NOTE: If you are unfamiliar with the air dryer bypass tool, see this topic: Air won't build past 40psi, stuck by roadside (http://www.foreforums.com/index.php?topic=21975.0)
Don and Tys (acousticart) recent roadside experience with a malfunctioning air dryer was a wakeup call for me. I decided I would go through my air system and replace or repair any questionable components, and in the process familiarize myself with the procedure required to use the Emergency Dryer Bypass (hereafter referred to as the EDB). Those of you who have never had a dryer go bad may assume that using the EDB is pretty simple - you just remove the air lines from dryer and connect them. Well, after simulating a "dryer failure" in my driveway (with safety stands in place) and attempting to use my EDB, I can tell you that it may not be quite that easy. In fact, for me it was VERY difficult! My sincere congratulations to Don for being able to accomplish this task under less-than-ideal conditions!
Your first problem will be access. I know different model coaches have the dryer mounted in different places - yours may be easier to reach than mine. Dryer failure usually means no air pressure, which means no lifting the coach to install safety stands. My AD-9 air dryer is mounted high up in the driver side rear corner of the engine compartment, hidden behind one of the hydraulic tanks. Reaching in through my engine cover, I can only touch it with one hand. Crawling under the coach is the only realistic way to work on it, but with the coach sitting down on the mechanical stops, you will have very little room to maneuver.
Your second problem is tools, or rather lack of them. I carry a pretty good selection of tools in my coach, but I only had one wrench that was big enough to remove the big air line connections: a 12" (300mm) Cresent wrench. A adjustable wrench is not ideal when faced with VERY tight connections, but it will work. Personally, I plan to buy several properly sized open end wrenches, so in the future I will be better prepared. A couple 1 1/4" heavy duty spanners should do the trick. A 2' "cheater pipe" would also be very helpful!
You will need some way to plug the small "control" air line that runs from the D-2 air governor to the air dryer. It will probably be either a 1/4" or a 3/16" flare connection - I would carry both size plugs (or a selection of sizes) just to be safe. See the photo of the required flare plug (below).
There has been some discussion recently about the "shape" of the EDB. Some say a simple 1-piece double union connector would work. In my case, it would not. There is no way I could bend the big air hoses enough to make a straight connection. Only a "U" shaped bypass would work for me.
On to the demo! The photos below (hopefully in order) will show the following:
1. AD-9 air dryer viewed from the engine hatch. The small braided "control" hose just visible to the left of dryer is the one you need to remove and plug.
2. Close up of small braided "control" hose. The flare plug goes here.
3. Photo of type of flare plug that is required.
4. AD-9 air dryer viewed from under the coach. The 2 big braided hoses (one in foreground, one in background) are the ones to remove and connect together.
5. Big hoses detached from dryer and connected with EDB.
6. Better view of "control" hose connection. There is a "T" double flare connection at the base of dryer (below the white label). Control hose connects to the "T".
GREAT POST CHUCK !!!
Chuck, thank you ^.^d
How often could this happen?
If its more than every 3-4 years; would it be possible to install a perminate bypass?
Nice Job Chuck! ^.^d
Don
Chuck,
Great follow-up!
On your coach, is the D-2 Governor easily accessible? It doesn't matter which end of the pneumatic Governor "control" signal is plugged, as long as the Governor air escape is terminated. On my coach, the Governor is very accessible. Removing the flexible tubing (headed toward the Haldex Pure Air Plus Dryer) and using an 1/8" NPT plug in the Governor "control" port is the easiest way.
Thanks. Very nice.
Neal
Now your turn Neal to beat me to it on posting about removing the D2 line and plugging.
I bought Friday the fittings to make a bypass etc "just in case" even though I regularily service the Dryer (every 18 months) and hope never to need to use the "rescue kit" !!
Luckily the location of Dryer on our coach is very accessable on the rear crossbeam that contains the hitch, although you still have to get under this tube to undo lines.
Good posting Chuck.
JohnH
Very informative and helpful post, including the need for proper tools.
Thanks,
Rodger
On my coach, it would be a toss up. The D-2 is hidden behind the
other hydraulic reservoir, on the passenger side of the engine compartment. It would be equally easy (or difficult) to disconnect the hose and install the appropriate plug at either end of the "control" hose. Might depend on what kind of plugs you have available, male NPT or male flare. I will be adding a selection of both type plugs to my tool kit!
