I got a compressor with unknown history. Startup precautions?

[USNMARS]

I just won yesterday a pallet of 3 (what appears to be MCH-6) compressors from a govt surplus auction. I am planning on verifying all of them run and then passing them on to the local Dive Recovery Unit. The dive team will do their own air testing on them but aside from oil and filter changes, are there any precautions I should take before I get them running? I do not know how long they have been sitting or their history but they do appear to be like new. Is there any rebuild or maintenance I should do before even trying to turn them on?

Thanks in advance,
Eric

 

[scubastevesa]

other than fresh oil and filters - i would check that the intake dust filter is in -
I would also look inside the 2 silver tubes 1 is the condensate tube - the other houses the main filter - sometimes these need a clean out
use a long cloth and ram rod it down there ( make sure you can hang on to a piece to pull it out) ( remove spring in filter housing first )
remember to do a oil change at first 5 hours and thereafter every 50 hours ( Coltri synthetic oil CE 750 )

 

[rcontrera]

I agree with ScubaSteveSA with one tiny exception. I am very conservative when it comes to oil and filter changes so I suggest 25 hours. Oh, and in the US, we use 800, 751 or 455 since the 750 is a European oil.

One note ... if they have been sitting for a long time, check the oil very well as you drain it to make sure there is no water in there. If there is, you may have rust on the 4th stage piston, cylinder, valve seat or valve spring.

 

[mustang_5l]

Darn! I'd be interested in one if you were selling

 

[Peter69_56]

Are you sure it has had only synthetic oil in it. If its had mineral oil in it and you change to synthetic it will gunk up the compressor and cause major problems (see Michael McFadden's web site for a great story on this).

Also are you sure its not a Chinese copy of the coultri, if it is beware. The final filter might be a tube that passes oily water and air rather than a filter. If you open it and it doesn't have a removable cartridge that can be replaced, you may have junk. The one I bought had a small refillable tube in it with a small amount of filter material but it didn't seal thus bypassing the filter material, pumping oil and water into all my tanks. My chinese copy didn't pump at the rated 100l/m either (more like 50l/m)

 

[iain/hsm]

Also are you sure its not a Chinese copy of the coultri,

They are genuine Coltri units Peter you can see from the photo
The Chinese don't fit SOGA motors

Cheeky lot if they are calling them Coultri or was that your typo?

 

[pisoiu]

After I purchased an identical model, but the compression part and filters only (no motor or chassy), the first thing was to disassemble it completely. It was a smart move, found it only after I disassembled first stage, because the compressor was tumbled and rotated in all positions with oil in it. Because of this, the oil sipped through that small flexible tube inside the first stage, it was almost full of oil. If I had turned it on without inspection and with the first stage filled with oil...well..bad idea.
After I cleaned everything and replaced some worn components, I installed it on a diy frame and an electric motor, and now I have a fully working compressor. It was an interesting project, my first serviced compressor.

 

[Peter69_56]

They are genuine Coltri units Peter you can see from the photo
The Chinese don't fit SOGA motors

Cheeky lot if they are calling them Coultri or was that your typo?

No they don't call them Coultri, but they appear a bad copy of the earlier model. For all intents and purposes, they look just like a earlier model coultri on the outside, but where it counts (inside) they are crap. They do not pump the rated amount, and the filter has a small tube inside rather than a cartridge which holds a tiny amount of material and also is so badly designed that the air bypasses the filter material contaminating the tank. They promise the earth for warranty and then give nothing when they fail. They sent the wrong filling hose (and spare) and then wanted to charge me to send 2 more, so I only got one, which also had a crap hydraulic hose instead of air hose.

Glad you got the real deal. Everyone else, beware the copy. I now have a bauer and am very very happy.

 

[CraigAClark]

Before I did anything else, I would make sure they rotate freely by hand. also be aware that the filtration may not produce grade E air.

 

[Peter69_56]

Before I did anything else, I would make sure they rotate freely by hand. also be aware that the filtration may not produce grade E air.

The filtration on mine produced A grade oil/water. Had a brand new faber 12 litre steel with rust in it and 8 contaminated tanks, on first use of the compressor. Complained and was told nothing they could do as it was "my fault"