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

    Yes, I start the machine up and find less than 30 cfh blowby and by the time it shuts down it is over 30cfh. I presume the cylinders seal less well when hot???
    Karl

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

      OK, thanks for the info, I didn't get that far. My readiings taken after 5-10 mins running. I was concerned about leaving the flowmeter hooked in because I thought it might restrict or deprive the first stage of oil vapour. I will keep digging. I have a compltely new 3rd stage Red type valve assy on order due to arrive on Sat or Mon. I will keep plugging away.
      Last edited by BritCNGUser; 04-30-2015, 04:32 PM.

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

        Upon reassembly I found that the wrist pin was rather tight in the first stage piston, only way I was able to assemble was to press the wrist pin in with my arbor press and then stick it in the block and then install the crankshaft (threading it through the big end of the already assembled connecting rod/piston assembly)

        Despite the order of assembly in the coltri videos you sometimes need to get creative.

        Just a tip if anyone runs into a similar problem

        Another thing...
        Pay close attention to the assembly of the bearing races on the big end of the connecting rods.

        They should stick out equally on each side, only way to do this is to have some sort of relief on the backside of your press, this allows the race to pop out the other side....again make sure they are equally sticking out of each side.
        Last edited by trdscfjc; 05-02-2015, 06:19 AM.

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

          i wouldnt run it that way if you had to press the wristpin in something isnt right.

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

            I had the same issue with my 2nd stage gudgeon/ wrist pin. Used a socket slightly smaller than pin diam and a long nut & bolt thru' the lot with a larger socket at the other end all acting as a puller. It is an interference fit but er... tight. First stage was the same.
            Last edited by BritCNGUser; 05-02-2015, 08:45 PM.

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

              DwyerMagnehelic02.jpgRotameter.JPG
              Last edited by BritCNGUser; 05-04-2015, 12:53 PM.

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

                Nice looking flowmeter. It appears a lot more substantial than the dwyer I am using. I have the same manometer just a different scale. It is a really nice gauge for the price.
                I have a pressure sensor installed on the inlet to my coltri so it will shut down if the inlet pressure approaches zero. Was the inlet restrictor you refer to inside the first stage head or externally installed?
                What kind of impact did removing the inlet restrictor have on the blowby?

                Sometime back in this thread (or a similar one) a forum member mentioned that pulling a vacuum on a crankcase will improve ring sealing. If it is true I would think restricting your inlet would increase suction on the crankcase breather and improve ring sealing???
                Congratulations on solving the problem!
                Karl

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

                  Originally posted by BritCNGUser View Post
                  [ATTACH=CONFIG]4969[/ATTACH][ATTACH=CONFIG]4970[/ATTACH]
                  Brit I am afraid you are going to be horribly disappointed, an inlet restriction may have caused some reduced pumping rate but it certainly didn't cause the heat damage you and others have seen. There are no design differences between a compressor and a vacuum pump only a vacuum pumps produces only a fraction of the heat a compressor does.a reduced pumping rate if it is caused by low inlet pressure doesn't make more heat it makes less.

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

                    Is the heat damage you refer to the hammered wrist pin bearing or carbon build up? I just bought an old eagle/davey compressor with a leaking third stage. When I disassembled to clean and reseal it, it also had plenty of carbon build up. It seems to come with the territory in the few compressors I have looked at. Maybe fuelmaker was onto something when they decided to go with an oil free design???

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

                      Originally posted by karl View Post
                      Is the heat damage you refer to the hammered wrist pin bearing or carbon build up? I just bought an old eagle/davey compressor with a leaking third stage. When I disassembled to clean and reseal it, it also had plenty of carbon build up. It seems to come with the territory in the few compressors I have looked at. Maybe fuelmaker was onto something when they decided to go with an oil free design???
                      His hammered wrist pin bearing , scuffed cylinder, carbon buildup, none of those were caused by low inlet pressure.Low inlet pressure can reduce your pumping rate but it certainly won't kill your compressor. I look forward to hearing exactly what the restriction was and why brit thinks it didn't impede his fill rate earlier but is now?

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

                        Karl, it is thanks to your post on flowmeters that I got to it as quickly, although far too slowly! OK, I suppose i would have found the scuba compressor forum and the thread there eventually. I have been searching interweb for this stuff, but you found it for me an d got me thinking that way. Thank you. My flowmeter is a beast of a thing. Only next door's cat knows how old the thing is, solid brass castings, and RSJ joisting for a cage. Mad it is. If you threw a modern Dwyer at me, it'd be kiss. This thing would kill.

                        Now before you all I vow, I will never ever work blind again. Especiailly when ex-industrial used process-gauges can be had so blinking cheap.

