No announcement yet.

Buyer Guide: Knowing what I know now, would I buy a Coltri again?

This is a sticky topic.
  • Filter
  • Time
  • Show
Clear All
new posts

  • Buyer Guide: Knowing what I know now, would I buy a Coltri again?

    The short answer? Yes.

    I've now had my Coltri MCH 5 for the better part of 3 years. I, along with a few others, were the pioneers, and to be fair we've had issues. Only with hindsight, these same issues were in my case largely self-inflicted. In the case of others, down to lack of experience. Coltri make a very decent product, In my mind at the time of writing, there is no viable long-game alternative. Fact is, any Fuelmaker would have bitten the dust long ago. Ceatainly on the hours I and others put on Coltris
    Had I foreseen the hassles of pioneering this product I might not have done it. Despite the grief and bewilderment at times, I got there in the end. Hence, I would do it again. For the rest of you, if you read the various meandering threads on the product by the 3-4 other pioneers you could be put off. You shouldn't be. If you read them thru' you'll not be making their daft mistakes anyway. A Coltri is for the buyer able to cope with small maintenance tasks, these one-up from an oil-change on his car, but you'll need to be no more capable than that. If this is you, read the threads, hence don't make the damn-fool mistakes I and others made. You'll be fine. These days Coltri provides very good videos vai Youtube for most stuff anyway.

    Not seen in the UK, I know there are weird and wonderful supply issues in the US, (some sellers are sharks by all accounts?). I'm not best qualified to help you with these, but in my mind, the things I would take with you are this:

    You will need to add extra gauges, both pressure gauges at each stage, and a flowmeter (Mine reads a Max of 30 L/min Oxygen) off the sump and one perhaps in the supply pipe. These all to keep on top of your Coltri. I wish I'd been told this at the start. Also get a spares kit of valves, rings, O rings and oil etc etc - ie a kit of parts thrown in your deal. With these nuggets, and the brains you were born with, a Coltri is a good buy. My only real regret is not buying an MCH10. Not much more money, yet so much more long-legged. Only my supply could not cope with it. If yours will...

    Now, I understand the product, I see how a Coltri is good for galactic hours of service. Something no 'kiddies-toy' joke Phil or Fuelmaker will ever do. So you grasp what the pioneers of this product have found out on your behalf, read the threads on here, then go buy that Coltri.

    Good luck.
    Last edited by BritCNGUser; 06-09-2017, 01:25 PM.

  • #2
    Thanks for the recap of your experiences. Happy that CNGchat has provided a venue for discussions on this compressor.


    • #3
      couldn't agree with you more ol post turned novel turned manifesto turned blog was posted not for my own musings but so others could learn from my experience, last I heard brian over at the little metal shop still hasn't done a rebuild and is still on his first stage reed valve hes gotta be getting close to 20,000 hours now


      • #4
        Thank you Mr Milton for providing the platform.
        Frankly without CNGChat my thoughts on CNG and a Coltri in particular would be in polar-opposite, so indeed thank you for the platform.

        Yes, your er..novel along with 2-3 other key posts, served in large part to me getting my head around this. It demonstrates the point I'm about to make all too well.

        No amount of searching for information on the black-art of three-stage compressors and fault-finding the blinkin' things is easily available. Can't say I blame them, but the head-knowledge for this stays firmly with the pros. Even the Paintball / scuba community doesn't seem to work on theirs. At least, there's no speak of it on the web. For the rest of you, trdscfjc’s threads reveal pretty much the plight of any relative amateur working on these things. More than able, I can assure you in my many chats with trdscfjc, and from his threads, he's no fool. It's more that these things, if you've not got a real understanding, and the right kit, these are pigs to fault-find. You'll start methodically going thru' to finish-up swapping this part and the other in blind hope that something will make it work. Nothing will, it'll seem to defy all logic.

