Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Mike J on August 14, 2018, 06:49:43 pm
Title: Air dumping from rear under acceleration.
Post by: Mike J on August 14, 2018, 06:49:43 pm
Have read a bunch of HWH posts. Couldn't find this issue exactly. Please let me know if there is such a thread.
Work just completed: New air dryer complete, also repaired 14 air leaks which included six pack o-rings, regulators, drain valves. Inspected air system including bags, steps, fittings etc. Linkages to ride height valves okay. Replaced electronic air gauges with mechanical. I believe air pressures are good, front and rear, 100-130, steady. Only drop in pressure is nominal as expected with braking.
On final test drive this morning: coach loudly exhausts 6-10 seconds of air from rear leveling valves when under 100% acceleration from a standing start. Also can hear valves exhausting every 1-2 seconds while driving at speed, 40-60 and also when moving at parking lot speed. Tank pressures remained constant. While watching coach in a parking lot I observed rear moving up and down 1-2 inches in sync with the 1-2 second exhausting air cycle. Sound of air exhausting is same as when dumping. Inside coach it can be heard as coming from the ride height valves. The rubber boots on bottom of valves are missing and I guess must have been for some time. No debris, obstruction there etc.
All functions of leveling, travel mode, raise and dump perform normally. All engine temps etc. normal. Using Silverleaf to monitor them. Guys at shop not sure what gives, HWH CAN, control panel or ride height valves. (belief is something HWH electrical linked to accelerator ECM? and not ride height valves nor air compressor, governor)
What would cause a 6-10 second dumping from rear air bags when coach is accelerating hard, or 1-2 secs cycling air exhaust under mild acceleration?
Title: Re: Air dumping from rear under acceleration.
Post by: Pamela & Mike on August 14, 2018, 07:26:03 pm
Mike,
When you say "rear leveling valves " and "ride height valves" are you using the same term for the ride height valves? If so, have the ride height valves been changed out? If they have been changed out they may have used 2 with no center "dead band" this would cause them to react too quickly. After re reading they may have not got the ride height valves centered up properly when they were working on the linkage. (there is a center mark on them kind of like a mark in a timing gear) Now this is just 1st guess need to think about this some more.
If it is the ride height valve exhausting this is really separate from the HWH. As all the HWH does in travel mode is open a valve to supply air to the ride height valves.
Pamela & Mike
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 15, 2018, 12:05:52 am
Hi Mike,
Apologies for poorly written post. Ride height valves have not been changed out. I assume the rear leveling valves are actually the six pack of the HWH system. ??? 4 sets of o-rings on six pack were replaced. Two of the 6 pack solenoids had no leaks.
Tomorrow we will wire separate indicator lights into each circuit at the 6 pack solenoids that energize the left/right dump function. Bring the leads up into bedroom and test drive to see if HWH is sending 12v to energize these solenoids. We don't know if problem is just one or both solenoids, or problem is further upstream to HWH rear CAN.
At some point we are also going to remove the brown connector in the HWH rear CAN to isolate the valves. At least this is what I've been told and my recall is fuzzy given this has been a very long day. Removing the connector is one of the tests i have read about on the forum and it was also suggested by James at FOT and a tech at HWH.
We're hoping it isn't the CAN. I've been told that HWH takes 3-4 weeks to rebuild one. We don't want that to be the only option. Starting two weeks ago, my wife took a medical leave of absence due to my health so we can spend time together traveling some. We are currently on the road. A 3-4 week delay blows a very big hole in our journey. If it is the CAN, is there any other quicker place to get a replacement??
Title: Re: Air dumping from rear under acceleration.
Post by: floridarandy on August 15, 2018, 01:27:14 am
Michael...fingers crossed on next round of trouble shooting.
Title: Re: Air dumping from rear under acceleration.
Post by: Pamela & Mike on August 15, 2018, 06:53:31 am
Mike,
If the system was not exhausting before this work was done lets take a step back and look at what has changed. You need to determine if the air is exhausting out of the ride height valves or out of the exhaust port on the rear 6 pack. If it is the ride height valves working against each other the linkage has been misadjusted when they were checking them. If it is coming from the 6 pack exhaust port then they need to find out which wire plug they transposed when they had the air solenoids apart to install the new "O" rings. All those wire connections can be swapped between each other and they will only work correctly in one order. The lights will tell you which valve has the wrong signal but the proper wiring diagram for your system along with the wire markers (hopefully they are still there on the wires) are your best bet for getting this fixed. I would bet that they have 2 wire plugs (each plug has 2 wires) on the rear 6 pack solenoids transposed if it isn't the ride height valves.
