Air Dryer Rapid cycling?

Topic: Air Dryer Rapid cycling? (Read 1628 times) previous topic - next topic

Air Dryer Rapid cycling?

August 09, 2014, 06:07:48 pm

Unable to find the rebuilt DA33100x Air Dryer and no luck on the kits lead me to a place called "Superior Industrial Friction", the only outfit I could find (thanks to Grant L for that lead!) that seemed to be be able to help me deal with the Air Dryer situation. I took ours in with the isolation valve attached (something that they had apparently never heard of before...). I sent them a PDF of the Haldex document regarding the isolation valve (or econ valve...). At first, when I called them up to ask about the progress they told me that they couldn't rebuild it but were looking for a new one for me. The next day I called and they said it was done, So I asked them about the isolation valve. What the person on the phone told me was A bit disconcerting... he said, And I quote "do you really need it?" I told him that I did indeed need it. He put me on hold for a little while to talk to the person doing the rebuilding, and he came back and told me that they had rebuilt the isolation valve. I went to pick up the air dryer and was a bit disappointed to see that they had painted the whole thing black with overspray on the apparently new desiccant cartridge. At least they had taped off the fittings to keep paint out... anyway, the people involved with the rebuild were all out to lunch so I couldn't ask them about what they had done to refurbish my unit. The cost worked out to be A bit more than a rebuilt unit would have cost in United States, though I would've been happy to pay that for a rebuilt unit if I could find one! Fast forward a day, I installed it this morning. It does function better... in other words it will build pressure and I can hear it pop off when it reaches a bit over 120 psi. What I am not sure about, is that if I just let the engine idle, the pop off valve will release every few minutes, though the pressure hasn't significantly dropped according to the dash gauges. I had never deliberately listened for the pop off while idling before this happened, So I couldn't swear that this is the same behavior we experienced before the problem happened. I would appreciate any insight as to whether or not the release of air should happen periodically under normal operating conditions without the pressure dropping to the cut in point. I have yet to do a road test because we won't be moving the coach for another a few days.
As a side note, I took off the isolation valve to have a look inside to see if anything was done other than being sprayed with black paint. I could see that the O-rings on the piston were replaced because the originals were A reddish brown and the new ones were black. One thing I wasn't sure about, was that apparently the piston and O-rings had been smeared with Vaseline or some substance like that. Myself, I wouldn't be putting something like that on a piston which should move freely. Perhaps just a little bit of light oil. In one of the threads links in my previous Post on the subject, there was reference to rapid cycling caused by A nonfunctional or missing isolation valve. So it occurs to me that perhaps the goop that they put on the piston in the isolation valve is causing it to stick.
Thoughts, ideas?
Of course, rather than posting another question on this subject, I would rather be posting on my takeaways from this experience and trying to succinctly distill the information from the various threads into one post for future thread searchers (one of which might be me!). I will attach a few pictures of the isolation valve with its parts laid out as well as an annotated picture of the air dryer and it's connections to the best of my understanding... One thing I need to add about the connections of the air dryer is that the one labled governor unloader port first goes through a "Tee" that is screwed into the port labeled control on the other side of the air dryer. The hose from the other side of the tea goes up to one of the governor unloader ports.
Thanks, Don

Re: Air Dryer Rapid cycling?

Reply #1 – August 09, 2014, 06:13:36 pm

Quote from: acousticart – August 09, 2014, 06:07:48 pm

in other words it will build pressure and I can hear it pop off when it reaches a bit over 120 psi. What I am not sure about, is that if I just let the engine idle, the pop off valve Will release every few minutes, so the pressure hasn't significantly dropped according to the Dash gauges.

Don,

Do you know what the D2 Governor is set for as far as cut in/out pressures? Is it possible you just need to adjust the setpoints on the governor?

Re: Air Dryer Rapid cycling?

