Mrodair Airmax Compressor Review: Prep, Poor Build Quality, Fixes, Ultimately Unsafe for Use
For those working on their MrodAir Airmax Extreme compressor, this thread is both a resource and report of my own experience. Work on my compressor evolved over time. Initially, the focus was preparing the compressor for a longer life, easier maintenance scheduling, and safer operation. As issues were discovered, this devolved into troubleshooting, fixes, and currently finding my compressor unsafe to use until an oil-in-air problem fix is found at Mrodair.
You can follow my journey beginning in October last year http://www.talonairgun.com/forum/viewtopic.php?f=52&t=33430
This thread is that Guinea Pig thread’s more useful successor.
The first few posts in this thread cover major topics. The major topic posts continually undergo editing to keep information up to date. They do not attempt to preserve chronology. Posts after the major topics are chronologic, just as in any normal thread.
NB. Changes in the major topic posts are not flagged as new by the BBS system.
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Disclaimer: Material presented here may be incomplete or inaccurate.
Work you undertake on a compressor is expressly at your own risk.
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Introduction
I pre-ordered my Airmax compressor from MrodAir after watching their product introduction video and reading the website. My impression was that the compressor would be a mid-priced, mid-performance machine suitable for my limited, single shooter needs. The promise that a US outfit would be going over the units and making sure they worked was reassuring. With its advertised “silicon bronze rings”, “3 cylinders”, and real pistons, this seemed a happy medium between an o-ring based compressor and the “overkill” of a dive compressor.
We were reassured by MrodAir that each unit would be tested and that they had arranged many upgrades. These compressors would be long lasting, “real deal” compressors. As an airgun newbie, I was unfamiliar with MrodAir. There were some negative online reviews, but I also know that online reviews often trend towards the negative – even unfairly. I took a chance, ordered a compressor, and promised to report my experience on this forum.
My desire was a compressor that would let me fill or top up a tank reliably. I was only a single shooter, but the convenience of ready air was enticing. Also, the ability to use high air consuming items, like regulator testers, made a compressor/tank combo a nice step up from hand pumping.
My experience has not been consistent with a ready to go, fully developed product. Others have fared both better and worse than I. There are issues potential buyers should know before purchase.
False Advertising
There were factual inaccuracies in the product advertising at MrodAir. These incorrect details affected my decision to place an order. Had they been accurate, I might not have placed an order.
As described on the product page when I ordered the machine…
No, this is a TWO stage compressor. Only two cylinders do actual compression. Although the 2nd stage piston rides atop a carrier piston, that carrier piston does zero compression work. It is drilled through and lacks air inlet or outlet. It is simply not a compression cylinder. The compressor can still achieve 4500 psi by making the two stages work harder, but the 3 cylinder count is a factual error. I am only counting cylinders that perform compression. Otherwise, one could lash a six-pack of beer to the compressor and dub it a 9 cylinder compressor. Two cylinders means each must do more work than in a three stage machine. There is also less chance for interstage cooling of the compressed air.
Silicon bronze piston rings were prominently mentioned as a feature of the compressor. This gave the impression that rebuild intervals would be consistent with that of metal piston rings. I was surprised to find my 2nd stage piston rings were not metallic. The rings resisting the greatest heat and pressure, are polymer
Several other owners confirmed that the high pressure cylinder rings. I informed MrodAir and the initial reaction was that I was wrong. Their website continued to advertise these compressors as having silicon bronze rings for several days more.
Piston ring description was adjusted as of 4/22/2016. The high pressure rings are now described as silicon bronze suspended in phenolic resin and the low pressure rings as traditional cast iron. The number of cylinders advertised remains three.
Because the 2nd stage rings are now known to be a less durable material than silicon bronze, having replacements is even more important. The high pressure rings look like angle cut wear rings. They are soft and easily indent with a fingernail. Heat, flame and smell testing of one from my compressor makes me think these are actually silicon bronze filled PTFE wear rings. I would like to find a second source. I have yet to find a source for bronze filled phenolic resin rings, but silicon bronze filled PTFE wear rings do exist.
