Air Dryer Bypass Demo

Topic: Air Dryer Bypass Demo (Read 9300 times) previous topic - next topic

Re: Air Dryer Bypass Demo

Reply #50 – August 08, 2014, 11:50:53 am

John, You got my comment exactly correct.

My uneducated feeling was that we were only bypassing the air dryer for emergency purposes, so why not take all the in & out hoses from air dryer and hood them together. So everything now on air dryer would still be in service, without benefit of air dryer.

I never fully understood how the compressor, unloader compressor valve, dryer, governor & wet tank work together.

I figure that governor senses hi pressure and tells compressor to open its output valve, so the compressor will free wheel, and vice versa. I thought that if we keep all parts in play while bypassing dryer, that the compressor would cycle from governor settings, preventing compressor from running all the time, building up too much pressure and preventing oil loss because the special brass side valve would still be in place.

But I have NO idea if this would work, partly because the air dryer valves probably also plays a part in controlling the total picture, and without the dryer, things may work differently.

Neal did explain that plugging the governor allows it to build air pressure to unload the compressor, I don't know if more is better when bypassing.

We have not had to bypass our dryer.

Re: Air Dryer Bypass Demo

Reply #51 – August 08, 2014, 05:54:50 pm

Today, I've been getting schooled on "Flare Fittings". I went to Home Depot yesterday to buy some small "plugs" for my EDB kit. These are the plugs for the 2 small air line hoses that connect to the dryer. One line (control line from D-2) is braided, and has a captive swivel female flare connector. The other line (from wet tank) is 3/8" black nylon, and attaches to the dryer with a compression-type fitting.

For the braided hose, I bought a brass 1/4" flare male plug, but when I got it home and compared it to the fittings on my dryer, I realized it was not correct. The brass flare connections you commonly get at Lowe's and Home Depot are called SAE 45 degree flare. The steel flare fittings on my coach are actually called JIC 37 degree flare. The two types of fittings are NOT interchangeable. If you go shopping for the plugs, be sure you are looking at the correct type of fitting. What you need is a 1/4" M-JIC Plug.
See photos below of correct steel plug, and incorrect brass plug.

For the black nylon tube, you will find the correct type brass compression fitting at Home Depot, Lowe's, etc. What you need is any type of 3/8" COMP adapter that you can close off. For instance, you could use a 3/8" COMP x 1/2" MPT (see photo below), plus a cap to seal off the pipe thread end (or 3/8" COMP x 3/8" FPT + a plug).

Re: Air Dryer Bypass Demo

Reply #52 – August 08, 2014, 06:24:38 pm

Tks Chuck for the plug info. Talked to Foretravel and their part which has 3/4 M-JIC/1/2 M-NPT/90 DEG is an odd part and was 26 dollars each. Told them it was just too expensive. On the forum they were $5.30 each. Forum is a world of facts. DAN

Re: Air Dryer Bypass Demo

Reply #53 – August 08, 2014, 07:11:16 pm

We are on the central Oregon coast and I bought there fitting at a marine supply store.
That guy says a 1/4" JIC plug will also work in a SAE fitting. But, most JIC fitting won't interchange like that.
The 1/4" JIC, his number 2408-4 cost me $0.69.
The 2403-12-12 3/4" JIC male union was $2.73.
The two JIC - NPT 90's were $5.39 each.
I'm not real happy with the 1/2" pipe coupler because it does not have flats for a wrench like Chuck showed, have to use a pipe wrench for it, but is was only $1.71.
Maybe the fitting FOT sells are DOT approved for air brake application? The marine store guy wouldn't sell them to me until I told him "heck no I won't use them for my brakes".

I don't really know if this application would be subject to DOT standards, I'm just interested in getting off the side of the highway.

Re: Air Dryer Bypass Demo

Reply #54 – August 09, 2014, 08:16:49 am

The 37 degree is an aircraft standard. That is an AN806 plug.

Re: Air Dryer Bypass Demo

Reply #55 – August 09, 2014, 08:30:35 am

Steve,

I was going to mention that yesterday, but didn't want to confuse the issue. As Steve points out, there is another possible source of 37 degree fittings. If you have ever worked around aircraft (military or civilian) you will be familiar with AN (Army Navy) fittings. After the wars, a lot of them showed up in racing cars and hot rods. They are manufactured in different colors - the color indicates the material. They can be made of aluminum alloy or steel. They are all 37 degree, and will interchange with JIC in most (non-aviation) applications. My father was a maintenance officer/pilot in the Air Force, and when he passed away I inherited cigar boxes full of the distinctive blue anodized alloy fittings. I dug through them and found some of the 1/4" plugs. These would be -4 plugs in the AN system (each "dash" number equals 1/16" of "nominal size", so -4 = 4/16" = 1/4" nominal).