Reply #2 – August 09, 2014, 06:22:28 pm

You can adjust the set point for compressor cut in/cut out, but you cannot adjust the differential between the two - it is fixed at about 20 psi. So if Don's governor is unloading the compressor at 120-125 psig, then it should not "load" the compressor again until the pressure in his wet tank has dropped to approximately 100-105 psig. Unless there is a significant leak somewhere, it should certainly take more than a "few minutes" for this to occur.

Sounds like something is not right to me. Hmmm...

Re: Air Dryer Rapid cycling?

Reply #3 – August 09, 2014, 06:38:17 pm

The "O" rings for the isolation valve should be the dark red high temperature rings.
I'm worried about the quality of your dryer overhaul.

Re: Air Dryer Rapid cycling?

Reply #4 – August 09, 2014, 06:56:25 pm

You and me both John! I'm never one to be that trusting when it comes to having people who are supposed to be professionals work on my equipment. Too often, I have ended up redoing the work and sometimes extra work calls by the work that was done. The situation is somewhat better than before, because at least I don't have moisture accumulating in the tank. However, I really don't want to have the compressor wear out prematurely because it's constantly cycling. Naturally, the place that did the rebuild is closed for the weekend. However, I will be contacting them on Monday... not that I have high hopes for a satisfactory resolution. I imagine that I will hear them tell me that it's probably a problem somewhere else in the system such as a compressor unloader valve. And of course, it could be something else altogether... maybe the work they did was fine. I can only hope at this point...

Don

Quote from: John Duld – August 09, 2014, 06:38:17 pm

The "O" rings for the isolation valve should be the dark red high temperature rings.
I'm worried about the quality of your dryer overhaul.

Re: Air Dryer Rapid cycling?

Reply #5 – August 09, 2014, 07:15:12 pm

There is a guy here on the forum that goes by "the o ring guy".
Think he is in Austin, Tx.
He had to buy about 100 of each of those red o rings.
If you send him a stamped self addressed envelope he may still send you some.
He did that for me a few years ago.
Then you can rebuild the isolation valve your self. The black o rings will probably last for awhile.
You might go back to your old air governor to see if the cycling stops.
Always something but you will get to the finish line eventually!

Re: Air Dryer Rapid cycling?

Reply #6 – August 09, 2014, 09:55:12 pm

I was going to stick up A spare bendix D2 governor anyway, So I guess I'll do that put it on and try it. You're doesn't even go down to PSI before the pop off valve releases. About Half a minute before that happens, I hear a little bit of a sucking sound which lasts just a few seconds... at this point I haven't located its source. I suspect it may be from the dryer, though not the purge valve. I may take the isolation valve apart again and clean all the goop off of it to see if that makes a difference.
Don

Re: Air Dryer Rapid cycling?

Reply #7 – August 09, 2014, 10:00:44 pm

Don,

I've been reading a bunch of posts about "Rapid Cycling" of air dryers. Google that term, if you have not already done so, to see those posts on other forums. Some of the dryer setups may be different, but the principle is the same. Apparently this is a fairly common problem.

The majority of solutions involve finding a hidden leak in the part of the system that includes the governor, the unloader valve on the compressor, the hoses between the governor and the dryer and the compressor, and the purge valve on the dryer. The isolation valve is probably in this group, also.

Do you have a air gauge on your wet tank? If not, can you add one? You could attach it to the end of the drain line, or there is a unused 1/8" tapped hole in the bottom of the D-2 governor (has a plug in it) which will read wet tank pressure. You said your dash air gauges do not show a pressure drop. That means the problem is "upstream" of the wet tank, and the one-way valves are preserving pressure in your other tanks. If you put a gauge on the wet tank, and it does not show a pressure drop, then the problem is confined to the items mentioned above.

Re: Air Dryer Rapid cycling?

Reply #8 – August 09, 2014, 10:25:13 pm

Don,
Did they use new parts to rebuild it or just replace the o-rings and such. If they reused the turbo saver valve it might be the problem. Mine had a cracked seat causing it to cycle often because air was leaking past the o ring. That's my thought anyway. These dryers are very simple devices and if they put in new parts correctly it should be something else. Maybe your isolation valve could have something to do with it. Hope you get it figured out,

Mark

Re: Air Dryer Rapid cycling?

