MaxAir 35 (Coltri MCH-6) - Rebuilt

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UaVaj

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Location
SouthEast Florida
# of dives
I just don't log dives
so far i manage clock 60+ hours on my MaxAir 35 (Coltri MCH-6). oil change at 10 hr and every 25 hr after.

i am sure it still a long way until rebuilt, however i want to be prepared so planning ahead. as expensive as this piece of equipment is. i much rather rebuilt it early (prevent any complication) then wait for it to grenade then rebuilt. IMHO - once it grenade - the rebuilt will never be the same - so pretty much trash.



(1) at how many hours should i consider a rebuild?
(2) also what are some possible signs to look for when indicating a rebuilt soon?
(3) how much are DIY rebuild kit? what does the kit include? how much is a professional shop rebuilt?
 
Rebuild timing really depends on how you treat your system. If you change your oil religiously and run it every week, then the compressor will last you a LOT longer than if you skip a few oil changes or don't run it regularly. One of the big enemies is moisture. Any water that may gather in the oil will settle directly on the forth stage valve and piston. This will cause it to rust which in turn causes leakage. However, if the compressor is run regularly, the heat will chase a bunch of the water. Plus, there really isn't any time for the oil to drain away and leave the water behind.

There is a 100 hour service kit as well as a 500 hour kit and they include 2nd, 3rd and 4th stage valves, springs and gaskets as well as seats for the drain valves and the relief valve plus an inlet filter. The 500 hr kit also includes the 1st stage valve plate and gaskets. So, just to clarify for those that are asking themselves "why so long between valve change out?" You will use the 100 hr kit at 100, 200 300,400 hrs and then the 500 kit.

If you plan on letting it sit for a month or longer, run it to get the oil heated up and do an oil change. Then, pull the inlet filter cartridge and pour a couple of tablespoons of fresh compressor oil into the inlet and run the compressor for about ten seconds. That will put a layer of oil on the top end. Then, before starting it again, turn it over manually to free the rings ... just in case the oil has drained away and the rings are "grabbing" onto the bare walls of the cylinders.

People that take care of them, absolutely love the MCH6. Those that abuse their compressors absolutely hate them.

Hope that helps.
 
Hi Been reading the above thread and Ive rebuilt my MCH6 and could do with some advice on the little weight on the fan, Is there a special position it should be placed ?? Im asumeing it balances the crank, am I right in saying this.
Any information would be much appreciated.
Regards
Ricky
 
Guess I need to read this stuff more often! Here you go. Sorry for taking so long.
 

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Yes ... the counterweight is centered on the key.
 
Thanks for that, I can get that from the illustration, if the weight is at the top centred, the wudruff could be at 5 different positions, if I knew the exact position of wudrfuff key when weight is at top centre job would be sorted.
If this weight balances the crank I would of thought it should be in right position like a timing mark.
Being this is the only compressor Ive touched so your knowledge is how I will position it, Im used to combustion engines with compression and timing so crank weights have to be put in exact position in relation to top dead centre of compression stroke on cylinder 1.

When I turn by hand the compressor 1 full cycle there is a higher compression at the point where wudruff key is facing down to the 4th stage cylinder.
Again I may be wrong please could you advise me on my findings.
Thanks
Ricky
 
The counterweight is centered on the key.

Simple as that!!
 
Right so wudruff key facing top and centre the weight on it, cant beleive so simple.
Much appreciated mate thanks so much for your massive help.
Cheers Ricky
 
a little chip in - i have customers that use the MCH 6 as their main shop compressor - they have had over 1200 hours of trouble free use - machines never been opened , they do their oil and filter changes religiously - none of the 100 hour services mentioned above
they have the after market auto drain system fitted which ensures all condensate is removed
these machines are used daily
 
https://www.shearwater.com/products/swift/

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