Durability and duty cycle should be scaled back in your mind. Filling a 88 cf tank in one session stresses the compressor to its limit. A reasonable expectation would be to top off a tank once in a while or fill a gun directly. Long term torture testing suggests 20 minute max run times. http://www.gatewaytoairguns.org/GTA/index.php?topic=107945.0
Technically, the compressors are 120 volt units, but they need a 30 amp service outlet to run properly. A 20 amp circuit is insufficient. My own unit draws about 24-27 amps during operation. It is simply too large a current draw to safely run on a 20 amp circuit. Perhaps one could get away with it for filling a gun directly, but topping or filling a tank is asking a lot of a 20 amp circuit.
Electrical Hazard
My unit arrived with two major electrical components (relay and contactor) hanging loose. Each was held in place only by the wires connected to them. A consumer who receives the machine reasonably expects safe and secure wiring. If your unit arrives in the state mine did, disaster will happen in short order.
The compressor is not grounded. Grounding pin of its AC power socket is connected to ….. nothing. This machine has a semi-open, metal frame, uses water for cooling, and is not grounded.
An under capacity 15 amp IEC receptacle connects the AC power cord to the compressor. The IEC connector is only 15 amp rated, well below the actual current draw of the compressor. The IEC power connector can overheat or starve the machine of adequate power.
Electrical wring skills can correct these shortcomings. It is doable, but for a vetted design and build, the average buyer should not need to do electrical rework.
Air Quality with Heavy Oil Contamination, (Critical Go/No Go Safety Item)
My unit, and that of some other owners, continually passes oil from the crankcase into the low pressure cylinder. Oil that gets into the air path oxidizes (maybe even diesels) at the high pressure cylinder, fouling that cylinder’s rings and valves. The remaining oil goes on to the water separator and MUST be filtered out before it reaches a gun or tank. A little oil is not uncommon for a compressor, but it must be removed with a filter before it gets into your tank or gun. My unit splatters oil all about in the low pressure cylinder. Bleeding the separator filled my garage with suspended oil vapor. Not all units have this problem. Mine does and so do some other owner’s. This is distinct from being shipped with oil in the crankcase. It’s actively putting more oil into the cylinder with each stroke.
This oiling issue should be tested before one puts the compressor into use. An affected compressor will still fill a tank. Merely testing whether the compressor will fill a tank is insufficient. You should disconnect the air output of the 1st stage and specifically check for continued oil output before you try a pressurized run. Without my large, Alpha filter, this would have been an oil in the tank disaster. With my Alpha, it is still a problem. A filter can only handle do so much. Filters are meant to deal with the the last traces of oil, not heavy contamination. Oil in your high pressure air system is an explosion hazard and may negatively affect seals in your guns.
Summary
There are indeed MrodAir upgrades like the automatic cutoff gauge and radiator. Those are useful, but one needs to go over these units carefully before use. Expect to do electrical and mechanical work to keep them running. Mine, as delivered, was neither turnkey nor ready to use. Ultimately, mine had such severe oil contamination issues that it was unusable and no fix was forthcoming from Mrodair. On the up side, the compressor is easy to tear down and work upon. If good parts were available, and fixes developed, one could conceivably keep a unit running until one could afford a more robust solution. Just anticipate needing your mechanical and electrical skills.
The compressor does fill fast – perhaps too fast for its own good, Takes about 80-90 minutes to fill a Great White from empty to 4500 that’s with frequent bleeding. It’s just a tad over 1 CFM. You can actually see the pressure gauge of a Great White move as the compressor works. However, there are reliability, longevity, duty cycle, and oil contamination issues that need working through. I never got mine sorted after months of patient work.
My story follows. You will learn about initial inspection, electrical, air leaks, oil in air contamination, and blowouts. There is even a down trodden me “throwing in the towel” and ready to scrap the machine after first discovering heavy oil contamination and suffering another o-ring blowout while filling a tank.
I think one might get this compressor to marginally work directly filling a gun or a small cylinder, but expect very slow to no customer support if you encounter real issues. This is a machine built to the barest margins possible to still run. It has no pressure safety releases and should not be run more than 15 – 20 minutes at a time. You need electrical and mechanical skills to keep things in good order. This is of course, if you get a good unit in the first place. Test thoroughly when it arrives. You are the factory’s last quality control step.
