# What the hell is wrong with my air compressor???



## LukieB (Jan 8, 2012)

Turned on the compressor this morning, It's in the garage with a line running out to my shop. Went out to the shop for quite a while, came back and the compressor was still running. Figuring I'm a moron and didn't close the drain valve last time I drained it, I checked that, and it was closed tight.

The motor is running, it sounds fine. I took the plastic casing off, and the cylinder is pumping. I pulled the filter off the intake and it's sucking air. I pulled off the metal line going from the pump to the tank, and there is strong air pressure coming directly outta the motor. But no matter how long it runs it won't build pressure past like 15 PSI. I can't feel any leaks coming out anywhere,(and yes, I'm sure the drain valve is closed) and I am just baffled as to where the air is going…

Anybody got any ideas what might be wrong here??

The compressor is an older Craftsman probably early nineties?


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## donwilwol (May 16, 2011)

valve(s) are gone (broke). You should be able to buy a rebuild kit for it. Replace the valves and tour back in business.


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## TaybulSawz (Oct 17, 2013)

What kind is it? How big? Direct drive or Belt? Replacement Kits can be expensive sooooo… be Aware!!!


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## todd628 (Sep 4, 2013)

How does the air get from the garage to your shop??? I would suspect that their is a leak somewhere between the two.


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## LukieB (Jan 8, 2012)

Thanks Don, but what valve(s) do you speak of? The only parts that mention valve on the parts list are the pressure relief valve and the drain valve for the bottom…

Here is the compressor and parts diagram…

The problem lies in the compressor itself, not in the lines between the garage and shop. The motor is pumping and compressing air….it's just not getting to the tank on the compressor. Like I said, I pulled off the metal line that goes from the motor/pump to the tank on the compressor and there is solid pressure there. But when I hook that line directly back into the tank, I'm not getting pressure in the tank past 15 PSI


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## JesseTutt (Aug 15, 2012)

A few thoughts:

An air compressor should have a safety valve to keep the tank from exploding if too much pressure is pumped into the tank. Check that.

I assume that you don't hear any sounds of air escaping?

If you have a shut off valve between the tank and the line running to your shop shut it off and see if the problem persists.

Is there any possibility of a leak in the tank?

If it were to run till the tank got 15 psi and then cut off I would think that the pressure switch was the problem. From your description it does not sound like this is the case.


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## crank49 (Apr 7, 2010)

+1 on shutting off the line going to the shop, and any other connections that might be leading away from the tank.

On the link you provided for the parts manual, at the bottom of the page is a link titled, "How to Fix a Valve Plate" 
Do that if you are absolutely sure the air is not leaking from the shop line.


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## donwilwol (May 16, 2011)

there has to be a valve that keeps the air in the tank. In theory a compressor work like a gas motor, just in reverse. So the piston pumps air, which typically opens a valve, then when the piston stops pumping the valve closes and the cycle starts over.

Unfortunately I can't find where that valve is in the parts diagram, but if I had to guess its B-63, which is in the picture, but not in the list.

If you remove the airline from the head to the tank, and air flows, *and you can't stop it with your thumb*, (It will flow if there's no resistance) then its something else, but the problem above has been what I've seen every time.


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## donwilwol (May 16, 2011)

I didn't watch the video all the way through, but its not for that compressor. Michael is correct, but I think the part that's no longer available on tour compressor IS the valve plate. Maybe a call to sears will get you a comparable part.


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## tefinn (Sep 23, 2011)

crank49 nailed it! It's the valve plate and/or the o-ring on the piston. Do as Don W suggested and check the pressure on the head outlet. If you can stop the air with your thumb it's in the head.


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## Underdog (Oct 29, 2012)

I've replaced the seal (30A) a whole bunch of times. It kinda comes apart after a few years, and you have to periodically replace it. Otherwise it leaks like a sonofagun.

That might be it.

Because of that leak, mine blew up when I left it unattended for a week while I was on vacation. First I knew of it, I came back, plugged it in and tried to run it. Breaker was tripped. Flipped the breaker, turned it on, and what was left of the rod flopped around until I shut it off again. I wound up buying a cylinder, rod, and piston. Oh. and the seal.

But it's been running for years since that time. I keep several seals in stock….


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## LukieB (Jan 8, 2012)

Well, it was difficult but I could stop the pressure with my thumb, so I tore into it a little further. Rubber O-ring was intact but it looked like something blew up inside there, scratches and gouges and little bits of metal and even a hole right in one of these metal flaps….. Guess I found the problem.










Now I just got to figure out what the hell I'm gonna about it. Just my luck it's the one damn part ereplacementparts.com doesn't have.

Thanks for a the help guys, you guys are awesome.


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## Tedstor (Mar 12, 2011)

Maybe Underdog will hookyou up with one from his stash


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## donwilwol (May 16, 2011)

if you can find out who made that compressor you may be able to find one. That's he most likely part to go, so I can' believe they don't have it. If you can find a compressor shop they may be able to help. Maybe even Granger.


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## tefinn (Sep 23, 2011)

That compressor was made by Devilbiss for Sears. Don't know the comparable Devilbiss model though.


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## Underdog (Oct 29, 2012)

Mine was a bit dinged up after the piston and rod blew apart. But I unbolted the reeds and flattened them best I could, then put it all back together.

It's worked fine for quite some time. Now that I say that, it will be sure to puke it's cookies again.

As for the stash, unfortunately, I don't have any other parts except those seals.