Re: Air Dryer Bypass Demo

Reply #56 – August 11, 2014, 07:26:04 pm

Was in Nacogdoches today and went to A & D Hydraulics on the loop just South of MOT (2124 NW Stallings) and they had all the parts to make up the by pass including the right 1/4 inch plug. With tax about $20.30. Beverly,(there) is very knowledgeable of parts.(936-564-7760)

Mot was really==

really busy. Talked to Mike Rogers and he told me they were working very hard to please customers and are serious about customer satisfaction.

FOT was also very busy also but not a lot of coaches in the campground area. All bays were full.

Re: Air Dryer Bypass Demo

Reply #57 – August 12, 2014, 10:10:26 pm

I picked up one of these wrenches today at Harbor Freight.

It has smooth or serrated on one jaw plus plastic no-mar covers. $8 after 20% off coupon.

It goes in my emergency bypass kit.

Re: Air Dryer Bypass Demo

Reply #58 – September 06, 2017, 02:44:20 am

Quote from: Chuck & Jeannie – August 05, 2014, 05:46:58 pm

You disconnect the big air line that attaches to the isolation valve. You disconnect the big air line that attaches to the bottom of the dryer. You connect those two hoses together with the EDB. That takes the air dryer (with isolation valve still attached) completely out of service. The next step is to plug the line that runs from the D-2 governor to the dryer. The last step is to plug the black nylon air line that is attached to the Isolation Valve. That completes the bypass procedure.

Chuck, Also anyone replaced air dryer on a 2002-2004.
We are stuck in Rock Springs, WY. I am going to try to tell the short version here first. We have a new/rebuild Air dryer coming over night and hope to remove the old one install the new and continue on to our journey.
Current situation. The air dryer is bypassed by connecting the supply hose from the Engine Air compressor to egress hose. We quickly tested it and it worked (build air) I did not "remove" plug the hose that is coming from the D2 Governor to the dryer.
If i had to drive it somewhere short distance, I believe i should be able to do that, but i am just not 100% sure as to how and/if any excess air can be "purged" ? I thought I would let some air leak out of the wet tank or the tire air hose. By doing that i am aware the air compressor on the engine be running constantly. I did not think to do anything with the hose coming from the D2 Governor to the dryer. I can easily disconnected it from the Governor and screw in the extra plug that came with the new governor.
I've studied but not removed the air dryer yet, i wanted to get the new one in my hand first and have a look at it. Particularly the electrical connection. I could not unplug the electrical connection with gentle but finger firm force , so i am a bit worried about that but once i have the new one in my hand and look it over, i am hoping i can just put a flat screw driver and be able to unplug it.
I would love to be able raise the coach while doing this work but it is not a must. Today while disconnecting the lines with 1~1/4 wrench she was not raised. I had dumped all air from the tanks.

We got here Monday night from Castle Rock, CO without any issues. Tuesday morning we woke up very early at Rock Springs, WY (KOA) ready to go up to Island Lake, ID for our one week Yellow Stone vacation, but Matilda did not want to go anywhere. Both air gauges were stuck at 55 psi. First thing I replaced the governor, that did not solve the problem. I was able to find very nice local mobile diesel mechanic. With his help we were able to disconnect the lines from the dryer and connect them together bypassing the dryer. He is great and very helpful, unfortunately he has to go out of town early in the mourning so once the Overnight delivery dryer arrives at the parts store about 10-11 am I am on my own.
Thank you,
AL

Re: Air Dryer Bypass Demo

Reply #59 – September 06, 2017, 08:48:14 am

AL,

Sorry to hear of your air dryer hassles. I, of course, have not replaced (or even looked at) the dryer on the newer coaches, so no help there.

As to your question about driving a short way, here is what I would do. Fire up the coach, and see what the air system does. Watch your pressure gauges carefully. If the pressure builds to the normal compressor cut-out point and stops, then you're good to go. The compressor will probably cycle in and out just like normal. If the pressure goes past 130-140 psi and keeps climbing, then shut it down. You aren't going to blow anything up - there is a high pressure safety relief valve somewhere in your air system that should open at about 150 psi, but you would like to avoid having it release pressure. It is VERY loud when it pops open!

If the air pressure won't stop building, you'll need to do something different. A "controlled leak" like you mentioned - opening a valve to continuously vent some pressure - would work. It won't hurt anything to have your air compressor running constantly for a short while.

If you have already been able to physically reach the dryer and remove the big hoses, then you have gotten past the hardest part of doing the swap. Depending on the location of the dryer, it might take some effort to remove and replace it (i.e. some heavy lifting). Just take your time and think it through...you'll be fine.

