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
This must be the new and improved MKll. I see nothing has changed. If they were tested why doesn’t the compressor work when customer gets it. Thing is dented up from shipping I see also.
Best thing you can do is return it. The guy is a junk peddler.
mine does this all the time, it is a air leak. use the soap/water to find it. it will only leak at say 3500 but seals at 3499. I see they changed a few things on the compressor. your reed valve is facing the piston before the cover plate mine is on top of the cover plate. the water pump has a push fitting mine I had to glue. yours has dowty washers mine came with washers.
With it capped off like that, the pressure should be 4500 in under five minutes. You have a leaky valve or fitting.
I’m not Mrodair technical support. Your first and best option is to call Mike Esch and have him walk you through fixing the issue.
I will give you some general troubleshooting info based on what I know about the unit….
Since iit doesn’t leak after shut off, the leak isn’t anywhere from the high pressure output poppet all the way to the hose cap. The problem has to be earlier in the sequence.
Start with the easiest…While running, do a soapy water test for leaks on the ends of the pipe from 1st stage to 2nd stage. Fix any leak you see there.
Then it gets to be more work tracking down the problem.
Based on your photos, it looks like your 1st stage input reed valve is well centered. Did you clean it while it was apart? You removed that bit of RTV to free the valve. Good.
I don’t see a ton of oil in your low side (good). Check the seal of the gasket between the valve plate and cylinder (where that RTV layer is). Make sure you actually are getting a good seal there. There is also a low pressure output reed valve on the other side of the valve plate. It is under the little curved metal piece that is attached to the valve plate. Make sure that reed valve is also aligned and seating correctly.
Low pressure output poppets looked ok. Check its seat for debris that is preventing it from sealing.
Since you have no leak while pressurized for 30 minutes and compressor off, your high pressure output poppet is OK, but the problem could be the input reed valve or the piston rings. I’m thinking the 2nd stage is probably not where your problem is. Verify 1st stage first. The 2nd stage work is higher risk.
Check 2nd stage reed valve wafer and its seat are clean?
Lastly, (and I mean lastly because it is easy to ruin your precious high pressure rings putting the cylinder on) check the high pressure cylinder rings. When putting high pressure cylinder back on, have the piston extended out so you can compress the rings with your fingers as they engage the cylinder.
Good luck.
BTW, once you confirm ability to pressurize, get a real filter/dryer to go between this compressor and your equipment. Without a dessicant unit, a water separator like on the airmax won’t remove enough moisture to keep your your equipment dry. At best, a water separator can only produce 100% water saturated air at the temperature and pressure of the separator. Since, your equipment is going to be cooler than that temperature, that output air will release water as it cools. It is simple physics. Get desiccant between the output of the compressor’s water separator and your equipment. Ideally, you also put hydrocarbon removal after the desiccant. A good cartridge filter is now only about $200 —- a very good thing if you want to protect your tanks and guns.
I purchased one these compressors before reading anything. I guess I’m always optimistic about something I read and If I feel good about it, I purchase it. This may be one big lesson for me. My first test was to check for air leaks. With the fill hose capped I started the water pump then turned on the compressor. It started building pressure steadily up to 3100psi. After running the compressor about 20mins, the needle did not go beyond 3300psi. I stopped and did not bleed the pressure for about 30mins to see if there were any leaks. No leaks. I bled the air slowly to see if there were any moisture coming out. No moisture. I checked the poppets on both low and high side. The low side looked dirty but not bad. The high side looked fairly clean. When checking the reed valve, there was a small patch of silicone but was removed soon after. The low side cylinder looked fairly clean. Photos of these are all in my photo bucket below. After reassembly, I did the same pressure test a few more times, and each time the pressure builds but stops at a lower psi each time. Note the temperature never exceeded 50degC. Please note, Im a total newb when it comes to compressors and Im reaching out to you guys to see know why it will not build pressure.
I always check back when I see someone has posted. My compressor is still chugging away. Still just using it on my 90ci bottle.
I’m on the list for a new filter setup from Jaime.
Haha…good point!
Maybe it’s nimrodair guys looking how to fix their crappy product, you made a manual for them.
A lot of readings in this thread the last 24 hours, but we haven’t posted anything in a while. Interesting speculating who is marching through.
Heard from a friend that was talking to a guy that got ripped off on some compressor deal. Wasn’t a airmax. He contacted the district attorney. They said if he wasn’t out of state he could get in line with the rest of the complaints.
The guy is just plain bad news
Where is all the great customer service he promises over and over again?
It’s Racing Season……brother
:angrymob: Mrodair——->>>>>
Where is all the great customer service he promises over and over again?
It’s Racing Season……brother
This is getting ridiculous.
Where is all the great customer service he promises over and over again?
The BBB is not the law, they are a private company. If enough people file claims and they don’t respond or resolve the claim they will get a poor rating which will deter others from buying from them. All they do is mail a letter with your complaint and tell them to respond.
Step one in a class action case
The BBB is not the law, they are a private company. If enough people file claims and they don’t respond or resolve the claim they will get a poor rating which will deter others from buying from them. All they do is mail a letter with your complaint and tell them to respond.
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Best thing you can do is return it. The guy is a junk peddler.
X2 ! If it doesn’t reach the pressure it’s defective so don’t go for the 15% re-stocking fee. The guy is a scammer!