Frozen compressor

Separate the motor and the compressor. Find out if one or both have pistons stuck in the cylinders.
Remove spark plug(s) on the motor and the head of the compressor if they are both stuck, generously apply Kroil or similar release agent. Allow to sit, then attempt turning the flywheel again. Look into getting a long cheater pipe to use on the flywheel(s) without bending or hurting it.
Another common method of getting the rings loose is Coca-cola.

I unstuck a frozen compressor once by using a hydraulic jack to turn the flywheel. I tried to be careful and inthe end, did not damage anything.

I've known folks to swear by Marvel Mystery Oil. Just pour generously into the cylinder heads and let stand. Then use a cheater. You may wait days or weeks but it will eventually penetrate it.

Dan and everybody,
Indeed I have already separated the engine from the compressor. I removed the protective cage from the belt drive and removed the belts. Prior to doing that I thought that the Briggs & Stratton engine was icky although it did turn. After removing the two V belts it became clear to me that the motor is entirely free. The belts were simply slipping on the large compressor fly wheel.
Is there a way to get oil in there without removing the head? My problem is that I don't know anything about the innards of compressors. This appears to be a single cylinder 2 stage compressor good for 175psi at 15 cfm (if my memory serves which often doesn't).
If I get the thing to turn freely does this imply that it's "good to go"? Or is machine work called for?
Thanks!
V

into the cylinder Al,
I'm one of those who swears by MMO. I buy it by the gallon. When I buy a reciprocating engine that's been out of commission I generally dump some down the spark plug hole. However, I don't know how you reach the top of a piston in a compressor.
V

If you don't see any other way take the piping loose that links the compressor to the tank. You should be able to get some in there, perhaps not enough, but it would be a start.
I knew a young man 25 years ago who pulled the injectors for an old single barrel earth mover, poured in a bunch of MMO and went back a week or so later with a good cheater. It turned right over. Good stuff.

Dan, I imagine the active ingredient in Coca Cola is phosphoric acid? If you use Coke do you use sugar free? Seems like the 9 tsp of shooga down inside there would be kinda gooey.
V

Removing the heads should be quite straight forward. There should not be any loose parts inside, just a reed plate. Make some kind of mark so you can put it back on the same way it came off. There should be about 6 bolts holding it on, bump the head with safe hammer or wood block to pull the reed plate. Unlike internal combustion engines, there is no timing or sequence to the compressor head.
No one can tell you what is wrong with the compressor yet. Either the rings are rusted in the cylinders or the rod caps are galled to the crank. If it is light rust, you may not need to do anything else.

It did show up. I see that you're posting from googlegroups, and you should be warned that it can sometimes take several hours between posting an article there and actually having it show up there. However, the articles get to the outside world (where news servers work properly) fairly quickly.
By now, you should be able to see quite a few answers to your first try. (At least *I* saw several answers.)
Good Luck, DoN.

564 > =A0 =A0 =A0 =A0 (too) near Washington D.C. | > =A0 =A0 =A0 =A0 =A0 =A0--- Black Holes are where God is dividing by zero =

(...)
I use Mozilla but I understand there are programs out there with very sophisticated message and thread filtering.
Need a newsgroup server? It's Free!
--Winston