Good luck!

Re: Air Dryer Bypass Demo

Reply #60 – September 06, 2017, 09:57:46 am

Thank you Chuck.
As you described it we did the test, pressure gauges climbed to normal compressor cut-out point and stopped.
I will know more once the part gets here and deal with it, but so far so good. The location of the dryer is not bad at all. It is in the back of the passenger side rear tire over the chassis batteries, there is access from the side and from under.

When I am reinstalling the fittings on to new dryer and to screw the hoses on to fittings do i need to use the cheap plumbers white teflon tape or should I get something better? I was at the Home Depot yesterday and noticed for few dollars more there are some newer tapes. I just don't know if i should not use any tape at all or maybe even something different like a liquid tape?

On your previous writings you mentioned about not having to drain the air bags. If i could do that it will give me some more room to work with.

Thank you,
AL

Re: Air Dryer Bypass Demo

Reply #61 – September 06, 2017, 10:09:41 am

Glad the test worked! I wasn't sure what would happen, so that is good info for all on the Forum who might face a similar situation.

It is highly recommended to avoid using any kind of teflon tape on the air system. All the smart kids on this Forum use a pipe sealing paste made for high temp air systems. I use either LOCTITE 567 PST or PERMATEX 59214, whichever I happen to find when I go shopping. You only need this stuff on the pipe thread fittings, such as the ones on the dryer. Any hose connection with a flare or compression fitting does not require the use of sealant.

Your air bags should retain pressure, even if you completely drain the pressure from your air tanks. This, of course, assumes no leaks. Do you have your safety stands with you? Ideal (safest) procedure would be to raise the coach and insert stands before working.

Re: Air Dryer Bypass Demo

Reply #62 – September 06, 2017, 10:17:00 am

A couple of things Al. The quote about the bypass demo mentions the "Isolation Valve". This device was only used up until sometime in 1999, so yours should not have it. The fittings that go on the bottom of the dryer and connect to the JIC fittings that attach the hoses are 1/2" pipe thread where they screw into the dryer. This requires some sealant and some care to tighten up tight enough to seal and still point in the right direction (if they are elbows like on ours). Don't use tape! I like Loctite 567 but that can be hard to find, and Rectorseal or similar should be fine, just be careful to keep it out of the air line.
Don

Quote from: propman – September 06, 2017, 09:57:46 am

Thank you Chuck.
As you described it we did the test, pressure gauges climbed to normal compressor cut-out point and stopped.
I will know more once the part gets here and deal with it, but so far so good. The location of the dryer is not bad at all. It is in the back of the passenger side rear tire over the chassis batteries, there is access from the side and from under.

When I am reinstalling the fittings on to new dryer and to screw the hoses on to fittings do i need to use the cheap plumbers white teflon tape or should I get something better? I was at the Home Depot yesterday and noticed for few dollars more there are some newer tapes. I just don't know if i should not use any tape at all or maybe even something different like a liquid tape?

On your previous writings you mentioned about not having to drain the air bags. If i could do that it will give me some more room to work with.

Thank you,
AL

Re: Air Dryer Bypass Demo

Reply #63 – September 06, 2017, 10:29:33 am

Don brings up a important point. Don't remove any of the fittings from the old dryer until you have the new dryer sitting right next to it! You must carefully note the direction each fitting is pointing, then remove it and transfer it directly to the new dryer. That way you'll be sure the hoses will line up properly.

Re: Air Dryer Bypass Demo

Reply #64 – September 06, 2017, 10:38:33 am

Probably obvious, but don't use any sealant on the JIC (ones with a flare) fittings, just maybe a bit of anti-size on the threads.
Don

Re: Air Dryer Bypass Demo

Reply #65 – September 06, 2017, 11:41:00 am

Quote from: Chuck & Jeannie – September 06, 2017, 10:29:33 am

Don brings up a important point. Don't remove any of the fittings from the old dryer until you have the new dryer sitting right next to it! You must carefully note the direction each fitting is pointing, then remove it and transfer it directly to the new dryer. That way you'll be sure the hoses will line up properly.

We had to remove the fittings to be able to do the bypass with a connection/joint that we had readily available. However I am aware at the direction they were pointing. I should be ok with that.

Re: Air Dryer Bypass Demo

Reply #66 – September 06, 2017, 11:42:26 am

Quote from: Don & Tys (AKA acousticart) – September 06, 2017, 10:38:33 am

Probably obvious, but don't use any sealant on the JIC (ones with a flare) fittings, just maybe a bit of anti-size on the threads.
Don

Don I found Rectorseal 5 pipe thread sealant. I am hopping it is ok to use?

