Compressor Rebuilt Service - Bad Odor n Poor Pressure

[UaVaj]

compressor is a MaxAir 35 w/ Honda gas. 80 hours on the meter. oil change 10hr, 25hr, 50hr, 75hr with Seco Lube Synthetic 500. filling HP120 to 3500psi with 21%. 2-4 tank per session. each fill session 4-6 weeks apart.

on the last fill session (mid june) the compressor has been unable to maintain pressure. first two tank went normal. on the third tank it bearly held 3500psi. on the fourth tank it bearly held 2400psi.

of the last 5 tank - the air has a "burnt oil odor" to it. last 5, because did noticed one of the tank from the last last fill session (mid may) had an faint odor to it. that tank was breatheable, however definitely not normal. did not dawn on me something was wrong right away.

took the short fillled tank (2400psi) from the last fill session for a dive. at depth, the ordor was so bad, caused excessive coughing. had to resort to pony (which was filled a few months back) to get back to surface. back at the house. test smelled the other 3 tank from the same fill session. all have the same strong odor.

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what could be wrong with the compressor? what could be causing such ordor?

where in southeast florida can this be serviced?

 

[Cleavitt]

It sounds like you had a close call. Bad breathing gas is scary stuff. I'm glad you had the presence of mind and were able to safely abort the dive. It's very possible for contaminated gas to turn a person stupid so fast that they never have a chance to realize there is a problem. My personal theory is that a lot of those "narced" divers that have just swam into the abyss never to be seen again were actually the victims of contaminated gas.

It seems as though your compressor has a pretty significant mechanical issue. It probably needs a pro to look at it in person. I don't have any recommendations for a compressor expert, but I'm sure someone else does. Best of luck getting your compressor back in safe working condition.

 

[rcontrera]

Sounds like you need to do your 100 hour service a little early. The 100 hour kit has the 2nd, 3rd and 4th stage valves. If the valves are not closing properly, the pistons will just thrash at the air and cause over heating.

 

[UaVaj]

rcontrera.

just to reaffirm. so the symptoms on post #1 matches the 100hr service? is such symptom "the classic symptom" of the 100hr service?

the poor pressure sounds to be correct with the valves not closing properly. what about the ordor? is that from the air thrashing, then heating, then buring the oil?

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given the issues with this mch6 (portable). are the larger mch13 or mch16 (semi-portable) any better? or is this just part of the breathing air compressor maintaince and no way around it?

 

[Cleavitt]

what about the ordor? is that from the air thrashing, then heating, then buring the oil?

That sounds about right. The fact that the contaminants made it into your tanks means the filters are shot. You will need to replace the filter cartridge(s) before you can pump air again. Out of curiosity, how many hours of runtime have the current filters been in use? Even if they were in fairly new condition, the recent mechanical problems could cause excessive heat, oil, and vapors (perhaps from overheated oil) to quickly overwhelm the filters.

 

[rcontrera]

No ... there really isn't a classic symptom for the 100 hour service kit other than the hour meter reaching 100.

If valves do not close properly, air can back flow through the system. A third stage piston can pump higher pressure into a second stage or even first stage piston than the piston is designed to handle. The resulting added stress causes a HUGE amount of heat on the related bearings. It doesn't take long before the oil is cooked and the result is a breakdown in parts. Valve leakage can damage ANY compressor so proper maintenance is essential.

Now ... all that said ... your filter system should have told you a LOT earlier that there was a problem. The separator stack drain fluid is a pretty good indicator of the health of the compressor. There is always a little oil that is blown out with the water. That should be a creamy tan color and have little or no odor. Darkening of the fluid or a change in odor is an indication that something is happening inside.

You mentioned that you detected an odor several tanks ago. At that point you should have pulled your filter cartridge and inspected it. Oil on the outside of the cartridge is normal if a light film but heavy drips indicate a need to blow down more often. But, most important is that you can see the condition of the chemicals in the cartridge (unless you have one of those awful European black cartridges). There is an indicator on the side that will show the condition of the MS.

Change your valves, oil and filters and give it a go. Hopefully, that will take care of your problem.

 

[Herb-alaska]

No ... there really isn't a classic symptom for the 100 hour service kit other than the hour meter reaching 100.

