Milwaukee M18 air compressor leak down fix

[phobby]

Let me start out by saying this is likely my favorite and most used tool. I have to say Milwaukee has made a few manufacturing errors bc I've had two issues by chance with it. Then again noting replaces a portable air compressor that can inflate HD truck tire and my gooseneck trailer tires so easily. 

 

1. I keep it in the back of my truck 24/7 but under a bedcover so minimal rain gets to it. Milwaukee chose to put the controller board for the compressor on the backside of the plastic where FUEL brushless is labeled. Then proceeded to add the handle to the opposite side, which I placed it since I had it against the bedside with the handle up and a bungee cord holding it there. If rain gets to the compressor ir goes down and pools on the backside of the plastic labeled Fuel brushless bathing the controller board. Mine ended up failing. 

 

2. My compressor began having a slow leak after 5-6 months or so and noticed if I left the switch on it would randomly pump back up. Which if you know this compressor it Loves a battery as the only one worth having for it is the M18 12.0. I poured soapy water over all of the connections I could find with no leak. Finally I found it and fixed the issue the pressure regulator knob. Release all air pressure first.

 a. Take off the top cover over the battery compartment- four screws in the corners under the black sticker hold it on.  Marked in the photo below. 

 b. The adjustor knob has a tiny Allen screw that has to be backed out a little it only stops the knob from twisting off. 

 c. remove the knob and a spring under it. my spring was very rusty. Below the spring is a white plastic plunger that needs to come out. its kinda tricky to get out bc of the gunk. 

 d. Lastly inside after the white plunger is a nut that has a center hole for the white plunger. back the nut out and a spring with rubber tip should come out with it, Also a small Oring is on the backside of the nut to seal it. 

 f. clean all the gunk, corrosion, build up and so out of it plus all the dirty parts. Oil everything as I used a gun oil that was handy. Assemble in reverse order. 

 Now your compressor should be back sealing and staying pressured up without randomly draining a battery. 

[wireman]

Thanks Phobby,

 

Great job, you saved me a few bucks.  I always used mine to fill tires. It did not leak when it was at max pressure.  as soon as I dialed it down it would just drain the air tank.  Mine has never been wet.  I was surprised with the amount of corrosion inside the regulator. 

 

A couple of things to add:

 

The screws under the label are torx not sure what size but an allen will work.

the nut is 15mm

I used some white grease during reassembly.