick.... i missed those posts

        Mike Smith   Rhode Island : Design / Build / Repair / Restore

        Edited 1/25/2004 10:31:14 AM ET by Mike Smith

        1. Mooney | Jan 26, 2004 04:54pm | #22

          I also have retired an emglo 1 1/2 hp twin tank compressor that had the same problem. I wired a household switch to the motor that I can replace cheaply. Redid all with 20 amp stuff . Works great under my table. Im fixing to order a new Dewalt for the job duties . I hope they are the same compressors. Its been a dandy .

          Tim Mooney

  5. oldsub86 | Jan 24, 2004 07:03am | #8

    You might want to pull the motor apart and clean it up good. You can get cans of electric motor cleaner spray that works real nice - a lot like brake cleaner in that it dries and doesn't leave a film. Not sure it would be safe to use brake cleaner on wiring etc. I have several times found that motors just get plugged up with dust and oil etc and fail to run well or start well. Clean them up and they are fine. Sometimes even just using an air hose and blowing them out without taking them apart does wonders. For example we have an older DeWalt radial arm saw that gets hard to start. Blow it out with air and it is fine for another 6 months or so.

    Randy 

  6. Lateapex911 | Jan 26, 2004 10:00am | #21

    I have the same issues. But my Elmglo is new...labeled Dewalt. So at the builders show, I asked Dewalt. They allowed as how it is an issue, and the only relevent idea seemed their approval of low weight synthetic Mobil 1. (Great stuff, BTW, I use it in my racecar.)

    The cold start valve idea sounds like a winner too, but it does strike me that it will solve the symptom, but not really the problem. still, it's #2 on my list!

    Jake Gulick

    Lateapex911@optonline.net

    CarriageHouse Design

    Black Rock, CT

  7. rwj47 | Jan 31, 2004 08:55am | #27

    I had a simmilar problem with my compressor,  in the winter it would  turn over a few times and then just humm until the intermal breaker on the motor would shut it down.  I got some winter weight compressor oil at the lumber yard, installed it and now it starts and runs great!  The brand was "interstate" and came in a pint bottle.  You might give it a try.

  8. Lateapex911 | Jan 31, 2004 06:33pm | #28

    In my search, I think I found that Sencos have a "cold start valve". Not sure if that's automatic, or if it's manual.

    Doubt that it's automatic, but maybe it's a manuual setting that allows the tip in to occur at lower tank pressures.

    Jake Gulick

    Lateapex911@optonline.net

    CarriageHouse Design

    Black Rock, CT

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