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Topic: Air Dryer Bypass Demo (Read 12627 times) previous topic - next topic

Re: Air Dryer Bypass Demo

Reply #40 –
Michael:  Assume Billy Jack is in service at FOT.  Tks I will look him up as I had rather pay more for the correct parts than purchase a lot of possible parts. Be there on the 11th Monday.  DAN

Re: Air Dryer Bypass Demo

Reply #41 –
@Dan Billy Jack is in parts.

see ya
ken

Re: Air Dryer Bypass Demo

Reply #42 –
Thought he was service writer?

Re: Air Dryer Bypass Demo

Reply #43 –
 Barry, are you suggesting that instead of just using a 1/2NPT coupling that maybe use a "T" instead with the centre being say 1/8"NPT and a flare fitting on that to connect the control line too??
Did I read this right?
JohnH

Re: Air Dryer Bypass Demo

Reply #44 –
Dan, as was answered by Ken, yes, Billy Jack is FOT

As the other question, he is in Parts......I shoulda put all that.

Just FYI Dan, he had to order for me but it is in their routine.  I got three sets, one for me and one for Norm and another for Tony (deengineer).  Perhas Dan you call him in advance, get him to hold a set for you or get on order (it was though a quick delivery)

By the way, the suggestion by Bret is new to me.  I am new to the RVing so not much history to have made the dryer change out every two or three years.  Need to put on my schedule for Annual Maintenance review topics.

Mike (Michael H.)

Re: Air Dryer Bypass Demo

Reply #45 –
Aside:
The elbow spec'ed by Chuck is in the NAPA computer - just wasn't availiable in Marquette
Part #2501-12-08      3/4 M-JIC / 1/2 M-NPT / 90 DEG      $5.30EA
Part #5000-08-08      1/2 F-NPT / 1/2 F-NPT / COLLAR      $2.96EA
Part#s and prices not NAPA  - From Chuck's post
The pertinent  part is "12-08" (3/4 by 1/2) for size and "JIC" for coupler type

Main:
I have studied Chucks pics of the new device and I get that part..
however... On my '96 8.3 the line coming into the rear side screws  into a big brass block which also has two smaller hoses attached.
(Pictures attached)

A year or so ago Barry talked about some device to keep oil out of (or inside) the compressor.
Something else suggested a different device was used in later years.

How does the magic pitch fork (the EDB) fit into this?

Re: Air Dryer Bypass Demo

Reply #46 –
Quote from: TheBrays –
A year or so ago Barry talked about some device to keep oil out of (or inside) the compressor.
Something else suggested a different device was used in later years.
How does the magic pitch fork (the EDB) fit into this?

Is this the thread you are referring to?
Air Dryer

Re: Air Dryer Bypass Demo

Reply #47 –
Quote from: Barry Beam –
Is this the thread you are referring to?
Air Dryer
Yes it is thanks.

So the question is, to bypass the dryer do you just connect the hoses or does the by-pass include the isolation valve?
I can almost read the referenced thread either way.

Re: Air Dryer Bypass Demo

Reply #48 –
This post has been edited to reflect new info just received from Don (Acousticart) on his experience with the bypass procedure.

Elliott,

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.

Tom Lang,

I crawled under my coach to verify the wrench size needed for the big air lines.  They take a 1 1/4" (1.25") open end wrench.  It would be nice to have 2 of this size wrench - one to hold backup on the hose (so it doesn't twist), and one to loosen the connection.  I was wrong when I recommended getting the 6-piece wrench set at Harbor Freight.  You don't really need that set, unless you're like me and just like buying tools.  (I have edited my original post)

Re: Air Dryer Bypass Demo

Reply #49 –
Quote from: cajk –
I think you may find fittings bigger than 1 5/8" on your coach

Wrong again... :-[

I crawled around under my coach looking at all the hose fittings I could find.  As I mentioned to Tom (above) the air hoses on the dryer take a 1.25" wrench.  The only other bigger connection I could find was on a couple of hydraulic hoses - that one is slightly larger than 1.5", which is the biggest wrench I had in my kit.  I'm guessing it is 1 9/16", but it might be 1 5/8".  I would say that is the biggest wrench you would ever need, at least on my 1993 model coach.

Re: Air Dryer Bypass Demo

Reply #50 –
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 –
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 –
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 –
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 –
The 37 degree is an aircraft standard.  That is an AN806 plug. 

Re: Air Dryer Bypass Demo

Reply #55 –
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 –
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== ;D 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 –
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 –
Quote from: Chuck & Jeannie –
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 –
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!