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Bill-TGH

Medici compressor help

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$_35.JPG

I've been asked to bring an old Medici silent compressor back to life, I've managed to un-seize

and fix some wiring issues, but would really like to see a manual or schematic to confirm my guesses.

One continuing issue is a wee bit of oil spitting from the bleed regulator at the bottom of the unit. Any hints or advice on if this is normal for old units or if I've missed a step in reassembly....

much appreciated

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Well I'll be darned ... that's the type of compressor I use too and finding Instructions and schematics was unsuccessful.

Mine is about 25 years old and spits out of the "bleed regulator" or check valve too. The only solution I found was to remove the plug on the end, tip the compressor down and drain the oil from the tubular reservoir. I don't drain it often, may be once or twice a year. It'll be a combination of water and oil.

This is a terrific compressor and I'm glad to hear you got her working again.

If you ever do find a manual online, post it here, I'd love to get my hands on one too. :thumbsup:

Pete

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99.9% certain that its a rebranded Sil-Air compressor, its an older model but is very similar to the current Sil-Air 15 Export. Any manual for the Sil-Air 15 Export from that era (20 years ago plus), or any of the similar rebranded units like Aztek, Rotring or Revell should be fine.

Regards oil in the output, if the unit has recently been serviced / refilled, it's common for oil to be pumped through the compressor until the oil reaches the idea level in the motor housing, after which the problem should become minimal / non existent. Unfortunately if the head has become worn or the bore scored leakage / bypass may persist...

I only have a manual for the later automatic models, but with the exception of the pressure control unit, the auto / manual models are largely similar. There is little information on the motor itself in the manual, only replaceable external parts being detailed (Chassis P24, Motor P43);

Sil-Air Manual

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I recently found that you should bleed the air tank at least once a week via the bottom valve. My old, third-hand Sil-Air was making a high-pitched whistling noise. I took it in to Coast Airbrush for a refurb and drain before our big move, only to find that the air tank had rusted out. I hadn't even known about the bottom valve and over the years the water had taken it's toll. I ended up buying a "new" compressor that was one of several custom made for a TV make-up challenge/competition/reality show. You can bet I'm taking better care of it!

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I recently found that you should bleed the air tank at least once a week via the bottom valve.

That depends somewhat on your location, and the ambient humidity. If you're in Florida, yes, you're going to have to drain it frequently (maybe even more than once a week); if you're in Arizona, not so much.

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15_export_big.jpg

Sil-Air 15 Export (basic) is exactly it save for the grey paint job (vs Italian Red)

The manual has a warning about 15 minutes on 15 minutes off to prevent wear on the motor. As far as I can tell, the basic unit I have runs continuously with a mechanical bleed pressure relief & only a thermal shut off when hot (hasn't happened yet).

Possible problem with sensor ?

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The thermal protection switch doesn't adhere to the duty cycle & is there to prevent motor from cooking rather than being a normal part of the compressors operation & I imagine that the compressor would easily pass the duty cycle before the thermal protection switch would cut the motor out. I've never seen the manual for the non-auto models, but imagine that it may have more clearly stated instructions regards 15on/15off.

If you still have doubts on the thermal protection switch, its located inside the connector box at the rear of the motor casing / sump. I think models of this vintage rely on the plastic connector box cover to hold the switch against the motor casing & that a damaged (they can become brittle) plastic cover can prevent the switch from being held against the case, which in turn can prevent the switch from reacting at the correct temperature.

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Air-craft, at the bottom of the unit there are two valves, a safety release with the large pull ring - used to relieve pressure before turning on compressor (at least this one hates a high pressure start !)

the other valve is also a pressure relief, keeps the max psi in the tank at approx 79 lbs, quiet below that, gentle hiss when above. Its also the point where I sense a bit of oil (everything has improved with a trap at the regulator, nothing noticeable collected yet, but the smell is much improved)

In your experience is a hint of oil from this port a serious concern ?

The temp sensor sits in a metal clip attached directly to the motor housing, it seems to have a set space between the main surface & the sensor, but it may have been distorted and the distance is now too big... any thoughts on how close it should be for accurate readings ?

and on a different note, I have a second small compressor with a similar relief valve at the bottom of a moisture trap/pressure gauge combo that is ment to operate at 50-55 psi... it opens at 22... adjsting spring height & tension has no effect & I'm sure I'm using the wrong terms because I cannot find anothert example as a seperate unit. This is the unit on the compressor now... the valve at the bottom in this pic

$_3.JPG?set_id=2

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Go CO2! You'll wonder why you ever bothered with a compressor.

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its great advice and almost certainly where I'm headed personally....

but I've been asked to repair a few things for friends & fellow club members here in freddy beach.. so here we are.

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Bill,

It's pretty hard to say if the leakage is of any real concern - as said it's common for freshly filled units to expel some oil until the optimum level is found, after which is should become negligible / non existent, if cylinder wear / scoring are the cause however, the leakage will continue.... Generally speaking oil level at just below the centre of the sight bubble is ideal.

The thermal switch should be sitting against the motor casing without an air gap.

The regulator in the image looks like a standard bleed regulator & turning the knob should only open / close the bleed port to allow X to the outlet port & Y to be vented, although it may also have some form of overpressure protection - I would strip it, clean & lightly lubricate it (white grease or similar) & see how you get on.

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Bill, I'm having the same issue with a friend's medici compressor. Basically its running up to pressure, until the blow off valve opens slightly, thus creating a situation where the motor runs continuously.

 

I was thinking it might be a blow off valve that releases too early, and was going to fit a 135 PSI valve on (easy and cheap fix first). But after seeing you have the same issue, I'm wondering if it can be repaired, or if I can install a new Pressure Shut Off switch, or, repair the existing switch (assuming it has one). 

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Well crap. 

 

The blow off valve was cracked and sheared off. Bolt extractor managed to get the threaded portion out, but it appears to be a fine metric thread, nothing in my stash of compressor parts matches. 

 

I did wire in a Condor MD11 Auto/Off switch, and the unit was building pressure to the cut off, but would not start up again at the low pressure cut in point. I suspect this is due to not plumbing the unloader valve somewhere back into the compressor. 

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