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look what I found lurking in my 3rd stage head (MCH5)

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  • Re: look what I found lurking in my 3rd stage head (MCH5)

    Brit, what was your cfm flow when venting to atmosphere?

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    • Re: look what I found lurking in my 3rd stage head (MCH5)

      ordered 1st stage rings today from Nuvair, still waiting to hear back on the new 3rd stage valve/piston kit

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      • Re: look what I found lurking in my 3rd stage head (MCH5)

        I am starting to see the currency in why only rings (or in Coltri language 'segments') are not necessarily the solution. You recall I have 3 x sets of rings reaplced but collect maybe 100ml of oil in my coelescing filter every 5-6 fills. Either the bores need honing or I need new barrels. Blow-by can be the only reason for this
        [Oil usage at thsi level is also why putting my coelescing filter in before my tower filter saves the MS and AC, that much oil would have trashed my AC.)

        Brit, what was your cfm flow when venting to atmosphere?
        Not time now, I now have a priority valve on order - I am told this will be a Coltri part as fitted stock to the larger units. Awaiting for all my input gauge parts to arrive, and the valve. I will start working on thsi for the coming week...
        Last edited by BritCNGUser; 03-21-2015, 03:02 AM.

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        • Re: look what I found lurking in my 3rd stage head (MCH5)

          brit, just reread this ...are u sure you put the oil scraper ring on the bottom (facing down) of the piston? if not this could cause the oil to infiltrate your filters

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          • Re: look what I found lurking in my 3rd stage head (MCH5)

            Yes made sure the bottom ring (the one nearest the crank) is fitted correctly. If I recall correctly the lower ring is 'L' in section on both the 1st and second stages. Thus the lower horizontal (as against the vertical of the 'L') goes towards the crank, or it sits farthest away. Frankly I can't remember how this was now. I was sure to put mine back on the way these came off.

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            • Re: look what I found lurking in my 3rd stage head (MCH5)

              Oil is actually fed into the compressor through the first stage as well as the third stage. On the first stage, there is a line that goes from the sump to the suction of the first stage. This top lubricates the rings and that lubrication carries on to the second stage. On the third stage, the pusher piston splashes oil into the third stage floating piston and excess drains back to the sump. However, there is always going to be some carryover. In an air system, there is a moisture separator that pulls off moisture and oil from the second and third stages before it hits the filter chemicals.
              Ray Contreras
              CompressorStuff.com

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              • Re: look what I found lurking in my 3rd stage head (MCH5)

                There have been multiple mch5's on here between 2and 3 thousand hrs with the same situation of low flow even after considerable parts replacement one even received a factory replacement.so do the dealers know this is the life of these machines and remaining mum, or????

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                • Re: look what I found lurking in my 3rd stage head (MCH5)

                  That is a good question. Can any with the mch5's chime in with the hours of operation on machine. If I am to get one for myself I will run the heck out of it.

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                  • Re: look what I found lurking in my 3rd stage head (MCH5)

                    Originally posted by NortherIllinoisChuck View Post
                    That is a good question. Can any with the mch5's chime in with the hours of operation on machine. If I am to get one for myself I will run the heck out of it.
                    If you buy a coltri it is a given you are going to replace oil and valves periodically, add some gauges and become somewhat of an engineer. This is the whole appeal for me. You can find manuals, parts and video tutorials a few keystrokes away on the internet. It is entirely user serviceable. If you do "run the heck out of it" you will probably replace a few bearings and get intimately familiar with the inner workings of it. If there is a need to identify the shortcomings of a coltri it would appear that the second stage bearings are overloaded and wear prematurely. Once you know this and plan on periodic replacement it doesn't seem like a dealbreaker to me. It is a very simple machine and a great introduction to basic mechanics if you are so inclined.

                    If you don't like getting your hands dirty, get a fuelmaker. My kitchen stove is more complicated to operate than a fuelmaker and you never have to do a lick of maintenance on a fuelmaker until it won't start and flashes an error code at you. I have had one for three years and it is great until it breaks and you need to pay a service tech to make a housecall or pack it up and pay $100 bucks in shipping to get it to someone who can work on it. There are a few members on this forum who have worked on their fuelmaker but they are going into uncharted territory without a guide. If the electronics stop functioning there are no circuit diagrams available and no troubleshooting guidelines. Amfuel is an exceptionally knowledgeable guy when it comes to the fuelmaker and if it stops working he can help you locate the nearest service facility.

                    If fuelmaker parts and documentation were readily availableto the diy'er I wouldn't have lost interest in mine.

                    If the coltri seems too flimsy for you, you could buy a bauer and get pressure lubrication and the finest german engineering. It will still need oil and valve changes periodically and the parts will cost more than a coltri. I also own a bauer and don't like it any better than the coltri. There is less info on the internet about DIY service but it is still pretty darn simple and parts are readily available.