What CAN are they talking about? If they are talking about the 6 pack manifold it don't just go bad overnight (unless they cross threaded one of the valves) as it is just an aluminum block that has been drilled, ported, milled.
Mike
Title: Re: Air dumping from rear under acceleration.
Post by: Protech Racing on August 15, 2018, 10:06:05 am
Wire or airline swapped . Sounds like the HWH is fighting the ride height valves.
Title: Re: Air dumping from rear under acceleration.
Post by: wolfe10 on August 15, 2018, 10:12:35 am
But, the HWH system should not be "active" when in travel mode.
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 15, 2018, 01:41:20 pm
But, the HWH system should not be "active" when in travel mode.
This is the reason he needs to find out exactly where the air is coming from then go from there. Something has been swapped either air or power while the system was down for repair.
Mike
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 15, 2018, 04:20:19 pm
Checking now to see if connections at six pack were swapped. Anything possible but doubt it. 1.) Procedure at OMC is to do one valve at a time to avoid wrong connections. 2.)The leveling functions, front to rear, side to side, including raise and dump work properly when parked and when engine is running. Dumping of air from rear is only repeatable under hard acceleration, occasionally at lower speeds. Weird. We did unplug the CAN for the rear pack and the problem remained. Also problem remained when CAN was reconnected to pack. Meaning something mechanical happening?
On this coach the six pack exhausts through the ride height valves. There are no exhaust ports on the six pack. No work was done on the ride height valves.
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 15, 2018, 04:26:48 pm
But, the HWH system should not be "active" when in travel mode.
Hi Brett, On our coach the raise and dump can be accessed when in travel mode as long as 5-10 mph speed is not exceeded. If speed is exceeded coach returns to travel mode. Wouldn't this indicate that the HWH is active in travel mode. But only for raise and dump.
As I write this I wonder if the transmission speed sensor is causing this rear dumping under acceleration? Grasping at straws here. Thanks!
Title: Re: Air dumping from rear under acceleration.
Post by: Pamela & Mike on August 15, 2018, 05:17:59 pm
On this coach the six pack exhausts through the ride height valves. There are no exhaust ports on the six pack. No work was done on the ride height valves.
Mike,
This may be your problem. The exhaust port on the aluminum block could be stopped up with a durt daubber nest. I have never seen a coach that doesn't have a exhaust port on the aluminum block. It is hid behind the pressure switch. This would be the first coach that I have ever herd of to do this as you will need a special ride height valve and piping to achieve this action.
On this coach the six pack exhausts through the ride height valves. There are no exhaust ports on the six pack.
Mike J,
I agree with the other Mike (Pam&Mike) - I have never seen a 6-pack manifold that does not have exhaust ports. I can't imagine how the 6-pack exhaust function could be incorporated into the ride height valve. It would take a very complicated valve to do double duty. BUT, I'm not all that familiar with the 2000+ model year coaches, so I could be wrong.
Link below to the HWH Leveling System Textbook. If you have not seen this document, it may be helpful in solving your puzzle. Note that all the diagrams of the various rear 6-pack manifolds used in different HWH Series systems show exhaust ports (unless I overlooked one).
https://www.hwhcorp.com/ml20635.pdf
Title: Re: Air dumping from rear under acceleration.
Post by: rbark on August 15, 2018, 07:32:18 pm
I also agree with Pam and Mike. There's got to be exhaust ports on the 6 pack blocks.
Title: Re: Air dumping from rear under acceleration.
Post by: Don & Tys on August 15, 2018, 10:52:09 pm
Perhaps a shot in the dark, but did they disconnect the linkage on the ride height valve? If so, and if they lined up the index marks on the valve body 180º off, the valve will exhaust air when they should be adding it and vice versa. This only affects the coach in travel mode. If only one of the valves had the linkage 180º off, the coach would drop on that side. I don't know if the effect would be as you described, but I thought I would mention it. Don
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 15, 2018, 11:32:52 pm
Yes on exhaust ports on six pack. My lack of HWH knowledge showed itself again! I got confused in conversation with tech here regarding where the system exhausts and/or dumps air from, six packs and ride height valves. Throughout this odd problem all HWH connected systems, level, travel mode, dump and raise have worked as they should. Also the new dryer purge valve would exhaust once front/rear tanks reached proper psi.