Reply #9 – August 10, 2014, 01:50:10 am

The problem is new since the dryer rebuild, so I doubt that is the compressor unloader. The other items are definitely possibles as is Maz's suggestion of the turbo saver valve. My money is on the isolation valve, but it could easily be one of the other dryer components. I will try changing the governor to see if the behavior is the same, just because it is much easier than wrestling with the isolation valve and its fittings. It is disappointing to still be grappling with this problem when this should be a vacation, but such is life. I appreciate the input and I guess there will be several positives as a result of all this. Not the least of which is more tools in my knowledge tool box...

No air gage on the wet tank, but adding one to the extra port on the governor and remote mounting it where it is easy to see sounds like a worthwhile project. Thanks for the suggestion...
Don

Quote from: cajk – August 09, 2014, 10:00:44 pm

Don,

I've been reading a bunch of posts about "Rapid Cycling" of air dryers. Google that term, if you have not already done so, to see those posts on other forums. Some of the dryer setups may be different, but the principle is the same. Apparently this is a fairly common problem.

The majority of solutions involve finding a hidden leak in the part of the system that includes the governor, the unloader valve on the compressor, the hoses between the governor and the dryer and the compressor, and the purge valve on the dryer. The isolation valve is probably in this group, also.

Do you have a air gauge on your wet tank? If not, can you add one? You could attach it to the end of the drain line, or there is a unused 1/8" tapped hole in the bottom of the D-2 governor (has a plug in it) which will read wet tank pressure. You said your dash air gauges do not show a pressure drop. That means the problem is "upstream" of the wet tank, and the one-way valves are preserving pressure in your other tanks. If you put a gauge on the wet tank, and it does not show a pressure drop, then the problem is confined to the items mentioned above.

Re: Air Dryer Rapid cycling?

Reply #10 – August 10, 2014, 07:41:15 am

Don,

I have to agree with the others concerning the black o-rings. I have had, in industrial situations, where the lower temp o-rings were mistakenly placed in a rebuild. They didn't last much longer than it took to reinstall the equipment. Factory did the rebuild, got to pay to remove, repair and replace it again.

Sorry the vacation part isn't going as planned, but with your analytical mind and the help from a few dozen forum friends I'm sure the answer is a short distance away.

Keep us informed.

Larry

Re: Air Dryer Rapid cycling?

Reply #11 – August 10, 2014, 09:33:15 am

Don,

Here is my "poor boy" air pressure gauge installation. It is mounted with the fuel pressure gauge from my previous Fuel System Science Project. (Fuel System Science Project)
I used brass fittings, poly tubing protected with split wire loom, and a gauge - all purchased at Home Depot. Inexpensive, but functional. Of course, I am sure you will machine your gauge mount out of solid billet aluminum!

Re: Air Dryer Rapid cycling?

Reply #12 – August 10, 2014, 10:44:05 am

Don,
Think maybe you might like to see this attachment concerning your air brake system, maybe it will have the clue your needing.
Good luck
Dave M

Re: Air Dryer Rapid cycling?

Reply #13 – August 10, 2014, 11:22:50 am

Don,
Is it the purge valve or the safety valve that cycles?

Re: Air Dryer Rapid cycling?

Reply #14 – August 10, 2014, 06:55:35 pm

I had a similar problem. It turned out to be a check valve inside the dryer. The rebuild kit I purchased had one included. I don't have the model number of my dryer but I definitely had the same symptoms. Mine would purge every 4 to 5 minutes.

Re: Air Dryer Rapid cycling?