                    If you are prepared to hire out your maintenance, you and flattracker are probably better suited to the fuelmaker with its thousands of hours of hands off operation.

                    Good luck with your decision.
                    Karl

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                    • Re: look what I found lurking in my 3rd stage head (MCH5)

                      As i stated earlier i think the 2nd stage wrist pin and bearing should be replaced every 2000 hours, that is by no means a deal breaker

                      my 1st stage rings will be here tomorrow, i will post my results after installation

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                      • Re: look what I found lurking in my 3rd stage head (MCH5)

                        not trying to badmouth anyones machine my point which i dont seem to be making very clearly is no one at least among those that post on this board has done a simple overhaul on one of these and got it to pump back at rated capacity. either everyone is doing something wrong or at the 3000 hr mark neighborhood these things are needing new pistons, cylinders, heads??? which puts cost out where you have to compare just replacing the bare compressor. If I got it wrong why are the dealers not piping in here and stating these are 10,000 hr machines and here is what your doing wrong?

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                        • Re: look what I found lurking in my 3rd stage head (MCH5)

                          FT, i have not changed the 1st stage rings yet, hopefully that is it.....if it is then we all know what happens when the rings go out

                          as far as it running for the long haul, i am confident it will (it is pumping as of right now, though at reduced output)

                          i dont think the pistons need to be changed, only reason why i would install a new piston is to upgrade to the new head design that is on my to-do list
                          Last edited by trdscfjc; 03-24-2015, 01:22 AM.

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                          • Re: look what I found lurking in my 3rd stage head (MCH5)

                            If you all recall I have low pressures on both 1st and 2nd stages. 35 and 350 psi respectively. Now my thinking (with prompting from others) was that I must have a 1st stage blow-by pulling the two down. To recap - I have already replaced 3rd stage rings & valves, 2nd stage valves & rings and cylinder and 1st stage rings & valves.

                            I will admit the logic is somewhat flawed but I have a new 1st stage barrel factory honed, so I stuck it on last night. Agreed this being with the new(ish) ringset (about 15-20hours) I already had on the first stage. Yes I know - flawed logic, but I had the time so I thought I will at least give it a go.

                            No difference, if anythign it is worse. 1st stage is still at 35 psi. I measure the pumps performance by my pressure-up times - how long it takes from zero pressure blow-down to the high pressure switch (set 200 Bar) tripping with the fill-hose away from my car. Before I did this barrel cahnge I had a time of 3mins 15 secs, ( extra Coltri tower filter and Parker type Coelescing filter in the pressure circuit) and after the new barreI I had 3 mins 25 secs. So worse. But after I did the ring change on the 1st stage (without the new barrel) 5-6 hours running-in improved my pressure-up times by 10-15 secs. Only now my rings are not new even if my barrel is , so perhaps I won't see thsi leap again.

                            So in truth I have proved nothing because my rings are not really new anymore and if first stage blow-by is the issue I have not shown this by my actions. It was a vain hope. It got late last night, so I stopped. I have another set of 1st stage rings on order but four weeks to delivery. I should probably have waited and done it all in one hit. To eliminate my gas inlet supply I ran the pump with the input straight to air and saw no improvement either. Today I removed the input filter, I was hoping the issue would be as simple as a blocked low-pressure filter but nope, clean as a whistle.

                            Yes, I accept the above was not logical but I'm clutching at straws here.

                            Now the prudent thing here might be to put it all back again, thus refit the old 1st stage barrel because if young Karl is right (and I think he might...) I will scrape off the nice new honing off my nice new barrel which when the nice new 1st stage rings do arrive will be circumvented yet again. Oh for cryin' out... Or should I go for broke, run it up for 4-5 hours with the new barrel and nearly new rings waiting for them to seat. Only I do recall even during run-in when this pump was new it verily flew and did not improve if at all the fill times after run in.

                            I think I should do this soon before the honing goes and get myself a flow meter a la karl's words.


                            Note: Coltri in their parts books and maintenance videos don't make this clear - The first stage rings come as four rings (2 tapered + 2 serrated oil control rings) If you are not looking you will not see the tapering... I was careful to be sure the 2 x tapered rings have the smaller diameter to the top of the piston. Thus the bright wear pattern visible on the rings is seen to the lower half of the rings (nearest the crank) when fitted.
                            Last edited by BritCNGUser; 03-24-2015, 06:22 AM.

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                            • Re: look what I found lurking in my 3rd stage head (MCH5)

                              I strongly recommend considering the amount of time and money you have thrown at these machines a piece at a time you pull the bottom end down and check or replace the mains. I know of one other of these machines, not on this board that , that had to have mains replaced at 2300 hrs due to slow pumping.

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                              • Re: look what I found lurking in my 3rd stage head (MCH5)

                                the amount of rod bearing damage you had the bottom end needs cleaned any how.

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