I've got one of those 12V tyre compressors which has become next to
useless over the last couple of times of using it. The electronics
still works, (you can set the required pressure, and it reports the
current tyre pressure), and when you turn it on it makes its customery
racket, but the tyre pressure doesn't get any higher however long you
leave it.
Opening it up reveals not much more than a smallish electric motor
connected to a piston in a small cylinder about 1cm diameter by 2cm
long. There's no obvious splits or leaks in the hose or anything, so
I'm assuming that the piston is just not as good a fit into the
cylinder as it was when new. Is there anything that can be easily
done to give this a few more months life? Will a couple of drops of
oil help to form a seal between the edge of the piston and the
cylinder?
NB.
Cylinder is metal, piston appears to be nylon, crank shaft and drive
to motor metal.

Any ideas?

pepper gurgled happily, sounding much like
they were saying:

Any ideas?

Bin it and buy a new one. They're only a few quid. Don't bother with one
with the pressure-monitoring electronic guff, especially since they're
about as accurate as the weather forecast.

On Apr 9, 10:00*pm, pepper wrote:
I've got one of those 12V tyre compressors which has become next to
useless over the last couple of times of using it. *The electronics
still works, (you can set the required pressure, and it reports the
current tyre pressure), and when you turn it on it makes its customery
racket, but the tyre pressure doesn't get any higher however long you
leave it.
Opening it up reveals not much more than a smallish electric motor
connected to a piston in a small cylinder about 1cm diameter by 2cm
long. *There's no obvious splits or leaks in the hose or anything, so
I'm assuming that the piston is just not as good a fit into the
cylinder as it was when new. *Is there anything that can be easily
done to give this a few more months life? *Will a couple of drops of
oil help to form a seal between the edge of the piston and the
cylinder?
NB.
Cylinder is metal, piston appears to be nylon, crank shaft and drive
to motor metal.

Any ideas?

Oil should really help if that's where the problem is. It could just
as easily be the valves. You could oil those too, though how long
that'd last I don't know. I'm just wondering what oil thickness to
use.


NT

On Sat, 9 Apr 2011 16:51:36 -0700 (PDT), Tabby wrote:

On Apr 9, 10:00*pm, pepper wrote:
I've got one of those 12V tyre compressors which has become next to
useless over the last couple of times of using it. *The electronics
still works, (you can set the required pressure, and it reports the
current tyre pressure), and when you turn it on it makes its customery
racket, but the tyre pressure doesn't get any higher however long you
leave it.
Opening it up reveals not much more than a smallish electric motor
connected to a piston in a small cylinder about 1cm diameter by 2cm
long. *There's no obvious splits or leaks in the hose or anything, so
I'm assuming that the piston is just not as good a fit into the
cylinder as it was when new. *Is there anything that can be easily
done to give this a few more months life? *Will a couple of drops of
oil help to form a seal between the edge of the piston and the
cylinder?
NB.
Cylinder is metal, piston appears to be nylon, crank shaft and drive
to motor metal.

Any ideas?

Oil should really help if that's where the problem is. It could just
as easily be the valves. You could oil those too, though how long
that'd last I don't know. I'm just wondering what oil thickness to
use.

NT

Grease is better than oil, at least where the air flows, as oil can be
carried in and degrade the rubber. This is more of a problem with bike pumps
as they get very hot in warm weather (too hot to hold sometimes) and there's
only a thin tube.
--
Peter.
The gods will stay away
whilst religions hold sway

PeterC wrote:
On Sat, 9 Apr 2011 16:51:36 -0700 (PDT), Tabby wrote:

On Apr 9, 10:00 pm, pepper wrote:
I've got one of those 12V tyre compressors which has become next to
useless over the last couple of times of using it. The electronics
still works, (you can set the required pressure, and it reports the
current tyre pressure), and when you turn it on it makes its customery
racket, but the tyre pressure doesn't get any higher however long you
leave it.
Opening it up reveals not much more than a smallish electric motor
connected to a piston in a small cylinder about 1cm diameter by 2cm
long. There's no obvious splits or leaks in the hose or anything, so
I'm assuming that the piston is just not as good a fit into the
cylinder as it was when new. Is there anything that can be easily
done to give this a few more months life? Will a couple of drops of
oil help to form a seal between the edge of the piston and the
cylinder?
NB.
Cylinder is metal, piston appears to be nylon, crank shaft and drive
to motor metal.

Any ideas?
Oil should really help if that's where the problem is. It could just
as easily be the valves. You could oil those too, though how long
that'd last I don't know. I'm just wondering what oil thickness to
use.

NT

Grease is better than oil, at least where the air flows, as oil can be
carried in and degrade the rubber. This is more of a problem with bike pumps
as they get very hot in warm weather (too hot to hold sometimes) and there's
only a thin tube.

These compressors are built to be cheap, not to be easily repaired. The
pistons and cylinders wear rapidly, and the valves are basically just
cheap non-return valves, which normally work by a soft plastic bit
sealing onto a hard plastic bit, held in position by a weak spring. The
springs could be broken, or the seal could have failed.

If you get more than a couple of hundred tyre inflations out of them,
you're doing well.

--
Tciao for Now!

John.

On Sat, 9 Apr 2011 14:00:45 -0700 (PDT), pepper wrote:

Opening it up reveals not much more than a smallish electric motor
connected to a piston in a small cylinder about 1cm diameter by 2cm
long. There's no obvious splits or leaks in the hose or anything, so
I'm assuming that the piston is just not as good a fit into the
cylinder as it was when new.

When my "tyreman" failed it was one of the one way valves that had
failed. This was simply a flap of thing springy metal that sat across
the inlet hole to the cylinder. It was bent so didn't seal. I can
only assume that it didn't spring shut quick enough and got whapped
by the piston.

Dismantle the compressor a bit more and see what the valves are like.

I'd not use oil, the compressor will get very hot and oil vaporise
and or become very thin and be carried into the tyre. Wether that is
a problem I wouldn't like to say, urban legends about oil degrading
rubber etc. Any lube would best be done with the merest smear of a
high melting point grease.

--
Cheers
Dave.