Guy
Main Topic Posts Index
30 amp 120 volt RV service outlet Installation.
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357139
Delivered Components
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357140
Initial Inspection
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357141
inspection of cylinders for oil seepage during shipment
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357142
Opening Crank Case for Complete Oil Change (No, not for routine changes!)
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357143
Electrical Fixes and Upgrades
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357145
High Pressure Valve and Water Separator
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357146
Automatic Pressure Switch Gauge Glycerin
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357147
Water Cooling System
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635#p357148
Piston and Piston Ring Measurements
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635&start=60#p359151
O-ring Sizes
http://www.talonairgun.com/forum/viewtopic.php?f=52&t=34635&start=40#p358769
Latest changes
5/21/2016
No Mrodair fix for the oil in air contamination issues. Lower pressure cylinder consumes oil severely. Small engine shop evaluation suggested piston and cylinder tolerance are too large to ever effect a seal. Without a way to fix that problem, the compressor is unsafe to use. My unit is now going to another victim/owner for use as a parts donor.
If you are contemplating this compressor… my painfully earned advice is to buy from a different dealer and get a Shoebox or save up for a full scale dive compressor. The Mrodair Airmax Extreme compressor is a poor quality product you will most likely regret.
All Replies
I had the same oil problem as Guy, oil in both cylinders. I worked on it 3 weeks but never got as far in as Guy. After the third week I sent mine back. my second one works but I only fill one 90ci tank with it. I change out the dessiscant in the moisture separator every time I fill my tank. I don’t taste any compressor oil in the moisture I pull off during filling yet. I’ve got 220 min. Run time on mine so far.
How many hours have you put on yours?
Any problems at all?
How much oil comes out when you bleed the air, or clean the filter?
Inquiring minds want to know…..
BTW – I’ve seen 13 different guys posting that they have the compressor and at least 4 of them have been having problems…….over 30%, and I bet there are guys out there with them that have yet to use them.
IF Guyko was the only one having trouble why would MRod air already be looking at different rings and such? Preventative measures? Not
I would be taking it apart and cleaning it after every fill to make sure you know how much water/oil is getting thru.
I wonder where the other 48 airmax compressors purchasers are? (I got one) I guess they are using theirs and having no problems (yet?). Are they just lucky that they didn’t get a lemon like guyko did. Crossing my fingers and hoping that my guns or air tank won’t explode in my face.
Good on Guykuo for all his efforts! Hopefully he has saved some one the hassle headache and expense of this compressor.
Seems to me Mrodair owes him (much more than he paid for the compressor) for al the R and D work and diagnostics.
Perhaps a coordinated email campaign to tell them so?
“Abortion MAX Air”
We are MRod Go FUCK YOURSELF Air
Anyone else wonder why Mrod Air has nothing for Mrods? Did they screw over so many people they need to keep finding new suckers to prey upon?
We know he got bitch slapped for stealing WOKS design and the word is R&L and Maddog Stocks would like to see him strung up for some bullshit he put them through.
I hope no one who got one of these AbortionMax Compressors gets oil in their pcp airgun and blows it the fuck up!
Radio silence….. If you have a bad problem like mine did, you definitely get the sense you are not any sort of priority.
This is no small amount of harm that comes from selling this abortion of a compressor. It doesn’t produce good quality air, lacks pressure safety reliefs, and exposes the user to electrical & high pressure air risks. It’s sold as capable of filling tanks, but really can’t do so without destroying itself. The poor souls who spend considerable amounts of money getting even the base unit are losing the ability to afford better solutions. Bringing this to market is a disservice to the airgunning community. Even if you manage to return a bad unit, you’re still out shipping in two directions and face a restock fee. Once, you make the mistake of placing an order, you are locked into taking a loss.
I’m super lucky getting to bail out to a Bauer. A lot of other victims are going to be less fortunate. I am unhappy about my situation, but we can all be :angrymob: about how this turns out for most.
I told you he has no plan of fixing them. He is just a peddler of Chinese junk that he charges a premium for.
Answered a question on the yellow today but didn’t answer the one about where are the Hubens from a couple of days ago.