Almost anything is possible! Would it be worth the effort? Only you can answer that. You would need 2 valves, one at inlet and one at output, on the dryer. Then between both big hoses and the valves, you would install "T" connectors. A cross pipe (or hose) with another valve in the middle would connect the 2 "T"s. All these fittings would have to be fairly large gauge, to match the size of the air hoses. Finally, you would install a small valve somewhere in the "control" line.
Normal operation: The "control" line valve open, the valve between the "T"s closed, and the dryer inlet and output valves open.
Emergency operation: The "control" line valve closed, valve between the "T's open, dryer inlet and output valves closed.
Give it a try, and let us know how it works!
Chuck, how often is the possibility a EDB would be needed?
One of those questions that is impossible to answer - maintain your air dryer as recommended (by the manufacturer, and on this forum) and you
may never need one.
Thats what i thought, but there are "gear heads" here like Don. If it happens to him and since i dont have his "roadside" skill set it, this is a good option that I need to consider.
I am at best an amature, my Dad is expert but 85 so looks like a hundred or so in the drive will probally net save $300-500 plus a tow, time, frustration etc, etc :o
Thanks Chuck! ^.^d
Wow, nice write up.
Larry
Howdy Chuck,
Great write-up!! I bought the fittings to make an EDB, and I'll be getting a set of the large wrenches. Thanks for the link to HF.
Thanks for all your great work on this issue. Dave A
Thank you!!!
I'm especially glad to learn about that small control line from the D2. I was confused about it until now.
Just a question about the large wrenches... a few days ago Roger Berke of Aquahot posted a HF link for some as well (15 Piece SAE Service Wrench Set (http://www.harborfreight.com/15-piece-sae-service-wrench-set-93667.html)). You mentioned a 2' cheater pipe, so I'm wondering if the pipe would be easier to use on this other set. Just curious about your opinion on which set. The price is the same; Roger's set only goes up to 1 5/8" though. Would that be big enough?
sure appreciate your photos!
Thanks, Dick
Went to Home Depot and Lowes and could not find the parts to make the EDB. Will be in Nacogdoches on the 11th of this month so will go by the hydraulic shop on the loop and see if they have the parts. Can you give me again the list and size of the parts. They have been mentioned here in so many sizes I am now confused. Are there more than one size air dryer? DAN
For me, when I serviced my first air dryer and didn't have wrenches big enough to do the job, instead of buying a set of large wrenches and most likely using only one or two of them, I bought a Hex wrench from Ridgid Tools. It's about 10 1/2 inches when fully opened, jaw size is from 1 1/8 to 2 1/2 inches. You don't have any hose fittings larger than that on our coaches. You will have to use a "cheater" pipe with it for the big fittings.
I carry three(3) different size PVC pipes, about 18" long
They are labeled " Cheaters, do not remove "
Easy to cut off if they are to long to use, replace when you get home.
Save the old one too.
We used to use those in the oil field - it's a good tool (as is everything from Ridgid). We would put too big a cheater on them, and bend the handle. Ridgid would replace with a new one, no questions asked. Only concern I would have is the size of the wrench versus the working space available. I think you might run into situations where this adjustable wrench would not fit, but a standard open end would. Best idea would be to have both! Remember the old saying: "He who dies with the most tools, wins!".
Bill, now I know what to do with the scrap pvc! Thanks, always used conduit, this is lighter ^.^d
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
I think you may find fittings bigger than 1 5/8" on your coach - only way to be sure is to crawl under there and look. As for the cheater pipe, it must be just big enough to fit over the "non-working" end of the wrench, but not too big or it will slip off and you'll hurt yourself. Buy the wrench set, then scrounge up the cheater pipe that fits.
Someone who is an expert, please correct me if I got this wrong...
My understanding is that you should never use Teflon tape on other than water pick especially, as a Teflon fragment getting away can cause a world of grief.
Thai being true (?), what, if anything, should be used to seal the threads?
Thanks, I'll go for the larger sizes. ;)
Does anyone have the part number for the control line flare plug?
I'm trying to get the pieces together, but without access to my coach for a couple of weeks.
Just what are the wrench sizes needed for the two large hoses?
