M929A2 Draining Air Tanks; One At A Time?

[gottaluvit]

M929A2. Okay, I know to drain the third down first, then fourth down, then first one, then second one down. Thing is I have been doing one at a time, and by the time I get to the third and fourth to be drained, the tanks are nearly empty. I hear something let loose two or three times (varies) when draining the first two to drain. The last two I drain are so low on pressure by the time I get to them that it would seem to me that they don't get to purge much water out. I would think you would get more water out if it hissed for a bit.


Should I just start with the proper order but let them all go at once, or am I doing it right by letting each tank drain completely? It seems as if, by me letting each of the first two drain completely, that they are in fact draining a good bit out of tanks 3 and 4 of the sequence.


Could I have an issue with some check valve? Or am I just overly concerned with nothing?

Jim

 

[Floridianson]

I would say yes to the check valves. Even with the Deuce we drain the outer tank first to check the check valve between the two.

 

[gottaluvit]

Really? Nice to know. So if the latter one being drained is already partially or fully drained by draining the first one, there is a failing check valve? I have a thread on my air issues http://www.steelsoldiers.com/showth...s-To-Build-Intermittently-Parking-Brake/page4, but didn't think at all they were related. Heck, I just thought this was normal and I was draining wrong. Screwed up again by not putting them together.


Thank you.

 

[plode]

Mine function the same as you are describing. I drain 3, then 4, and when I get to the 1st and 2nd, there isn't much air left(still a decent amount, but not as much as 3 and 4 had).
I don't ever get water out of my drains, but my air dryer purges a good amount out(wets the pavement when I let it sit idling.

 

[juanprado]

You bring up an interesting point. A few years ago, another member posted the link to all the PS army maint cartoon magazines. One bored day, I read"most" of them especially where they pertained to 5 tons.

I found 2 conflicting articles about draining the M939 air tanks. One said to completely drain and the other said partially drain till no moisture seen or felt ( something to that effect). Take it for what ever it is worth.

If you have a functioning drier with a good clean inner cartridge and a recent spin on decaissant filter, it will forgive you if you do not drain the tanks as the drier will remove the moisture till the filters are trashed. Again just my .02 to encourage driers to be serviced yearly.

 

[dawico]

You bring up an interesting point. A few years ago, another member posted the link to all the PS army maint cartoon magazines. One bored day, I read"most" of them especially where they pertained to 5 tons.

I found 2 conflicting articles about draining the M939 air tanks. One said to completely drain and the other said partially drain till no moisture seen or felt ( something to that effect). Take it for what ever it is worth.

If you have a functioning drier with a good clean inner cartridge and a recent spin on decaissant filter, it will forgive you if you do not drain the tanks as the drier will remove the moisture till the filters are trashed. Again just my .02 to encourage driers to be serviced yearly.

So if you get water out while draining the tanks then the air dryer needs attention?

I have never had even a drop come out of the tanks. I recently noticed that my dryer will let out a little moisture but I believe that is a new thing.

923a2 BTW and just curious about the moisture situation.

 

[gottaluvit]

I would say yes to the check valves. Even with the Deuce we drain the outer tank first to check the check valve between the two.

Since they're so cheap, I went ahead and ordered three to eliminate another thing toward fixing my other air issue. Thank you.

 

[gottaluvit]

So if you get water out while draining the tanks then the air dryer needs attention?

I have never had even a drop come out of the tanks. I recently noticed that my dryer will let out a little moisture but I believe that is a new thing.

923a2 BTW and just curious about the moisture situation.

Well, it's not that I am getting water but knew with hardly any air in the last two drained, if there was any it wouldn't be enough to get it all out. I am still getting a slight mist of fog from the air brake antifreeze I used to clean the system out last week. That dryer really throws some air out when it purges so I assume it is working quite well.

You got me thinking. (rare event) Before I changed out the dryer to the mrap type, there was a heck of a lot of water coming out when I drained the tanks and isn't now. Must have been a good investment.

Thanks,
Jim

 

[gottaluvit]

Well, it's not that I am getting water but knew with hardly any air in the last two drained, if there was any it wouldn't be enough to get it all out. I am still getting a slight mist of fog from the air brake antifreeze I used to clean the system out last week. That dryer really throws some air out when it purges so I assume it is working quite well.

You got me thinking. (rare event) Before I changed out the dryer to the mrap type, there was a heck of a lot of water coming out when I drained the tanks and isn't now. Must have been a good investment.

Thanks,
Jim

I meant the dryer really throws out some water. Left drops all around it's circumference and a white cloud in the air. Today was the first time I was under it when it blew off. I was happy to see it. One day I will learn to proofread before hitting the post quick reply button.

Jim

 

[WSm925a2]

Did we ever figure out why there is so little air from tanks 1 and 2 when draining, I have the same issue?

 

[gottaluvit]

You meant #s 3 & 4 right? They go from the top, 3,4,1,2. But, no, I have been cracking them right before #2 finishes so as to have enough pressure to get any water out of #s 3 & 4 that might have accumalated. Still don't really get any visible water or mist though. I had taken apart and cleaned all the check valves, which were pretty clean anyway.

 

[JohnnyBM931A2]

Honestly.. I usually just do them all at once until all the air is gone from the truck. I never have any water come out... Maybe a bit of moist air. Air dryer purges a decent amount of water when it blows. Opening all of them at once means there is plenty of air to drain all of them, at least on my truck.

 

[gottaluvit]

Honestly.. I usually just do them all at once until all the air is gone from the truck. I never have any water come out... Maybe a bit of moist air. Air dryer purges a decent amount of water when it blows. Opening all of them at once means there is plenty of air to drain all of them, at least on my truck.

I wonder why or how it could matter at all, if at all!

 

[JohnnyBM931A2]

Who knows

 

[juanprado]

The correct order from top to bottom is 3,4,1,2 That is also confusing. Some trucks are stenciled on the step bracket but not many.

I used to get water before I rebuilt the drier but I get none now. My guess is if you have water, to change the coalescent filter and the spin on decasant filter.

 

[DinoShepherd]

Very new at this game, so forgive me.

I don't think we got a definitive answer to the question of, "Is it a problem if tanks 3&4 have hardly any air left after draining 1&2?"

My truck is stenciled, so let's assume we are talking actual tank numbers and not just to bottom.

Thanks.

 

[jcollings]

Very new at this game, so forgive me.

I don't think we got a definitive answer to the question of, "Is it a problem if tanks 3&4 have hardly any air left after draining 1&2?"

My truck is stenciled, so let's assume we are talking actual tank numbers and not just to bottom.

Thanks.

Has anyone changed the drain valves to a different style? Mine tend to leak a little if I don't use a tool to snug closed.

Thanks