__ I am worried about the electrical connection. it is very tight and i don;t know if there is a lock/latch or something.

Re: Air Dryer Bypass Demo

Reply #67 – September 06, 2017, 12:10:32 pm

If you can't get the electric plug out, try unbolting the heater element and letting it drop down. Looks like 3 bolts holding it on. Once it is loose, might be easier to see how the plug locks into place.

I see now how you accomplished the connection between the two big hoses. Very clever!

Re: Air Dryer Bypass Demo

Reply #68 – September 06, 2017, 12:16:56 pm

Al, as I recall, the heating element is hard wired to the coach via crimp terminals. It is like a resistance loop you might find if you took a coffee pot apart or maybe a charcoal starter. Just remove the purge valve cover and the screws around it and it should drop right down. You should use some thermal paste when you install it in the new one. Maybe the rebuilt ships with some...
Don

Re: Air Dryer Bypass Demo

Reply #69 – September 06, 2017, 12:24:50 pm

Should be okay, the boiling point is 330º and the data sheet says to avoid temperatures above 500º, I just like to be safe and a big tube of the 567 Loctite lasts a very long time!
Don

Quote from: propman – September 06, 2017, 11:42:26 am

Don I found Rectorseal 5 pipe thread sealant. I am hopping it is ok to use?

Re: Air Dryer Bypass Demo

Reply #70 – September 06, 2017, 12:30:15 pm

Quote from: Don & Tys (AKA acousticart) – September 06, 2017, 12:24:50 pm

Should be okay, the boiling point is 330º and the data sheet says to avoid temperatures above 500º, I just like to be safe and a big tube of the 567 Loctite lasts a very long time!
Don

Just can't find Loctite 567 in town

If i can get a way for about 1800 mil, i will redo them all when i get back home.

"You should use some thermal paste when you install it in the new one. Maybe the rebuilt ships with some..." I hope the new/rebuild unit comes with it all. I am by Home Depot and NAPA is just 4 mil.

Thermal paste like this Arctic Silver Ceramique 2 Premium High Density Thermal Compound ?

Dryer should arrive from Salt Lake City in an hour or less , I hope. Thank you! all for helping

Re: Air Dryer Bypass Demo

Reply #71 – September 06, 2017, 01:27:00 pm

Not sure about the Arctic Silver for this application... but I imagine as long as it is thick enough and has a enough volume it should work. Here is a picture of the parts that come in the Air Dryer heating kit from Haldex, as well as the most relevant part of the instruction sheet. I have a 24V new old stock military surplus air dryer with me and I bought this kit for when I get around to installing the new air dryer. You can see the heat transfer grease in the orange cup. Apparently, just "a little dab will do ya"

Don

Quote from: propman – September 06, 2017, 12:30:15 pm

Just can't find Loctite 567 in town If i can get a way for about 1800 mil, i will redo them all when i get back home.

"You should use some thermal paste when you install it in the new one. Maybe the rebuilt ships with some..." I hope the new/rebuild unit comes with it all. I am by Home Depot and NAPA is just 4 mil.

Thermal paste like this Arctic Silver Ceramique 2 Premium High Density Thermal Compound ?

Dryer should arrive from Salt Lake City in an hour or less , I hope. Thank you! all for helping

Re: Air Dryer Bypass Demo

Reply #72 – September 06, 2017, 02:29:30 pm

I was just able to remove the Air Dryer Heater and it looks just like the one you posted above it is like a ring, so the "electrical" connection i was afraid is also been tackled.
Due to smoke coming from North the Airplane landed late so I am still waiting for the dryer. In the mean time I attempted to remove the dryer. It appears very heavy and I am not so sure right now but being held in its place just with one bolt from under? It is moving around but cant get it out, yet.

Re: Air Dryer Bypass Demo

Reply #73 – September 06, 2017, 06:36:01 pm

When using air dryer bypass without governor, to keep from building too high pressure, some have opened the wet tank drain a small measured amount, and others have manually adjusted the wet tank high pressure release to a lower psi.
Also along with having an air dryer bypass joiner, having a pair of right-angle fittings already attached to the joiner in the same orientation will make installing a bypass easier. Often the right-angle fittings in use are very difficult to remove from the failed air dryer, especially on the side of the road. They are large and tight and seemingly immovable.

Re: Air Dryer Bypass Demo

Reply #74 – September 06, 2017, 08:28:29 pm

I believe that line from the governor only activates the purge valve on each cycle and does not affect the pressure of the air tanks. Correct me if I am wrong, but I have used that port to operate a spitter valve on a previous coach that didn't have any dryer filter.

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