If I remember correctly (it was five days ago after all ::) ), 1 ⅛" on our coach. If you need to take the connecting block off on the input side (which has the line going to the wet tank and the line going to the governor as well as the hose, that was 1 ¼".
Tom, only use pipe tape or pipe dope on NPT ( national pipe thread) If you use the tape, leave the first two to three threads bare. That would go for the dope also. JIC fittings are self sealing
Richard B
Tom,
I will be back under my coach tomorrow morning. I'll take some measurements of the various hose end fittings and get back to you on the wrench sizes. As for the flare plug, it would be good to have several different sizes: perhaps 1/4", 3/8", and 1/2". Never know when you might want to plug off a air line somewhere on your coach.
Chuck, would be nice to have ALL the wrenches a person might use, but hate buying a set of 15 or so just to use one or two. With the hex wrench having a very narrow head, and you having used them, you know how they can get into some very tight places.
Richard B
That is what I figured. I was hoping you would chime in on this.
I also figured leaving the threads bare would be plenty good enough for this purpose.
(and I thought NPT was New Process Technology, oh well)
Thanks, Tom
Actually, Plan "A" is to service or replace with factory reman the dryer every two to three years. Will substantially reduce the likelihood of dryer failure.
Plan "B" is a good fall-back position, but Plan "A" is preferred.
Brett, + one on that!
I'm in, with both plan A and plan B.
I had my air dryer completely rebuilt six months ago, and just bought the parts for the bypass kit on eBay.
Not an expert, but this is what I use for air lines...
50ml Tube Loctite[REG] 567 PST High Temperature Thread Sealant | Fastenal (http://www.fastenal.com/web/products/details/0150214)
Don
If you buy the "really big wrenches"™ from Harbor Freight you can use the one of the other wrenches as a cheater bar. If you can get the box end of the wrench on you can wedge the box end of another wrench on the open end of the wrench. If you can only get the open end of the wrench on you can use the box end of another bigger wrench over the box end. I've only had one bolt I couldn't get off using this method and that one came off with the addition of PB Blaster and some heat.
Hope that makes sense!
see ya
ken
Isn't it possible to keep the D2 governor in the system with the air dryer bypass? Maybe have a small hose fitting on the bypass so the governor stays, to open the compressor output when max or to restart compressing when min psi is sensed.
Our air dryer has a brass valve fitting on one port that has several hoses. I think it is needed to keep from pulling oil from compressor. This valve would need to be part of the bypass to protect the compressor.
Barry,
D2 Governor has 3 unloader ports.
1 for air dryer
1 for compressor intake valves unloader
1 not used (at least the way mine is plumbed)
Stopping the control signal air leaking to the air dryer (after "control" flexible tubing has been removed) is necessary in order for the governor piston to fully complete its travel. That will allow the control signal outlet pressure to build and send the high pressure control signal to the engine compressor intake valves unloader. That unloads the compressor allowing bypass flow until the governor low press setpoint (wet tank pressure) is reached and the cycle starts over again.
Neal
Dan, you can get the parts from Billy Jack, I did about two months ago when this topic began. I guess cheaper elsewhere but getting direct from FOT I though I would get the right fittings. So is you heading to Nac soon, that one option
mike
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
@Dan Billy Jack is in parts.
see ya
ken
Thought he was service writer?
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
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.)
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?
Is this the thread you are referring to?
Air Dryer (http://www.foreforums.com/index.php?topic=14651.msg86110#msg86110)
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.
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)
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.
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.
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).
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
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.
The 37 degree is an aircraft standard. That is an AN806 plug.
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).
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.
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.
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
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!
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
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.
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
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.
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
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.
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.
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!
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
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 (https://www.walmart.com/ip/Arctic-Silver-Ceramique-2-Premium-High-Density-Thermal-Compound/20449154?wmlspartner=wlpa&adid=22222222227014945972&wl0=&wl1=g&wl2=c&wl3=40880206832&wl4=pla-78810709472&wl5=9028770&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=20449154&wl13=&veh=sem) ?
Dryer should arrive from Salt Lake City in an hour or less , I hope. Thank you! all for helping
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" ^.^d
Don
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.
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.
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.
We are all fixed up and hope to leave first thing in the morning. Thank you all for your help. Once again Foretravel friends are priceless, you almost make braking down fun :)
Going forward like a oil/filter change just get a rebuild Air Dryer once a year? I understand the bypass valve and all that to use when it stops working unexpectedly but what is the common practice should be? Mine was rebuild by FT 17 months ago and since than we only had about 3-4000 miles.