        Here's the Golden Nugget you'll all need when working on a multistage compressor:
        Because each stage relies on the previous the whole lot can stack-up and leave you bewildered. It's almost impossible to isolate the issues. This, until you have clear indication of what is actually happening. The real indicator is pressure gauges on each stage, but these alone are also near useless. However, these in unison with a flowmeter off the sump, you'll start to get soemwhere. Without that flowmeter, you've no clue which stage is pulling down the others. And if it's rings or a valve. A flowmeter off the sump measures the piston-ring blow-by, and hence you'll know which stage is dragging the rest down. As your pump pressures-up, you'll see the climb in blowby corresponding to each stage. Somethign disprportionate is all you need to know. More on diagnosis in the various threads, but in short, If you've already got figures for pressures and blowby from your freshly uncrated Coltri, you'll have a datum as the thing puts on the hours. Along with a digital Thermometer, (the non-contact laser gun type) hence temps and timing as a datum, you'll never find yourself in the mess trdscfjc and I got ourselves into. Simply because, you'll have charted what your pump should be doing at each time and pressure. Hence, now you're looking at what is amiss and why it's amiss, over running around as any headless chicken, not really understanding what you've just seen. The gauges and meters are found wanting on all but commercail-grade stuff, most three-stage compressors including Coltris, don't have them. As mentioned in many threads, these are essential, and for reasons already stated, (your log) the sooner you fit these the better. Pricey, new, buy used. Used flowmeters (look for one to read a max of 25-30 L/Min) in particualr are usually had very cheaply on eBay. And they can't wear out so a used is as good as new. Obscure industrial kit sells for pennies, whereas new... And you don't need new.
        I get blowby of approximately 10 cu ft/hr (5-6 l/min) per stage for a total of 25 to 30 cu ft hr (12 - 15 l/min). Mine reads a Max of 30 L/min Oxygen, because that is what I could get. It's not critical. You don't need a pricey methane calbrated job. Buy what is cheap.

        In conclusion
        There's better out there than me, however I fail to see how even the most experienced compressor professional will get all that far without the same information. A flowmeter and/or a digital thermometer allows you to keep on top of your pump. In fact commercail-grade pumps have computer aided diagnostics that tell a tech where to look, so I'm sure I'm right on this point. Whilst I've not seen a pump at this level, I'm sure the sensors on the thigngs to feed diagnostic data amount to much the same thing. OK, you'll not have a diagnostic panel set to show alarms at preset parameters, but these days, I've got the low-tech version of this on mine. It works.
        It took me longer than I would ever admit to get there, and knowing this serves me at last. Working on a Coltri once you've grasped this basic, becomes no more complicated than working on the most basic of engines. Dare I say, far easier. For example, no gearbox, clutch, carb, electrics etc etc you'll find working on a Coltri infinitely easier than any damnfool lawnmower/ scooter/moped. Those things are relatively complicated.

        So the long answer, yes I'd buy a Coltri again, but NOT without a flow-meter off the sump, gauges at each stage, a thermometer and a well-kept log (especially when just out of the crate) of pressures, times and temperatures. Then, they're a dream to use.

        It took the rest of us forever to get this down, you've just been given this in 5 mins. You lucky boy.

        You're welcome.
        Last edited by BritCNGUser; 06-09-2017, 01:29 PM.


        • #5
          Hmmmmm. . . . . . . . . I follow CNGCHAT from/in an incognito state. This is to keep the "never gas well'ers/never self conversion" moderators off my back. My ancient MCH-5 (purchased on the black/gray market in 2008) is still running strong with over 13500 hrs on it. The biggest expense I ever made was a "Red Head" upgrade, thanks Joe (trdscfjc). I run a knock off Anderol 750 synthetic oil (changed out every 300hrs), the usual valve jobs and those cursed drive v-belts (to lazy to align the drive motor to the compressor pulley). That is pretty much it as for maintenance. I have $1400.00 worth of re-build parts on the shelve, just waiting to use them. I may get the chance soon as the old MCH-5 is using oil more and more as time goes on (1st stage rings probably need changed), however just to lazy to rip it apart. Would I but a Coltri again? Not sure, about 35 miles from me is a guy running a Bauer K15 ( I went to see Dennis and his wife Brea, they are old school and his rig rocks. His CNG Kohler engine would save me a ton on 3 phase electric. Naaaaa. . . . . I buy would buy Coltri again, as long as I did not have to deal with David McKenna of Coltri/USA. Just say'in.


          • cngtennessee
            cngtennessee commented
            Editing a comment
            The minute I see that I am going through oil or it is coming out the molecular sieve filter, I immediately change the 2nd stage rings.

        • #6
          Jeez 13500 hours. Doesn't owe you too much does it?Reckon you owe it money! Gotta say if I didn't have neighbours, using a natural gas conversion, I'd run the whole shebang off a Subaru Robin 5hp (or a Honda),
          Bauer stuff is good, but have you seen the barking-mad prices for parts?! Two-three times the price over Coltri from what I've seen. You can pretty much buy two Coltri pumps for one Bauer. If they're better, and they might be, I have to ask, are they twice or three times better? I'm sorry but I can't believe that.

          Last edited by BritCNGUser; 08-25-2017, 02:34 AM.


          • #7
            Lawrence factor makes many factory spec aftermarket parts for the bauer (and coltri), makes cost of ownership much more affordable.

            Glad to see your post Brian welcome back !