Need some help with compressor service

[pisoiu]

I recenttly purchased a Coltri compressor block, no engine or frame, just the compressor, piping and filters. The previous owner could not say anything about running hours or anything else, except that all parts are there and the shaft can be turned normally. The primary purpose is to make it running again, secondary purpose is to get me introduced in the world of compressor maintenance. I do not have practical experience with compressors but I have a fair ammount of mechanical engineering knowledge and I own a garage full with a lot of tools. I do plan to dissasemble it completely, clean it, change whaterver is deffective or worn and put it back together.
However, I need some issues to be clarified, so here comes my humble request for help from anyone who can and is willing to offer it.
The compressor is presumably MCH-6 but I could not find a plate with model or fabrication year. However, it is a bit different from other MCH-6 pictures found on the web:
-the pressure gauge is not mounted on the moisture sepparator, is mounted at the end of the filling hose
-the bleeding point for oil is not near a piston, on lateral, it is under the main pulley
-the configuration of the first stage and the intake filter is a bit different in position than current compressors
Question: can anyone speculate what model is it, what year and where can I download a schematic of the compressor if it is different that current models?

Regarding the service, the compressor is full of oil spilled everywhere, this is due to transport. I have to clean it on the outside as well as on the inside after dismantle it.
What should I use to clean it? Is 100% acetone ok? I use acetone to clean surfaces in preparation for TIG welding, so I have some stock and I could use it for cleaning.

I attached some pictures with it. Sorry for bad quality, I cannot make better ones right now, but this weekend I will get to a DSLR.

 

[frogman62]

There is a complete one for sale on government liquidation with the frame and a Honda GL160 (4.2 HP)
gas engine. Condition is un-repairable (H) -- might buy for repair parts and extras.
Jim Shelden

 

[pisoiu]

Thank you but I'm located in Romania. A bit complicated with shipment, may cost more than a new compressor

 

[ti325v]

You have amass of work ahead of you for that little compressor..if you have lots more time then money, you can easily sort it out.
First order of business, bolt it to a table and spin it with an electric motor 5 h.p. 3,600 r.p.m. should do it. this to make sure it is actually building pressure.
Figure motor pulley size to spin the compressor at 2,800 r.p.m.
If it builds pressure....you are gonna need a frame, make sure it has a p.m.v.after the final filter and a check valve before.
Change filtration often, I think 8-10 hours depending on ambient temperature.
Change the oil a lot ! 25 hours, fill tank and let it is to cool off then do another...
Parts are available and there is actually assembly videos on you tube for this little baby.
Do not work it to hard !
Without clear pix, there is not much more advice I can give you.
It is insanely easy to work on, you can strip it down and put it back together in a day at most.
There is mountains of info here on this compressor, do a search.

 

[pisoiu]

Thanks for your answer. Free time is something I usually lack, but I try to work on it when I find some...
Actually I decided to disassemble it completely before turning it on and I am glad I did it. Here's why: during transportation, it was tumbeled and rolled in all directions. There is a small hose connectig the cylinder used to put oil inside and the first stage. I do not know the purpose of this hose, but due to tumbling, the oil made its way from the inside of the compressor, through this hose, into the air filter and air intake section. This, plus some "let's see if it spin" moves of the shaft, and it passed the valve to the inside chamber. Turning it on at full power would not be such a good idea, trying to compress the oil in the first stage...
The whole compressor was quite dirty inside and I did a preliminary cleanup, meaning wiping out all the oil residues and other big dirts. Later I will do a more thorough cleanup with acetone to disolve all small dirts and oil. The segments needs to be extracted and cleaned, etc. Same with valves and there is some rust which must be cleaned here and there.
I encountered two problems and I need some advice:
-I was not able to open the valves mechanism on the first stage. How does it open? There are two caps which holds the springs and the valves. Are the caps threaded or inserted with pressure?
-the connectiopn of the first stage piston rod to the crankshaft has some bearings made with small cylindrical pieces placed on the inside of the rod hole. It looks like one or two of those small pieces are missing because there is a space between them. On the other rods, this space does not exist, all the small cylinders are there on all circumference. Is this normal or not? How bad is it?
-the pipes which connects stages can be dirty on the inside. How should I clean them?

 

[rcontrera]

You definitely have a project compressor! That compressor is at least 20 years old. In 1995 Coltri changed the first stage valve plate and replaced the screw in valves with reed style valves. In addition, in 1994 the inlet filter housing was changed to a replaceable cartridge style. You can see from this exploded view that they also have changed the first stage head.

As for cleaning, I am not a big fan of using anything that could leave a nasty residue. So, I always go with something that I can neutralize with an "opposite" like an acid and them a base. But my favorite cleaner is just plain old Simple Green since it rinses well with water.

If you don't have a manual for the MCH6, you can download from my site at CompressorStuff.com/manuals/

 

[pisoiu]

Yes, it is a bit old but as far as I can see, it is in fair shape. I purchased all the orings required to be replaced and I will go on with cleaning.
I have its schematic, from there I took the information required to replace orings.
Thanks for your help.