Those elbow fittings are not practical & I plan on getting straight ones, anyway.
I think every two years would be plenty adequate as far as getting "remanufactured" air dryer. Definitions of "rebuilding" varies too much depending on who does it. As to the elbows, our air lines wouldn't meet up with the fittings on the air dryer without the elbows, your must be a bit different.
Don
I sure hope can go for 2 years. If it wasn't for the steep core charge i would almost starting to have a spare after 12 months.
Yes for ours straight fittings will work just fine, I wonder why they did not do it like that to start with, who knows.
Actually, I am comfortable with every three years. But, I really like the factory (i.e. the factory that made them) re-man, as all valves, heater and filters are new.
I am happy to just install the Haldex service kit every 18 months per the FT service schedule.
I replaced ours last year with a spin-on with heater/etc. It was the OEM with 100,000 miles but seemed to be working fine. Just figured it was time. The spin-on changes in a couple of minutes.
Pierce
Which brand, SP?
Thank you,
AL
I called Bendix today and talked to a Tech Person and asked how often my AD9 Dryer needed servicing. His answer was all applications are different. But he said when you change one keep track of how long until you start seeing an accumulation of water discharge from wet tank when you drain it. Then back it up a month and change at that interval. I asked about a suitable replacement with a spin on filter and he recommended one But it has the air governor built into it and I would not use the Governor on the compressor D2. I don't think I want to change D2 are cheap and easy to replace when needed. Having governor built into dryer to me might not be as easy to service.They always crap out at the worst time and place. I have been getting water out of my wet tank every couple weeks but the only compressor running is the 110 volt that occasionally comes on to refill air bags. Does that air go through wet tank? I guess I need to pull out coach books when I get back off the road.
Think most of the aftermarkets are made in Poland by the same company. Germany is the original. I purchased ours from National Drivetrain for about $90-100 delivered. Quality looks excellent. Make sure to loosen and then tighten the spin-on once you have it installed as they are really stiff. I did need to buy a couple of inexpensive fittings. Make sure the hydraulic hoses do not touch each other after installation or they will fray and fail. AIR DRYER ASSEMBLY - REPLACES MERITOR WABCO SYSTEM SAVER 1200 SERIES R955205... (http://www.ebay.com/itm/AIR-DRYER-ASSEMBLY-REPLACES-MERITOR-WABCO-SYSTEM-SAVER-1200-SERIES-R955205-/252085515947?hash=item3ab177b6ab)
I modified the old bracket and then did a really quick powercoat on it. Buy a crow's foot before starting. Here is the link to the Google album showing the installation and crow's foot. Wabco-Meritor 1200 Air Dryer U300 Installation - Google Photos (https://goo.gl/photos/AJjNf1EETFq5aLzDA)
For owners with problems on the OEM dryer, make sure the power to the heating element is hot (12V).
Pierce
Thanks Pierce,
Changed out my D 2 today as it took a lot longer than normal for pressure to build. Thought all was good , came home tonight, fired it up to build enough air to get the jacks under it and it still took way too long.
Once up it holds air for a few hours with no signs of leaks.
Does this sound like the dryer control line is suspect?
I got a remanufactured AD9 for $155 with a $90 core charge, so only $65 to replace the whole setup. D2 was $15ish.
To figure it out, we need to find out where the pressure goes down to and how long it takes to get there after you shut down. If it's in the cycle range, it should build from 80 psi to 100-110 psi in a minute or so. If it's below, it could be an airbag leak or possibly related to the dryer. As I remember, once ours goes below 80 psi, it seems to take forever to come up. The tanks and bags take a lot of CFMs to get to the 80 psi mark.
First, I like to listen for leaks, then I bring out the small Hudson sprayer with soap or better yet, go to your local party store and get 8 oz of Pustefix. Bubbles don't pop and last a long time. Any leak anywhere will show up. Amazon.com: Pustefix Premium Bubbles Refill 8.3 fl.0z.: Toys & Games (https://www.amazon.com/Pustefix-Premium-Bubbles-Refill-fl-0z/dp/B0002HYC00)
OK, driving down the road, how often does your compressor cycle?
