Excessive moisture while draining air tanks

[bneukam]

Hello Everyone,
After my recent trip went to put the mh back in storage. I always drain the air tanks, and this time there was about 1/4 cup of water that came out of one line. Not sure what line it is, but there is three under my front drivers bumper. It was the one closest to the passenger side. It was the first one that I drained.

I did replace the air drier about three months ago.

Should I be concerned about this?

Thanks

[twinboat]

You should check a few things.

Is the air dryer blowing off every time the compressor reachs 120 or 130 lbs ? If not, it may be malfuntioning.

Is it holding pressure while parked, engine at idle, for 1/2 an hour or more ? Could have a leak in the system.

Is it unloading repeatedly every minute or so ? That is also a sign of leakage.

First place to look for leak, is near the dryer, being that's where the work was last done.

[bneukam]

Everything is working as normal. Purges just before 130psi. At idle it may purge every 5 min or longer. Sitting for a week it drops to around 90 psi.

They had installed a rebuilt Meritor instead of a new Bendix. I was told that they are identical. With the original Bendix that was 14 years old I never had any evidence of moisture.

[twinboat]

It really shouldn't purge at all if not using any air while ideling.

Every 5 minutes means a leak. The gauges you see are for 2 tanks.

There is a third tank called the wet tank that all of the compressed air goes to, right after the air dryer.

If that tank is losing pressure it will make the compressor cycle over and over like yours is doing. It is the tank that controls the govorner and air dryer.

Every cycle squeezes more moisture out of the air. Constant cycling will overload the air dryer.

Re-check all of the connections on the air dryer, especially the small one that controls it. A leak in it will cause your problem.

[bneukam]

Twinboat,
Thanks for your help, I am here at the truck center that installed the drier.

I'll keep you posted on what they find


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[bneukam]

They didn't find any leaks. So they changed out the air dryer from a remanufactured Meritor to a remanufactured Bendix.

These two look completely identical but they do make a different purging noise, and the Bendix is purging less at idle. Meritor was going off every 4 to 5 min at idle, and after the switch I waited 10 min, and the Bendix had not gone off yet.

So I guess leason learned don't always go cheaper as the Meritor was 175.00 less.

Thanks twin boat for your responses, and as far as that goes thanks to all you senior members out there. For us beginners your help and info is priceless.

[bneukam]

Well shortly after the exchange of air driers the issue came back again. Its purging way too often at idle. It has no set time, it can be every 5 min or even a minute between cycles.

After looking myself I took it to a different shop, and they spent hours looking for the leak with no luck.

I have also just noticed the gauges in the coach are running farther apart then normal. The orange needle stays at 130 psi, and the green sits around 120, and drops about 3 psi when applying brakes. The orange one does not move at all when driving. Seems this is different as the orange and green used to run closer together. I am thinking this may be related to my problem with over purging.

Thanks

[DMTTRANSPORT]

Originally Posted by twinboat

You should check a few things.

Is the air dryer blowing off every time the compressor reachs 120 or 130 lbs ? If not, it may be malfuntioning.

Is it holding pressure while parked, engine at idle, for 1/2 an hour or more ? Could have a leak in the system.

Is it unloading repeatedly every minute or so ? That is also a sign of leakage.

First place to look for leak, is near the dryer, being that's where the work was last done.

...or a bad governer or the unloader in the compressor...

[DMTTRANSPORT]

Originally Posted by twinboat

It really shouldn't purge at all if not using any air while ideling.

Every 5 minutes means a leak. The gauges you see are for 2 tanks.

There is a third tank called the wet tank that all of the compressed air goes to, right after the air dryer.

If that tank is losing pressure it will make the compressor cycle over and over like yours is doing. It is the tank that controls the govorner and air dryer.

Every cycle squeezes more moisture out of the air. Constant cycling will overload the air dryer.

Re-check all of the connections on the air dryer, especially the small one that controls it. A leak in it will cause your problem.

It will not overload the air dryer, it will wear it and the air compressor out faster.

[bneukam]

They also checked out everything including the governor. Everything is working as it should.

What balances the pressure between the two tanks?


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[bneukam]

Just got off the phone with Bendix, told them my symptoms, and they said that there should be check valves in the lines after the air dryer. If these get dirty it can cause my issues


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[DMTTRANSPORT]

Originally Posted by bneukam

Just got off the phone with Bendix, told them my symptoms, and they said that there should be check valves in the lines after the air dryer. If these get dirty it can cause my issues


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Honestly never herd of check valves in the air lines themselves, but yes in the air dryer, not saying this is your issue, but, I just finished chasing an air leak for 3 weeks causing the air dryer/compressor to cycle every 2 miles, many bottles of soap water later...it was the Horton Air hub that runs the fan (you may or may not have one) the reason it was so hard to find is that when you shut the engine off the fan locks...(air cut) it needs air to to "coast" finally noticed the fan being on constantly, the air was leaking from the Horton so that it was "locked" all the time.

[twinboat]

Originally Posted by bneukam

Just got off the phone with Bendix, told them my symptoms, and they said that there should be check valves in the lines after the air dryer. If these get dirty it can cause my issues


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There should be a check valve right on the wet tank, after the dryer output line.

Next will be a T with a double check from the wet tank to the primary and secondary tanks. It may have a shuttle valve, to send air to one even if the other is ripped open.

Google " DOT Air brake 2007 " for explanations. Refer to chapter 6

[DMTTRANSPORT]

Originally Posted by twinboat

There should be a check valve right on the wet tank, after the dryer output line.

Next will be a T with a double check from the wet tank to the primary and secondary tanks. It may have a shuttle valve, to send air to one even if the other is ripped open.

Google " DOT Air brake 2007 " for explanations.

Correct, check valve mounted to the tank, not "in line"...