This is our diagnostic path to what I hope may be a solution: 1.) First replaced the ride height valves. The originals had lost their protective caps over the exhaust port. 2.) Tech support at HWH suggested that one or both of dump solenoids could be weak and allowing air to be released when the rear air bags become slightly compressed under acceleration. Everyone felt that to be a bit of a longshot but saw it as another way to narrow the possibilities. Especially since the packs had been serviced for leaks. Fortunately the air exhaust holes are threaded and so we plugged them for another test drive. 3.) With no air escaping and with the ride height valves replaced another source of air escaping became clear. The new Haldex air dryer, (installed 2 days ago) came with a faulty safety valve. The new mechanical air gauges on the dash indicated air being dumped then building quickly. 4.) Repair techs removed the plugs from the six pack exhaust ports, removed the dryer safety valve and plugged that hole. Another test drive and no air was exhausted during hard acceleration like before.
Tomorrow new safety valve gets installed in dryer then another test drive. At same time I want the ride height adjustments checked for Foretravel specification. We may have found the solution to our air exhaust/dump mystery during acceleration. If so, we made a classic mistake: We assumed that every new part we initially installed was also a good part.
Does anyone know the psi specification for the safety valve on a Haldex dryer? I'd like to be sure we get this right. And what are the correct ride heights for 2002 U270 travel mode, I assume this is measured at the air bags?
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 15, 2018, 11:37:10 pm
Perhaps a shot in the dark, but did they disconnect the linkage on the ride height valve? If so, and if they lined up the index marks on the valve body 180º off, the valve will exhaust air when they should be adding it and vice versa. This only affects the coach in travel mode. If only one of the valves had the linkage 180º off, the coach would drop on that side. I don't know if the effect would be as you described, but I thought I would mention it. Don
Thanks Don, the ride height valves are now replaced so I will check on this tomorrow. I think they are installed correctly but coach had some slight listing to one side when I saw them leave on final test drive of the day. Definitely want the ride height adjustment checked
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 22, 2018, 11:16:15 pm
I'm happy to post that the air dumping has been solved. It was a headache for the service techs. They installed two newly rebuilt air dryer assemblies and both did the same dumping of air. Got my old OEM unit, serviced it and reinstalled. No more air exhausting during acceleration. Discovered that our original dryer had a 200 psi safety valve on dryer. The units delivered to us as replacements had a 175 psi. Another note: Trying to diagnose this they also replaced the rear ride height valves. One of those was defective.
The good news is my final bill for this work will be adjusted to reflect the bad parts and or decisions that were made. I can't say enough good things about Oregon Motorcoach Center. They have handled this well. Coach rides at right height and sits as it should. And we are now heading north on 97 towards Idaho.
My next forum search will be what members do to replace dryers for the discontinued Haldex model in our coach. I expect that someday the OEM dryer, purge valve and the internal air passages, ball checks, springs will need service.
Thanks to all of you who gave this some thought. The forum brain trust is a huge help as I learn what our coach is about.
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 22, 2018, 11:33:41 pm
Discovered that our original dryer had a 200 psi safety valve on dryer. The units delivered to us as replacements had a 175 ps
I don't think you could ever see 175 psi anywhere in your air system, much less 200 psi. You should have a safety valve on your wet tank that will open at about 150 psi.
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 23, 2018, 12:05:16 am
I don't think you could ever see 175 psi anywhere in your air system, much less 200 psi. You should have a safety valve on your wet tank that will open at about 150 psi.
Yes, our tank psi peaks at about 150. That psi shows in the rear tank gauge, (mechanical) and the front tank is less, about 135. The air safety valve on dryer is, I assume is on the inlet side coming from the compressor. Are you suggesting there may be a high psi issue between the compressor and air dryer? We do hear air dryer exhaust briefly every 5-10 minutes depending on roughness of road and how much we are applying the service brakes.
Title: Re: Air dumping from rear under acceleration.
Post by: John44 on August 23, 2018, 05:37:42 am
The D-2 valve regulates your air pressure,150 seems a little too hi,would check the gauge.There has been alot of discussion about the hyd fans using horsepower,the air compreesor uses some horsepower too,the lower the pressure the less HP it will use.
Title: Re: Air dumping from rear under acceleration.