                        MobreyFlowmeter01.JPGTest one: Connected to my gas supply I was gettign crazy heat, slow PU times, my Dwyer Magnehelic on inlet would drop from a static 2.1Kpa /21Mbar (Coltri spec 17Mb) to when running 1.5Kpa / 15Mbar (less than Coltri 17Mbar spec)

                        Test Two. I ran my pump inlet open to atmosphere. my past tests with no gauges had told me nothing. Now with gauges I saw

                        A) With my hand held even slightly over the inlet to restrict sees blowby double, my second stage pressure skyrockets to 40-45 bar ( the 2nd stage gauge jumps up and down - it made the 3rd stage inlet valve let go??) and the temperatures on the 3rd & 2nd stage skyrocketed too. I now summise this caused the heat I've seen ruin my 2nd stage and 3rd stage. Certainly with the Red head, the 3rd inlet does not seat if it doesn't get the gas it wants. I see heat.
                        B) With my hand removed open to atmosspehere I get a PU time of 2mins 25. The thing works dandy. Runs cool, and I see 4 & 34 bar at 1st and second respectively. Quickest PU times I've ever seen. [I did not know to record these when new]

                        Whereas connected to my supply I will see PU of 3mins 30ish and low 1st & 2nd pressures. My blowby with inlet open to air sits at 10-11 l/min (about 21-22 cu foot) and only goes up to 13-14 l/min right as it tops out. I susepct my 1st stage is still a bit off. Connected to my supply I get blowby at nearly double that figure, right off the bat from start-up

                        I conclude the restriction produced heat that 'did' for my second and third stage and accounts for why my 1st stage rings had no wear, but low pressure. Previously I had checked input pressure with a Digital manometer, useless it led me astray. Previously I had already mashed parts doing htsi test and with no flowmeter I had no clue where the issue was. To further lead me astray the valves had been letting go becaue of lack of gas, creating heat. The issue just snowballed and I chased my tail.

                        Without my Rotameter flowmeter and Magnehelic along with a digital thermometer to confirm everything, I would still be floundering.

                        only a vacuum pumps produces only a fraction of the heat a compressor does.a reduced pumping rate if it is caused by low inlet pressure doesn't make more heat it makes less.
                        Flatracker, please be wrong. Oh I beg, I implore, on this occasion.... please be wrong??! If you are right I really don't see what is happening. I am ceratinly seeing heat and crazy secpond stage pressures and more blowby with even a slight restriction on my inlet. My one finger across the inlet sees the blowby go up. I mean this in the nicest way, but "Please be wrong!!".

                        The restriction is there and I strongly suspect the utility meter or regulator . Looking at this now. Proper guages got me out of this jam, and expalins why no amount of mindless part-swapping was ever going to fix it. All I was doing was mashing more parts with more heat. I will now look to the real source of the fault . I think my gas utlity co. regualtor has gone iffy. That would expalin why it 'used' to work. Standby - we will see.

                        Flatracker, if you can shoot down my logic, please fire away. Because the bit I don't get is that whilst pressure drops to below the static 2.1Kpa /21Mbar (Coltri spec 17Mb) as soon as I fire-up, I see 1.5Kpa / 15Mbar (less than Coltri 17Mbar spec) that is still better than atmosphere, and it holds fast. But my Coltri doesn't like it and gets hot preferring atmosphere?? Odd. The thing works better at atmosphere, a lower inlet pressure?? Eh?? Methane has less denstity than air but supplied at more pressure even if a babies breath pressure and below what Coltri ask for, it should be better than atmosphere???. So I may have found the fault vai the wrong diagnosis, how is my logic flawed???
                        Last edited by BritCNGUser; 05-05-2015, 07:56 AM.

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

                          Originally posted by BritCNGUser View Post
                          Karl, it is thanks to your post on flowmeters that I got to it as quickly, although far too slowly! OK, I suppose i would have found the scuba compressor forum and the thread there eventually. I have been searching interweb for this stuff, but you found it for me an d got me thinking that way. Thank you. My flowmeter is a beast of a thing. Only next door's cat knows how old the thing is, solid brass castings, and RSJ joisting for a cage. Mad it is. If you threw a modern Dwyer at me, it'd be kiss. This thing would kill.

                          Now before you all I vow, I will never ever work blind again. Especiailly when gauges can be got so blinking cheap.

