Coltri - mch6 - to unseize?

[CraigAClark]

Make sure you note how the rods come off. They must go back on exactly the same way.

I use mineral spirits for degreasing. An oil lubricated compressor is not a "breathing air compressor". The air isn't breathable until it has been filtered properly.

Craig

 

[rcontrera]

Ah ... this is Curt's! Yes, we sent him a matched set 4th stage.

As far as cleaning off oil, just use a rag. But if there are grease deposits or cooked on oil, then mineral spirits will work just fine. When we do work on one of these, we change the oil after only running long enough to heat up (about an hour). That seems to do a good job of cleaning out any residual old oil in the system. We then recommend that the customer change again at 5 hours.

 

[shil]

HI all,

Reassembled the coltri, after a through cleaning with mineral spirits, some black goo was found a the bottom of the oil sump which was flushed out.
As only the 4 stage complete assembly was replaced , is a running in required. ? the rest of the parts are 'run inned ' as it is. And as the new 4 th is honed , lapped to a micrometric finish does it too require a running in in. if so for how long.?

Shil

 

[pescador775]

That is a good question. I don't know beans about Coltri but I never heard of a replacement stage on a commercial compressor for the civilian market needing run in. Spares for the surplus military Kidde compressor were run in at the factory. Run in procedures require operation at progressively higher pressures. For example, 1 hour @ 1800 psi, 1 hour @ 2500 psi and 2 hours @ 3000 psi. However, those machines were built by master craftsmen who had never hear of robotics, computers, CNC, lasers and so forth. I can check the exact schedule for Kidde if you feel it will help. The Kidde uses ringless plungers(pistons) on two stages.

 

[rcontrera]

My guys just run the machine until it gets thoroughly warmed up so that anything that is left over from the cleaning gets flushed into the sump. Usually running up to pressure and doing the leak checks well will get us up to temp and give us a little run time (about an hour). Then we do another oil change and it is good to go!

Hasn't failed us yet!

 

[shil]

Well, we ran the unit for 10 minutes at idle. then cool off followed by a run of 30 minutes, at 100 bars. cool off.
We will do the final 30 mins at 200. Then an oil change as recommended by rcontrera.
By the way I was impressed by the simplicity of the design of this unit.

Shil

 

[shil]

Done. Did 30 mins at 100 bars. then another 30mns at 200. filled one tank after that. passed leak testing. Finished off by changing the oil.

Thanks to all for their helpful insights and advice.

Shil

 

[Dozdounuts]

Hey Guys I have some similarly questions about my mch6. It is an older unit but in great shape. The 4th stage has some oil dripping off of it so I am assuming that it is going and needs a new piston.
What did that cost?
I look in the old manual and it mentions SEA 30 recommended oil. I would like to get all the old oil out as I think this unit has not run in years and would rather replace it with a modern breathing air compressor oil. Should mineral spirits work for that?
The filter towers have some gunk in them so I am going to use simple green for that.
Any other suggestions to getting this unit cleaned up and running again would be great. Thanks

 

[rcontrera]

Oil dripping from the 4th stage will most likely be coming from the cylinder gasket (76) which is an o-ring. I put a picture of the 4th stage below. If you look at the gasket for the first stage (24) you can see that any seepage can leak down and eventually drip off the 4th stage as well. So your leak could be coming from any of the cylinders or the sump covers and eventually showing itself by dripping off the lowest part.

If you are planning on doing a full cleanup, I suggest replacing all the o-rings at least.

As far as cleaning out the filter towers, simple green should work great. Just make sure that you rinse it out real well so that you don't leave a "pleasant odor" behind in the breathing air.:shocked2: Make sure you remove the bottom plate on the moisture separator and clean out the spray plug. That is where the heaviest collection of gunk will be. The upper and lower o-rings on both towers are the same size. You can get away with soft o-rings if you watch the filter cap every time you change the filter, but 90 is recommended.

The best part of the old manual is the parts breakdown. The rest is mostly cautions and a little operation. There was a misprint in it that condemned these little guys to one of the least favorite for quite a while. They printed 250 hour oil change when what they really wanted was 25 hours. BIG difference!!

When you are changing over to the synthetic oil, the cleaner you can get your internals before assembly the better. The new oil will kind of dissolve or break loose baked on junk from the old oil and that gunk can gum up your valves. My guys just run for long enough to heat up the oil and then do the first change. Then we recommend that the owners change after five hours. Depending on how clean you get the system to start with, you may have to change every hour for a while until it flushes out the old gunk. Even though it only takes 1/2 liter for an oil change, go ahead and invest in a gallon of 751. It will save you in the long run and you will eventually use it all if you are doing regular changes.

 

[gav6280]

rcontrera - Which of the coltri compressors is the most affordable for private home use?

And what else is going to be needed to bring the air quality upto to a level where i can partial pressure blend rich nitrox mixes at home by decanting from my J size oxyen tanks and then topping off with the compressor?