Post by: Pamela & Mike on August 23, 2018, 07:25:40 am
Mike J,
Just to clear up some confusion as to tank location and terminology so we are all talking about the same thing. As I read this thread it seems like we are talking about a couple of different things. If we can clear this up it will help me think things through and help other members out as to what they have.
You have 3 air tanks
1. The "wet tank" (term used before the time of air dryer but the name has just stuck) Chuck is talking about has no gauge unless someone has added one. This tank is located mostly above the rear end housing on most coaches of your vintage. It's pressure will be diffrent than what you see on the front/rear tank gauges due to various things like hose runs, check valves, & fittings.
2. The rear tank that has an OEM electronic gauge that you have changed to mechanical 3. The front tank that has an OEM electronic gauge that you have changed to mechanical Both the latter 2 tanks are mounted right below the 2 front seats and this is where your gauges have there taps. These tanks are fed through one line from the wet tank should be piped parallel. Now with that being said they will always be slightly diffrent in pressure due to hose runs, check valves, & fittings between the 2 tanks.
As has been stated that pressure is somewhat high at 150.
Mike
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 23, 2018, 08:34:55 am
Yes, our tank psi peaks at about 150. That psi shows in the rear tank gauge, (mechanical) and the front tank is less, about 135. The air safety valve on dryer is, I assume is on the inlet side coming from the compressor. Are you suggesting there may be a high psi issue between the compressor and air dryer? We do hear air dryer exhaust briefly every 5-10 minutes depending on roughness of road and how much we are applying the service brakes.
We don't want to keep bringing things up that cause you concern about your coach - I know you guys are trying to get off on a relaxed, enjoyable outing. But when you mention things in a post that sound a little "off" to us, we feel obligated to speak up. In this case, the air pressure readings you report seem a little high.
I will expand on Mike's description (above). Picture a very simplified air system. There is a air compressor with a big hose leading to a air dryer. From the dryer another hose leads to the "wet" tank. From the "wet" tank a hose runs up to the front of the coach, where it splits and feeds into two more tanks, the "front" tank and the "rear" tank. Air can flow freely from the compressor, through the dryer and the "wet" tank, to the "front" and "rear" tanks. It should not, however, flow backwards due to check valves in the system. These check valves are located at the air compressor and at the inlets for all 3 tanks.
Air pressure in the system is regulated by the D2 governor. For detailed explanation, see link below. In simplified terms, during normal operation your air system should cycle between a low and a high pressure. Low pressure on our coaches is normally around 90-100 psi, and high pressure around 120-130 psi. When the high pressure is reached, the air dryer purges (blows off). At that moment, the pressure in all 3 air tanks should be almost identical. After that, tank pressures may diverge, depending on what components are operated off which tank.
Your air dryer purging every 5-10 minutes while driving sounds normal - no worries there. ^.^d
What sounds ODD to us is when you say one tank (gauge) peaks at 150 psi and the other tank (gauge) peaks at 135 psi. They both should read the same pressure when the dryer purges. The other odd thing: 150 psi is a little higher than normal max pressure. This max system pressure can be adjusted at the D2 governor. The pressure differential between low and high pressure is a fixed range (usually about 20-30 psi), but you can adjust the high pressure point up and down at the D2. See the link below for the instructions.
Haldex D2 Governor Service Data (http://beamalarm.com/Documents/haldex_d2_governor_service_data.html)
Title: Re: Air dumping from rear under acceleration.
Post by: John44 on August 23, 2018, 10:14:44 am
Mike J,with all the trouble you have had I would just get a new D-2 valve and install it,they are availible everywhere and is one of the parts you should have a spare for.They are usually preset at 120 to 130 psi so you should never have any pressure more then that.
Title: Re: Air dumping from rear under acceleration.
Post by: amos.harrison on August 24, 2018, 10:01:35 am
With different pressure shown on the gauges, check with a portable pressure gauge. That 150psi reading gauge may be bad.
Title: Re: Air dumping from rear under acceleration.
Post by: Caflashbob on August 24, 2018, 05:42:22 pm
My understanding is that the max D2 is 135.
Is not the DOT max on fittings 150?
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 25, 2018, 02:34:18 pm
Mike J,with all the trouble you have had I would just get a new D-2 valve and install it,they are availible everywhere and is one of the parts you should have a spare for.They are usually preset at 120 to 130 psi so you should never have any pressure more then that.