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## 69BBNova (May 1, 2012)

Hi LukieB…

The pic you posted shows (from what I can tell) only the top of the valve plate…

I would like you to pull it off the cylinder block (don't really know what else to call it) so I can see the other side of it…

With what little I see it seems that you haven't taken off the valve plate because it looks like I can see a stud sticking up from the block…

It shouldn't be all that difficult to remove it and take a picture of the underside, and I'd like you to include pics of the top of the piston and the cylinder wall before you spend any money…

If it is all dinged up it was chewing on some metal and may need more parts than you realize.


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## bigblockyeti (Sep 9, 2013)

If you're going to do a rebuild, I would highly recommend getting a full kit including a new piston (which usually has the bottom bearing and seal ring included), a new cylinder, gaskets and the valve plate. Everything is designed to last about the same length of time so you are very unlikely to replace just the valve plate and have the compressor last just as long again with only that every being a problem. I ran into the same problem with a RIDGID oiless compressor I had that was made by Campbell Hausfeld and the piston seal ring failed. Everything else looked like it wasn't going to be much later if I replaced only the seal ring. The cost for the entire rebuild was more than I wanted to spend given what the compressor was going to be used for so I ended up getting a slightly larger belt drive, oil lubed compressor for a little less than twice the price of the rebuild kit for the RIDGID. More CFM and much quieter!


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## Underdog (Oct 29, 2012)

Or, you know, you could just buy a cheapie from HF to get by…


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## klassenl (Feb 13, 2011)

Or go "shopping" on garbage day. My last compressor came from the dumpster. Works 100%.


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## tuffruss (Nov 17, 2011)

Remove the line that leads from the pump to the tank then remove the check valve from the tank it,s bad it's inexpensive replace it. It will also have another line hooked to it that goes to the pressure switch. It's a common replacement part.Good luck Russ.


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## LukieB (Jan 8, 2012)

Well, after a hellish 48 hours, as of this morning my air compressor is compressing air once again.

After tearing into it further, I found the culprit was this guy










The broken off piece was pulverized and turned to shrapnel by the cylinder. Which of course, trashed both the cylinder and the cylinder sleeve



















After a fairly extensive Internet search I found that none of these parts are available from any of the big parts websites and that Devilbliss is now owned by Dewalt, and that's why the parts that I need are no longer available on any of the websites. Clicking on the "order service parts" icon on the Devilbliss website takes you to Dewalt service parts…...ughhhh

So I broke down and called a couple local service places to see if I could get somebody to work on it and find parts, or parts that would work. The fourth place that I called said that they worked on craftsman stuff and would give me a free estimate, I explained to him the parts that I needed and that they weren't available online and he said bring it in and we'll take a look. So I drove about 20 miles out to Greeley. I took it to the service bay, The guy takes a look at it writes down the serial number, and comes back and tells me that parts aren't available for that….ughhhh

I explained to him that I had already called and I demanded to speak with the guy that I'd spoke with on the phone. They fished him out of the office and he came out and actually came up with some used parts that looked damn close, which he was kind enough to give me for free. New piston, new piston sleeve, and the top of the head that was very similar, with the valve pieces that I needed being identical. The only thing that I was missing, was the gasket that goes in between the two pieces of the head. So I stopped at AutoZone on my way home and picked up a piece of gasket material. Spent like three hours cleaning up the gasket off the old one, then fabricating a new gasket. Then I had to do some grinding on the cylinder sleeve because the new one had a flange at the bottom that the old one didn't have. Got it all put back together, and it turns out the new cylinder was about a quarter inch longer than the old one and it was knocking against the top of the head when it turned over. That was at about 2 AM Friday morn…...uggggh

Laying in bed, it occurred to me that there was no reason I couldn't bump up the height of the head with a bushing in between the head and the motor mount to accommodate for the longer piston length. So first thing in the morning, I fabricated a quarter inch thick bushing out of hardwood to see if it would work. Put it all back together….And it did!!!

Right up until somewhere around 120 psi, when my homemade gasket job blew out the side of the head. Ughhh

The gasket material that I had was a little bit thinner than the old gasket, so I had doubled it up. Thinking that maybe that was the problem, I replaced it with a new single layer gasket. I cinched it down really good this time to make sure I was getting a good seal between the two parts of the head, so good, that I compressed my hardwood bushing enough that my cylinder head was hitting again. Ugghhhh

I new hardwood wasn't a good idea for a number of reasons, but I was trying to work with what I had and see if I could get it to work.

Off to the Home Depot for a sheet of aluminum, that I used to make about 10 bushings to get the thickness I needed. So after a few more hours, I had made enough bushings to get the height I needed…...










It ain't pretty, but it's working. May not last long, but all I've got into it my time, eight dollars worth of gasket material and about nine dollars worth of aluminum….. And a trip to Greeley

Thanks for all your help guys….


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## 69BBNova (May 1, 2012)

Good to hear its up and running again…


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## LukieB (Jan 8, 2012)

Thanks Bill, your instructions to disassemble the two parts of the head was indeed where the problem lied. Its what I was doing probably around the same time you were typing your posting, LOL


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## b2rtch (Jan 20, 2010)

How much money are you willing to spend to repair your compressor?
I bought a "real " ( cast iron cylinder)used compressor for $75.00 on the local classified.


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## distrbd (Sep 14, 2011)

LukieB,I admire you for your persistence and tenacity,you don't give up easily ,do you,lol.
I hope that compressor goes on living for another couple of years if not more.


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## donwilwol (May 16, 2011)

way to improvise!!!


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