Shipped it down to Michael McKeown so he can use it for spare parts. At least it might do someone some good for him, and I don’t have to worry about someone else hurting themselves trying to use the unit.
This is the happiest I have been about my Airmax compressor since the day it arrived.
Celebrated with a good bourbon & ribs.
So I guess “Brother, we are MRodAir” never got back to you? Sad, sad indeed
Took them to be surface ground to the proper thickness.
The std rings available were a bit too thick so Monday I’m going to a friends shop and pick em up.
They look much nicer than the OEM for sure.
Testing the scarf cut this weekend.
They are actually hyd sealing rings and should control oil the best.
I’ll let you know.
Thanks
We Are Mrodair
Arranged a more positive end to my Airmax journey than cutting it up as scrap metal.
Donated mine to Michael McKeown so he can use it for spare parts. At least it might do someone some good for him, and I don’t have to worry about someone else hurting themselves trying to use the unit.
This is the happiest I have been about my Airmax compressor since the day it arrived.
Celebrated with a good bourbon & ribs.
He’s trying peddle 50 more MK ll compressors. I have a feeling he will not fix any of the first compressors that he sold. Will just blame the customer for miss use.
Unless they knew these things had serious problems already, there is no way they fixed all the problems that fast with any long term testing.
Thanks for the drilling speed recommendation Dyotat100. I did say I’m a gunstock carver not a machinist :-), and true enough I was turning much faster than that. I don’t have a back gear on my mill so I don’t think I can get down that low anyway. The steel I ordered yesterday is 303 stainless which is supposed to be much easier to machine than the 304 I had been using. I will however set the belts on the milling machine to the slowest speed it can do, so thanks for the advice.
Mrodair at one point told me that if I was spending more than a few bucks on the larger reed valve plate I was spending too much because that’s how much it would cost to have it made in China. If that was the case I sure wish he would have had them made. If he’d had them made (and I shared with him the solution) he could have had one made for each of us 50 early adopters for under a couple hundred bucks. He could have doubled his money charging us $10 and no one would have complained. ‘Course, I don’t believe the ‘few dollars’ quote anyway. I would very much have preferred to buy it than to have to learn how to make it! The original reed valve plate has two problems. One, the large air hole is too large and the reed valve barely covers it and I believe is the cause of some compressors that experienced wide pressure needle swings while failing to build pressure: the reed valve barely covers the hole and only if it hangs perfectly. And, the plate is not wide enough such that there is too little gasket area in the spot it likes to blow out the gasket at. I drew the reed valve plate to be wider, a slightly smaller diameter main air hole, and I moved the hole up a little bit to get it away from the tapered bottom part of the reed valve a little bit.
To follow up with bray115, thanks for your further comments, and my writing on my web site that the Airmax will be “pretty much like a Bauer” is preceded by the comment that when “in a good condition of reliability and clean air” it will provide “pretty much” the same capability. By good condition of reliability I meant all the cheap o-rings changed out, intake filter added, and the reed valve plate changed so it’s gasket won’t blow out. By clean air I meant after adding a quality post compressing filter the same as has to be done with a Shoebox. My point is that whether a Shoebox or an Airmax, everyone adds either a Joe B. filter, a Diablo, or the filter the fellow on this forum sells (Jaime Lavallee) which I’m on the waiting list for and just this morning got an email that they will be ready tomorrow. I have not addressed oil consumption as Guy’s is the only compressor I know of that has had the excessive oil consumption issue, and if it has to do with excessive clearance between the cylinder and the piston, there’s sure not a lot that can be done about that. Mine is apart right now while I’m making parts for this other fellow, so I plan to measure my machine’s piston/cylinder clearance this afternoon. Based on some research I’ve done I think .006″ is about max clearance.