Thanks all. We are heading towards Moscow Idaho today. Flat roads and easy drive on route we have chosen. Good time for me to get an accurate read on the air pressures in front and rear tank. My better half is doing all the driving and when we were in the mountains she wasn't watching the air all that closely and my view is at an oblique angle. (We do not have a gauge on the wet tank.)
D2 valve is now on my list. Will see where I can get one as spare/installed if front or rear tank pressure is really as high as 150psi. After reading Beamalarm link it is surely time to service/replace it given mileage and/or time. I'm pretty sure that current one is the OEM from 2002 coach build as there are no records from PO on replacing it.
Other info: After 24 hours both front/rear tanks read 40psi. No aux compressor run time either. Fixing leaks in six packs and other fittings/regulators seems to be keeping us parked level. Coach wouldn't do that before. Previously dropped in front.
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 25, 2018, 03:04:12 pm
Other info: 1. After 24 hours both front/rear tanks read 40psi. 2. No aux compressor run time either 3. Fixing leaks in six packs and other fittings/regulators seems to be keeping us parked level.
If your air system bleeds down to 40 psi in 24 hrs, you do still have some leaks, somewhere. Not something you necessarily need to worry about - lots of coaches will do the same exact thing. it's just a question of how much time/money/effort you want to devote to chasing small leaks.
Your aux compressor is not running because your coach is remaining level when parked. The compressor will run if your system air pressure is low AND if the HWH control box thinks it needs to increase the pressure in one or more bags to keep coach level.
Replacing the D2 regulator certainly won't hurt anything. NAPA stores will always have them in stock. R&R can be a simple job, or a difficult job, depending on the location of the D2. Having a spare D2 in your parts box is a very good idea. They seem to always act up at inconvenient times and places.
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 26, 2018, 09:42:26 pm
The 150 psi and air purging intervals I reported in my previous posts was incorrect. My apologies! New mechanical gauge faces are numbered differently. Regardless, that's no excuse for misreading the new gauge. Feeling like a newbie.
Confirmed following during a 20 mile run yesterday. Level ground, 58-60 mph, usually on cruise, approx 1550rpm. With a stopwatch I timed the purging of air and watched closely the psi levels. Air exhausts at 128 psi every 1.5-2.5 minutes. On rougher road the interval between purges increases to 3-3.5 minutes. Front tank stays pretty consistent at 110-120. It will drop to 95-100 before climbing again to 110-120. The rear tank has the largest swings and they are not always in sync with psi in the front tank. Rear tank drops to 95 then rises to 128 before we hear air is purged. Sometimes the front will vary 100-120 while the rear goes from 95-128. No inverter or service brakes were applied during this test run.
Selected travel mode at start up, cold engine idle: both tanks build pressure within 5 psi of each other. Once at travel mode, the front tank psi moves very little off of 110-120, however the rear tank cycles. At warm engine idle it takes 4.5 minutes for pressure to drop from 128 to 90 psi. Pressure takes 1 minute to build from 90 to 128 psi. Have noticed a louder noise (a kind of metallic clatter different from my memory of the sound of Cummins idling). Sound more pronounced after engine warms up. Comes from rear of coach, most noticeable in bedroom area just behind rear axle. Sound builds as the psi approaches the 128 psi purge level and also when approaching the lowest psi of 90. Easy to hear when coach is idling as compared to when driving.
We leveled the coach, allowed tank pressures to build and shut down engine immediately after air purged. Within five minutes rear tank psi dropped from 128 to 60. Front tank stayed at 110 psi. Twenty minutes later front at 100 and rear at 60psi.
Now in Moscow Idaho, will run errands tomorrow in the toad. Look for a D2. Would appreciate a NAPA part number. I'll check for one online as well in case no one replies here before tomorrow. Not sure where to find someone who can install it correctly and/or if it will have proper psi levels preset. (should be on the part or box?) I recall forum members saying this replacement is easy. I'm not as confident given I have to rely on others to do the wrench turning.
Truly appreciate all the help. We both are looking forward to having these air issues behind us. Being newbies it is disconcerting, listening for anything unusual. The learning curve is stressful at times. Sorry for the lengthy post.
Title: Re: Air dumping from rear under acceleration.
Post by: craneman on August 26, 2018, 09:51:24 pm
The 150 psi and air purging intervals I reported in my previous posts was incorrect. My apologies! New mechanical gauge faces are numbered differently. Regardless, that's no excuse for misreading the new gauge. Feeling like a newbie.