                          [ATTACH=CONFIG]4972[/ATTACH]Test one: Connected to my gas supply I was gettign crazy heat, slow PU times, my Dwyer Magnehelic on inlet would drop from a static 2.1Kpa /21Mbar (Coltri spec 17Mb) to when running 1.5Kpa / 15Mbar (less than Coltri 17Mbar spec)

                          Test Two. I ran my pump open to atmosphere. my past tests with no gauges had told me nothing. Now with gauges I saw

                          A) With my hand held even slightly over the inlet to restrict sees blowby double, my second stage pressure skyrockets to 40-45 bar ( the 2nd stage gauge jumps up and down - it made the 3rd stage inlet valve let go??) and the temperatures on the 3rd & 2nd stage skyrocketed too. I now summise this caused heat and ruined my 2nd stage. Certainly with the Red head, the inlet does not seat if it doesn't get the gas it wants. I see heat.
                          B) With my hand removed open to atmosspehere I get a PU time of 2mins 25. The thing works dandy. Runs cool, and I see 4 & 34 bar at 1st and second respectively.

                          Whereas connected to my supply I will see PU of 3mins 30ish and low 1st & 2nd pressures. My blowby open to air sits at 10-11 l/min (about 21-22 cu foot) and only goes up to 13-14 l/min right as it tops out. I susepct my 1st stage is still a bit off. Connected to my supply I get blowby at nearly double that figure, right off the bat from start-up

                          I conclude the restriction produced heat that 'did' for my second and third stage and accounts for why my 1st stage rings had no wear, but low pressure. Previously I had checked input pressure with a Digital manometer, useless it led me astray. Previously I had already mashed parts doing htsi test and with no flowmeter I had no clue where the issue was. To further lead me astray the valves had been letting go becaue of lack of gas, creating heat. The issue just snowballed and I chased my tail.

                          Without my Rotameter flowmeter and Magnehelic along with a digital thermometer to confirm everything, I would still be floundering.



                          Flatracker, please be wrong. Oh I beg, I implore, on this occasion.... please be wrong??! If you are right I really don't see what is happening. I am ceratinly seeing heat and crazy secpond stage pressures and more blowby with even a slight restriction on my inlet. My one finger across the inlet sees the blowby go up. I mean this in the nicest way, but "Please be wrong!!".

                          The restriction is there and I strongly suspect the utility meter or regulator . Looking at this now. Proper guages got me out of this jam, and expalins why no amount of mindless part-swapping was ever going to fix it. All I was doing was mashing more parts with more heat. I will now look to the real source of the fault . I think my gas utlity co. regualtor has gone iffy. That would expalin why it 'used' to work. Standby - we will see.

                          Flatracker, if you can shoot down my logic, please fire away. Because the bit I don't get is that whilst pressure drops to below the static 2.1Kpa /21Mbar (Coltri spec 17Mb) as soon as I fire-up, I see 1.5Kpa / 15Mbar (less than Coltri 17Mbar spec) that is still better than atmosphere, and it holds fast. But my Coltri doesn't like it and gets hot preferring atmosphere?? Odd. The thing works better at atmosphere, a lower pressure?? Eh?? Methane has less denstity than air but supplied at more pressure even if below what Coltri ask for, it should be better than atmosphere???. So I may have found the fault but how is my logic flawed???
                          Your second stage pressure can't skyrocket from a lack of gas thats physically impossible, you still have a third stage problem, you say it gets hot what are the temperature readings?

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

                            Your second stage pressure can't skyrocket from a lack of gas thats physically impossible,
                            Agreed totally proposterous, perhaps I did not explain myself well. The 2nd stg gauge see-saws up and down when I restrict the inlet whether hooked to my gas utility or to atmosphere. That over-pressure can only be coming for as you say the 3rd stage. But when I let it have all the atmospheirce air it wants, all is dandy. No third stage issue or any other come to that. After running to 'pressure up' if I restrict the inlet I see 68-73 degs C at the 3rd stage, 55 at the third, and about 35-40 at the first (all measured on the exhaust port), higher blowby. Let it run unrestricted pulling air by PU I see all roughly even at 55-60 degs C, and lower blowby.

                            I definitely have more blowby on my first stage and there is definitely soemthign amiss with my supply. You are likely right about the 3rd stage. But I still don't have a completely rational explantaion for all I see. For cryin' out, it works to atmosphere. Unless i have a combination of issues still dogging me. Having my gas-utilty regulator looked at tomorrow, but even this bugs me, because on light load, my water heater, adn gas dryer runnign together the regulator holds pressure steady only 1Mbar below static, as it should. It only struggles when i throw the Coltri at it.
                            Last edited by BritCNGUser; 05-05-2015, 02:40 PM.

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

                              do you have any kind of surge tank on your suction

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

                                i use a 100lb propane tank for a surge tank on my suction about 30 gal, smooths out things a ton.

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