Reply #15 – August 10, 2014, 07:12:54 pm

Thanks for the pics Chuck. John, I believe that it is the purge valve that is releasing periodically, with some unknown component making a sucking sound about thirty seconds before. I took the day off today to do tourist things but will probably be getting back to it tomorrow morning before I call the place that rebuilt it. I am parked in a drive way that is just long enough to get the coach out of the through way of an alley. So close to a garage, that I need to pull it forward about a foot to open the engine hatch and then I back it back up to keep the alley clear. At the end of the session, I have to reverse the process... so I can't as easily give in to the impulse to go check this or that possibility as I would like to. Thanks for the troubleshooting guide Dave. There are some useful tips if I need to test the compressor unloader valve or other component, but since all was well before the dryer went south, I am focusing on that as the probable cause for now. All a chance to learn more about these vital systems... but I will be glad to forget about it for awhile when I finally get it sorted out.
Check valve at the output was replaced, but it is possible that something is stuck on the seat creating an internal leak...
Don

Re: Air Dryer Rapid cycling?

Reply #16 – August 10, 2014, 09:41:42 pm

Don,
You may have seen this already but I am posting it just in case you didnt. You can see in the picture where the valve is I had problems with.

Mark

Re: Air Dryer Rapid cycling?

Reply #17 – August 10, 2014, 10:39:43 pm

Thanks Maz! I don't believe that I saw this particular one (Hard to be sure, I have read a lot about this in the last week!). There are some easy to do and good functional checks in there...
Don

Quote from: MAZ – August 10, 2014, 09:41:42 pm

Don,
You may have seen this already but I am posting it just in case you didnt. You can see in the picture where the valve is I had problems with.

Mark

Re: Air Dryer Rapid cycling?

Reply #18 – August 10, 2014, 10:56:42 pm

Quote from: acousticart – August 10, 2014, 10:39:43 pm

.................I don't believe that I saw this particular one........................

Don
Air won't build past 40psi, stuck by roadside
Neal

Re: Air Dryer Rapid cycling?

Reply #19 – August 10, 2014, 11:16:28 pm

Touché Neal! Like I said, I have looked at so many documents on this subject this past week that I have a hard time keeping them straight

One factor is that as I started this process, the terminology and nomenclature were relatively new to me so as I look over the same information today, new things jump out at me! I do appreciate all the helpful info I have received over the course of this ordeal (which is nothing compared to my bulkhead adventures!) and I have tried to filter what seems relevant to my situation as I go along, because I simply can't take it in all at once. Over the course of time, I seem to start getting a handle on things and it all looks different to me. Don't know if I am there yet with this one, but getting closer all the time...
Don

Quote from: Neal Pillsbury – August 10, 2014, 10:56:42 pm

Don
Air won't build past 40psi, stuck by roadside
Neal

Re: Air Dryer Rapid cycling?

Reply #20 – August 11, 2014, 12:03:21 am

Don,
Sorry you're having this go of it!
Air systems (like electronics) can be very frustrating because if components PARTIALLY fail (more often the case than not), they don't present symptoms that one would normally predict.
You are already well versed, but if your offense maneuvers aren't panning out, the best defense is to try to accurately describe the symptoms, in as much detail as possible, and maybe one of us has either seen the exact issue before, or can be of intellectual help. Your description, thus far, leads to many possibilities between the governor and the wet tank, including the compressor unloader (though not likely, based on chronology).
I'm no expert, but I do wish that I were there to help.
Neal

Re: Air Dryer Rapid cycling?

Reply #21 – August 11, 2014, 03:20:23 pm

Here is the current problem, as accurately as I can describe it;
First a recap/summary for those reading this thread not familiar with the relevant threads leading up to this, those currently abreast of this thread and its predecessor feel free to skip ahead

:

Begin Recap: While driving on the way to Calgary from the US Canadian border, the dash warning lights and alarm sound came on; first the level system lights, and then as I noticed the air pressure dropping, the low air pressure light. I was able to find a wide spot in the road before the parking brake engaged itself. Once pulled over, the air pressure would not build over 40PSI and the parking brake would not disengage. Air was spilling out the purge valve continuously as the engine was running. I had a new Bendix D2 governor with me so I installed this as it was the easiest option to try. No change in the symptoms. With the helpful suggestions on Foreforum, I was able to cobble together a bypass using the two ¾" JIC by ½" MPT fittings and a ½" fpt gate valve I had in misc plumbing parts. The bypass also required plugging the unloader port at the governor (⅛"pipe thread plug from the old governor) and the ¼" plastic brake line that runs to the wet tank from the isolation valve at the passenger side of the dryer (for this I had a cap plug made up from the step cover regulator and drop down step... it uses a brass compression fitting and can be found at Home Depot etc.). The bypass enabled us to proceed to Calgary and required frequent tank draining because of water build up.
End Recap summary, now to the current problem: Rapid Cycling of Air Dryer Purge

Since rebuilt air dryer was installed (our old one was rebuilt by a place called "Superior Industrial Friction" because we were unable to locate either Haldex rebuilt kits or a factory rebuilt unit in Canada; we tried in Calgary, Red Deer, & Edmonton), the pressure builds normally and at approx. 125PSI indicated on the dash gauges, the Purge valve releases air as per normal. there doesn't appear to be any oily residue from this discharge as I can place my hand below and feel the air escaping and there is nothing to wipe off after the purge. Approx. 3 to 4 minutes after the purge cycle completes I hear something that sounds like a vacuum sucking sound for just a few seconds and 30-45 seconds later it purges again. All without a noticeable drop in indicated air pressure on the dash gauge. I haven't been able to find where the secondary sucking sound comes from though I have been laying under the coach while it happens. It may be air escaping, rather than a vacuum, but I haven't been able to feel it. It sounds like it might be coming form the pressure relief valve, which appears to be new with the Air Dryer rebuild (it has what looks like the a foam rubber filter sleeve around it which was missing if ever present on the old one). It is difficult to test extensively because I am trying to minimize the smell of diesel for the benefit of our host's neighbors and to recreate the sound just once requires about 5 minutes of idling.
That is all I can think of at the moment... would welcome any follow up questions that will help me narrow it down without running tests on every possible system (as that would require a lot of running the engine).

Thanks, Don

Re: Air Dryer Rapid cycling?

Reply #22 – August 11, 2014, 03:22:37 pm

I have a Detroit doing the same thing as we speak.. my mechanic promises it is the d2 governor.. I just had 2 delivered and he is putting 1 on now... cycles about every minute..

Re: Air Dryer Rapid cycling?

Reply #23 – August 11, 2014, 03:50:20 pm

Quote from: acousticart – August 11, 2014, 03:20:23 pm

Approx. 3 to 4 minutes after the purge cycle completes I hear something that sounds like a vacuum sucking sound for just a few seconds and 30-45 seconds later it purges again. All without a noticeable drop in indicated air pressure on the dash gauge. I haven't been able to find where the secondary sucking sound comes from though I have been laying under the coach while it happens. It may be air escaping, rather than a vacuum, but I haven't been able to feel it.

Don,

The isolation valve that has the new o-rings, is it the internal valve mentioned in the posts linked below by Pamela and Mike?

Remanufactured Haldex Air Dryer
Haldex air dryer isolation valve

Re: Air Dryer Rapid cycling?

Reply #24 – August 11, 2014, 04:03:25 pm

Michelle,
It is the one mentioned in the links you posted, though it is not internal to the Air Dryer on the DA33100- but rather screwed into the Air Dryer input ½" pipe thread port. Here is a repost of the picture of it taken apart with labels; Note there is another fitting not shown in the picture that has the ½" male pipe threads on the side that goes into the dryer and male threads that are not tapered on the other with a 1 ¼" Hex in the middle sealed to the isolation valve (really a part of the valve) with an 'O' ring.
Don

Quote from: Michelle – August 11, 2014, 03:50:20 pm

Don,

The isolation valve that has the new o-rings, is it the internal valve mentioned in the posts linked below by Pamela and Mike?

Remanufactured Haldex Air Dryer
Haldex air dryer isolation valve

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