Pierce
The slow pressure build is new . Last time out , 3 wks ago, pressure built in a few minutes at low idle to 100. The build was linear all the way up. Today it builds to 50 right away and then sits @ about 70 for few minutes.
I listen well for leaks , found a small one at the dash vacuum motor that was not in use. Plugged it off. The park handle has a very slight hiss some times but always has had it. No loss when pushed in. I sprayed the bags/ look old but sound and test tight.
This morning ( getting to move the bus to high ground) air would not go to 80. New D2 built to 50 in a minute but took 5 min to get to 80 and then went quickly to 125 and stayed 125 . Shut down air stayed about 100 for 5- 10 min and still showed 60 or more on the red needle and 70 on the green needle after 6 hrs.
I don't know if your air compressor is anything similar to the Bendix one on my crane, but I had unloader valves sticking causing a similar problem.
Besides the unloader valve, you might take a look at the compressor head. Jerry Maddux recently overhauled his and is the expert here.
Pierce
Or a sticking purge valve on the dryer, it's before the check valves so once tank pressures are up they tend to stay up and it don't show up in a leak down test, same goes for any lines before the check valves.
The unloader and purge valves are my suspects as I read more about how it works. Pretty sure the compressor is good as it
recovers,builds quickly from multiple brake use. right back up to 120.
Is there a way to block the purge valve to check the rest? Taptap test?.
BTW, Thanks for the tips regarding the spare D2 in the bus , I would have been beached without it for sure . This forum has been a life/wallet saver..:)
Might be able to put some foil duct tape over the purge port and see if that helps to identify a leak
Bendix manuals here;Equipment Bendix Commercial Vehicle Systems User Manuals - Read online or... (http://www.manualsdir.com/brands/bendix-commercial-vehicle-systems/193.html)
It looks like the early Cart uses a Tuflo 501, belt drive .
The unloader valve is inverted under the head. Drain coolant to compressor level , remove head etc.
I freed my unloader by spraying Corrosion X in the port from the governor. Hasn't stuck again going on 6 mo.
Will try that . Thanks,MM
Seems to help. Has built air 4 times solid .
What happens when an air dryer fails...........does it become blocked that air won't pass through it?
If that's the case then why not incorporate a shut-off valve linking the two air lines (like an H pipe exhaust) anywhere before the dryer? Then in the event of failure you should only have to just open the valve, and not get dirty.
Worse, way worse
Desiccant is like fine talc and contaminants the valves in the HWH system.
Major $$$ and PITA
System doesn't stop working, but components do
1. Search "air dryer failure" on this Forum. You'll be treated to all the gory details!
2. This has been discussed. See Reply #3 and Reply #9 in this thread.
I understand..................thanks guys.
Your 'bypass before failure' idea could work if you add two ball valves in your H to close off air to and from dryer before opening your bypass ball valve.
Would result in wet air in system, not a good thing??
I thought the intent of this thread was to enable someone to move their coach by simply by-passing the dryer?
That's good news Mike. Hope it works. To replace the unloaders on a Bendix.Tu-Flo 501 mounted on the back of a DD6V92 you have to remove the compressor head if they are frozen and it's a royal PITA. You can test the operation and for leaks of the unloaders by using a small shop air compressor with about 100 psi with a line and fitting to the unloader port and removing the air supply hose from the turbo. BENDIX TU-FLO 501 AIR COMPRESSOR Manual (Page 27 of 36) (https://www.manualslib.com/manual/392715/Bendix-Tu-Flo-501-Air-Compressor.html?page=27#manual)
Jerry
T-Man,
You are correct - that was the original intent of this thread. It has been wandering around a bit, topic-wise, and members sometimes lose track of what was initially being discussed.
A custom, built-in manifold that would allow
temporary bypassing of a
broken air dryer would certainly be feasable. The question is would it be worth the trouble to install? If the air dryer is maintained properly, a owner may
never have a problem that would require bypassing. But if you want to try building one, I say go for it! Do a photo report to post on the Forum when you are done. ^.^d
My dryer is easy enough to reach that joining the two air hoses together shouldn't be a big deal, if needed. But if mine was way aft hidden behind the hydraulic tank I probably would go to the trouble to install a remote valve or three.
I just did that when I was stuck in Rock Springs, WY last week, on my way from TX to Yellowstone :-)