It can't be a single cylinder and a two stage at the same time...
Two stage normally implies a multiple of two (four, six, eight) cylinders - and the second stage will be physically smaller. Of course, they could do something really odd like having three feed two...
Depends on the condition of the other internal components - it might turn freely and be fine after freeing up a stuck ring and minor repairs like that missing air cleaner. It might have to get torn down for inspection and possible internal parts replaced. You won't know for sure until you get it spinning and see if it'll pump- they usually make strange noises as a warning if it has bad problems inside.
You have a piston going up and down in a honed smooth and round bore with piston rings to make a positive seal, just like a gasoline engine, with a crankshaft and connecting rods with babbitt or ball bearings just like an engine.
And oil seals at the ends of the crankshaft to keep the oil in, and either oil slingers on the connecting rods or a pressurized oil system for lubrication just like an engine.
The only big difference is instead of mushroom style valves and a camshaft in an engine, you have reed valves or other simple check style valves for controlling air in and air out in the heads. And no sparkplug or other 'direct access' to the cylinder.
And for gasoline engine driven compressors you have an "Unloader" system that holds the valves open to stop the pumping, and releases the throttle to allow the engine to remain running and drop to idle when the call for air stops.
(This is also useful in big shops with constant air usage but not requiring the full output, like in sandblasting or multiple machine tools. It's bad to start an electric motor more than 4 to 5 times an hour, they burn up. And you have to pay Demand Charge adders on the electric power bill from all those start surges - better to start the motor once per shift and let it run unloaded when not needed.)
Compressors with pressurized lubrication also use that oil to run the unloader valves, so the pump won't stall out the prime mover (electric or gasoline) by starting to pump until after the compressor gets up to full speed - and is not out of lube oil. (Safety system.) If you see an oil pump and small pressure gauge on the end of the crank opposite the pulley, possibly a small spin-on filter, and an ~1/8" oil line heading up to the heads, you have this.
Oh, and copper head gaskets can be annealed with a torch to dull red hot (double check that temperature before trying, it's from memory) and reused at least once in a pinch. But parts should be cheap and easy, they do not make many radical design changes - the 2008 units look a lot like the 1950 units. If it ain't broke...
That's it in a nutshell, and in English. When you're done give it back, I've got a hankerin' for walnuts... ;-)
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Bruce, that was incredibly helpful. Thanks. Since "it can't be single cylinder and two stage at the same time" then I stand corrected about it being one or the other. The data plate mentions so many cfm at 175psi. The cylinder does have a secondary "protrusion". Maybe this is the second stage piston. I was confused because it is so much smaller.
V

The second stage is smaller because the volume was reduced in the first stage.
Pete Keillor

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Shouldn't that be "Holy guano"? :-)
Well ... my news reader is slrn -- which came into life on a unix system. A quick look around Google shows that there are versions of slrn compiled for Windows system. The first one which I found was at:

Two different versions to choose from. There are probably others to be found.
But while there are problems using a web browser as a newsreader, your primary problem with things not showing up in a timly manner are attributable to the Google interface itself, not your web browser. I don't know *why* the Google interface shows articles from outside a lot more quickly than those posted from within its interface. It might be an intentional attempt to control spam posting from the Google interface -- perhaps hold onto articles long enough to see whether there is a flood in unrelated newsgroups before letting them escape -- except that people on the outside see them failry quickly.
With a good newsreader -- or even with a browser acting as a newsreader, you can connect to many commercial sites and some free ones as well. The one which I use is newsguy (check out to read about what they offer (including a Windows based newsreader free for the download -- but I can't say what it is like, because I don't use Windows for newsreading. My one token Windows box is so far behind on patches that I would never connect it to the outside net -- just to my private net behind a good firewall which keeps it from seeing the outside at all.
Newsguy's prices are reasonable -- the service which I selected started out at $9.95 per month, and then I picked up the once yearly payment of $99.50 per year (I may have the last digits wrong). Since I don't visit binary newsgroups, I never use my full bandwidth, and aside from Newguy boosting the monthly bandwidth allotment for users who have been on for a while, they also let unused bandwidth accumulate, so I now have over 1.2 Terabytes of bandwidth available -- if I wanted to go wild downloading from the binaries newsgroups. :-)
Others can point out other news servers, I only speak about what *I* know. I used to have an ISP which gave me a true news feed so I could run my own news server -- but they were bought, the new company dropped the newsfeed, and then dropped their news server as well, so I moved to another ISP with a T1 feed -- and they just dropped the monthly charge by $200.00 for my last three-year contract. It is nice to have that extra $200.00 per month for tools and other toys. :-)
Enjoy, DoN.

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Yes -- that makes it two stage. That smaller cylinder allows compressing air which has already been compressed once without having a great deal of force on that connecting rod. As it is, I suspect that the two cylinders need about the same force, so the crank is balanced.
I may be a bit late with this, because I was not able to get to the newsreader last (Monday) night before I went to bed.
Enjoy, DoN.

If you are seeing a 175 PSI output, it HAS to be two stage.
As a practical matter, 125 PSI is about all you can get in a single stage shop air compressor without building it solely for high pressure and getting very poor CFM volume output.
Really high pressures like filling scuba tanks are 4 or more stages, they keep boosting the pressure in increments till they reach the target.
That, and the two crank throws (and therefore the pistons) are usually out of phase with each other on purpose, so the first stage is on the exhaust stroke into the intercooler at the same time as the second stage is on it's intake stroke. Just enough time for the air to dump some heat on the way through.
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