If valves do not close properly, air can back flow through the system. A third stage piston can pump higher pressure into a second stage or even first stage piston than the piston is designed to handle. The resulting added stress causes a HUGE amount of heat on the related bearings. It doesn't take long before the oil is cooked and the result is a breakdown in parts. Valve leakage can damage ANY compressor so proper maintenance is essential.

Now ... all that said ... your filter system should have told you a LOT earlier that there was a problem. The separator stack drain fluid is a pretty good indicator of the health of the compressor. There is always a little oil that is blown out with the water. That should be a creamy tan color and have little or no odor. Darkening of the fluid or a change in odor is an indication that something is happening inside.

You mentioned that you detected an odor several tanks ago. At that point you should have pulled your filter cartridge and inspected it. Oil on the outside of the cartridge is normal if a light film but heavy drips indicate a need to blow down more often. But, most important is that you can see the condition of the chemicals in the cartridge (unless you have one of those awful European black cartridges). There is an indicator on the side that will show the condition of the MS.

Change your valves, oil and filters and give it a go. Hopefully, that will take care of your problem.

Ray I have this same compressor and just hit 35 hours and this post was a wake up to me about the 100 hour maint. required. Can you tell me how difficult it is for a reasonably mechanical person to complete the 100 hour service.

Thanks
a happy max air 35 customer in Alaska with no local service available.

 

[rcontrera]

Service is pretty simple. Change the oil every 25 hours or once a year ... whichever comes first, change the filter every 25-40 fills (depending on local humidity), change the inlet filter as needed (every couple of years unless in a dusty area).

The 100 hour kit is actually pretty simple for anyone that knows how to operate a wrench. It is much easier to do on a workbench than it is on the base plate so that requires pulling it off the mount. Each head comes off to expose the valves and copper gaskets for the 2nd, 3rd and 4th stages. The first stage valve set is carbon fiber so usually only needs to be replaced at 500 hours or when exposed to a high amount of oil, high pressure (bleed from 2nd or 3rd stage) or high temperature.

Be aware that in 2008, Coltri changed the inter and after cooler piping ends from JIC to standard compression fittings. The 4th stage head is also a valve seat so installation of a 100 hour kit may require updating the 4th stage after cooler piping. Again ... easy peasy!

 

[UaVaj]

for clarification.
the last last fill session (mid may) was four tank. only one of the tank had a slight odor.
the last fill session (mid june) was also four tank. only the short filled tank was used to dove. the three other full tanks have not been dove. all have the same odor.

cleavitt - filter was recently change on the mid may fill session. so 7.5 tank total fill.

ray - thanks for your insight. greatly appreciated.
btw. do you sell these 100hr service kit? if so - how much (with shipping to south florida)? still deciding to have it professional serviced or DIY (a walkthrough youtube video would be helpful).
also. are the larger mch13 or mch16 (semi-portable) any better? since those compressor are larger so hopefully with larger parts. are those larger compressor better in the maintenance and reliability category?

 

[rcontrera]

The 100 hour kit has the 2nd, 3rd and 4th stage valve plates, springs, seats, gaskets and the 4th stage head. It also includes the inlet filter, drain valve seats and the relief valve seat. It is about "two-fity".

The 500 hour kit also includes the first stage valve plate and carbon fiber valves, plus the first stage head gaskets and it's another "fity". You can figure on about $15-20 for shipping.

If you can read a schematic and operate a crescent wrench, you should be able to change the valves. There are videos at Aerotecnica Coltri - Video that cover the MCH6, but nothing for just the valves.

As for if the MCH13/16 is a better choice ... that really depends on the user. Those are both continuous duty machines ... the MCH6 isn't. The MCH13 pumps roughly twice the air as the MCH6 so it's wear and tear will be a LOT less for the same amount of fills.

I am a big fan of the 13 for home fill stations. It is big enough to handle as many bulk bottles as you need, fast enough to fill a tank in about ten minutes, is built on the MCH16 frame with smaller first and second stage pistons plus it runs slower and cooler so it really lasts a LOT longer!

The drawback is that the MCH6 is only about $3500 while the MCH13 is about $7000 (new prices)!