Personally, my position on owning this thing is I, like Guy, have spent an insane amount of hours and money to get it to the point I think it will provide me with fast clean air (as soon as I receive the canister filter that is). I hope and pray that I get forty or fifty fills out of it which should take me through the rest of my argunning life. I mean, I just need enough air to get sighted in and practiced up for turkey season twice a year. And honestly, I do think short of throwing a rod through the crankcase I will indeed get those forty fills. That would be about 7 hours run time. Absolutely no way it could survive a dive shop’s daily use like a Bauer, but it does provide fast clean air (with an added filter…no different than a Shoebox needs) “pretty much the same” as a Bauer provides. So to make what I ‘meant’ more clear, I added some language to my web page…which page frankly won’t last much longer ’cause it’s embarrassing to admit that I couldn’t afford a Bauer or an Airtex and chose to go with the gamble of cheap Chinese crap…but I digress…here’s the language I added to the comment you correctly faulted:
“Figure a Shoebox by the time you’re done adding on everything you really need to operate you’re at about $1700. By the time an Airmax is in a similar condition of reliability (Airmax has to have all it’s cheap orings changed out, intake filter added, and reed valve plate gasket issue fixed) and clean air (with both the Shoebox and the Airmax additional post compression filtration must be added), you’ll be at about the same price. You’ll still be two grand less than a Bauer, and you’ll have pretty much the same capability in terms of clean air and fill time, but certainly not with a Bauer’s longevity. If you’re like me and only need to top off a tank a couple times a year, it should last a long time. If you need to be doing lots of fills, save your money for a Bauer. If your machine happens to be one that burns excessive amounts of oil due to too large a piston/cylinder gap, there’s nothing I know of that can be done.”
Is that better? And if not, I’d rather just take the whole thing down. I need to maintain a good reputation for my gunstock carving gig and not get sidetracked with some piece of crap equipment giving me negative posts online. While I was at it I removed information about the Peltier I added to the moisture separator. It was a cool idea (pun intended) but 7 watts of heat removal is nothing compared to the ~2500 watts of heat generation.
The thing I really regret is there is zero hope of selling the thing. Those of us that own one either need to make it work good enough for our needs or if it craps out like Guy’s did chalk it up to a thousand dollar mistake. Which sucks. I don’t think any of us are in a happy place with the thing.
In the next hour or so I’ll get the new head and reed valve plate drawings up. I much prefer to give away the drawings and o-ring sizes so people can do the upgrades on their own than pretending to be a machinist making the parts. I am absolutely not interested in being a machinist or in having my name associated with the Airmax compressor beyond being a trusting sucker that had to learn a tough lesson the hard way and just want to share what I learned with the few other poor guys that went the cheap route. When did a thousand bucks become the ‘cheap’ route?
I highly doubt we will see any more of these compressors come on the market, so once the fifty or so of us that have one get ’em fixed up enough to work (or thrown away) I can take the page down. Mrodair has told me at different times “we have fifty of them in operation with no problems”, “we have a hundred of them in operation with no problems”. I’ve heard of maybe 6 in operation, and they all had problems. I can say though right now I am getting fast fills. One day on accident I let the machine deadhead and it hit 8,000 psi (that was scary). When I get the canister filter from our fellow forum member I’ll have clean air.
How long will the bearing-less connecting rods last? Who knows. I can say I called two small engine repair shops this morning and they said it is common that inexpensive small engines have no bearings on the connecting rods at the crank; just machined aluminum. So maybe it’ll last as long as the typical inexpensive yard equipment motor. Not terribly long, but long enough for me. I hope.
The next journey is to find a source for the high and low pressure rings. I do not for a minute think the Chinese factory making these compressors is making their own piston rings. I see images online of rings that look just like our high pressure rings, so I’m sure they must be a commercial product, and similarly the low pressure rings must be a standard part. I have asked Mrodair multiple times for either a spare set of rings or the information by which I can go get buy them somewhere and he always manages to answer other questions than the one I asked, so once again we’re on our own.
Michael McKeown
Send it to me and I will put it out at 25 yds and shoot it with my .308 condor to put it out of its misery
I will buy parts if you want to part it out lol
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Miksatx, I’m glad you discovered the oil problem soon enough to get it swapped out. I had fallen ill when mine arrived. A great deal of time had passed by the time I reached first power up.
If you get this machine, test it out right away for the oil issue. That is one problem you can’t work around safely. If you are lucky to get one that doesn’t consume oil, treat it gently and limit run times. It’s not a robust machine.