I attempted to post this earlier but it has not appeared. Hope it
doesn't pop up twice.
I recently bought a military surplus 2 stage Curtis-Toledo compressor
driven by about a 12HP B&S engine.
I cannot get the compressor to turn over by turning the flywheel. The
oil in the compressor and the engine is brand new. I don't know why
the military auctioned off the compressor.
I'm wondering if it got water in it or something. How can I get some
light weight oil into the cylinder? If it's toast is a rebuild a
major big $$$ undertaking?
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.
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?
into the cylinder
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.
If you don't see any other way take the piping loose that links the compressor
tank. You should be able to get some in there, perhaps not enough, but it would
I knew a young man 25 years ago who pulled the injectors for an old single
mover, poured in a bunch of MMO and went back a week or so later with a good
turned right over. Good stuff.
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
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
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.)
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
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... ;-)
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
[ ... ]
[ ... ]
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
Two different versions to choose from. There are probably others to be
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
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. :-)
[ ... ]
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.
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
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.