Confirmed following during a 20 mile run yesterday. Level ground, 58-60 mph, usually on cruise, approx 1550rpm. With a stopwatch I timed the purging of air and watched closely the psi levels. Air exhausts at 128 psi every 1.5-2.5 minutes. On rougher road the interval between purges increases to 3-3.5 minutes. Front tank stays pretty consistent at 110-120. It will drop to 95-100 before climbing again to 110-120. The rear tank has the largest swings and they are not always in sync with psi in the front tank. Rear tank drops to 95 then rises to 128 before we hear air is purged. Sometimes the front will vary 100-120 while the rear goes from 95-128. No inverter or service brakes were applied during this test run.
Selected travel mode at start up, cold engine idle: both tanks build pressure within 5 psi of each other. Once at travel mode, the front tank psi moves very little off of 110-120, however the rear tank cycles. At warm engine idle it takes 4.5 minutes for pressure to drop from 128 to 90 psi. Pressure takes 1 minute to build from 90 to 128 psi. Have noticed a louder noise (a kind of metallic clatter different from my memory of the sound of Cummins idling). Sound more pronounced after engine warms up. Comes from rear of coach, most noticeable in bedroom area just behind rear axle. Sound builds as the psi approaches the 128 psi purge level and also when approaching the lowest psi of 90. Easy to hear when coach is idling as compared to when driving.
We leveled the coach, allowed tank pressures to build and shut down engine immediately after air purged. Within five minutes rear tank psi dropped from 128 to 60. Front tank stayed at 110 psi. Twenty minutes later front at 100 and rear at 60psi.
Now in Moscow Idaho, will run errands tomorrow in the toad. Look for a D2. Would appreciate a NAPA part number. I'll check for one online as well in case no one replies here before tomorrow. Not sure where to find someone who can install it correctly and/or if it will have proper psi levels preset. (should be on the part or box?) I recall forum members saying this replacement is easy. I'm not as confident given I have to rely on others to do the wrench turning.
Truly appreciate all the help. We both are looking forward to having these air issues behind us. Being newbies it is disconcerting, listening for anything unusual. The learning curve is stressful at times. Sorry for the lengthy post.
You have a leak in the rear. The D-2 is not the problem. Your protection valves are what stops the rear at 60psi. Run the engine and get the pressures up to the cutoff and shut off the engine. Go to the rear and listen for air escaping. If you cant hear it, get a squirt bottle and put some dish soap and water in it and start spraying the air bags etc.
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 26, 2018, 10:54:46 pm
D2 governor NAPA part numbers, either one would work fine:
https://www.napaonline.com/en/p/TWRBENOR284358X
https://www.napaonline.com/en/p/TWRBENOR275491X
Title: Re: Air dumping from rear under acceleration.
Post by: TulsaTrent on August 26, 2018, 10:56:26 pm
We leveled the coach, allowed tank pressures to build and shut down engine immediately after air purged. Within five minutes rear tank psi dropped from 128 to 60. Front tank stayed at 110 psi. Twenty minutes later front at 100 and rear at 60psi.
Yes, like The Other Chuck says, you are losing air out of your "rear" tank. Not the "wet" tank, which is in the rear, but the "rear" tank, which is in the front. ;) Your air compressor is cycling in and out more rapidly than would be normal because it is having to keep up with the air leak. You can drive this way - you are not going to damage your air compressor. As long as the compressor can still build to cut-out pressure, you are OK. If the leak were to become more serious, to the point that the compressor could never reach cut-out pressure but just ran continuously, then you would for sure need to get the leak fixed. But for now, you can live with it until it is more convenient to get it looked at.
It sounds like your D2 governor is working fine. I agree with The Other Chuck, don't think you need to worry about changing it out at this time. If you want to buy one to carry as a spare, some NAPA part numbers are listed in reply #30 above.
The best way to approach looking for any leak, is to first get out your air system diagram. You need to look at what lines come off the "rear" tank...where does the air go. Then you have to think about each place the air from that tank is used, what path the air follows to get there, and try to figure out best way to check for leaks. It is not easy, especially as you say if you have to depend on mechanics who may not be familiar with the air system on your coach.
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 26, 2018, 11:26:25 pm
I already knew that. Because of the unusual city name, I was pointing out that he could get service from the factory, in another city named the same, but several states East of his location.
Many Foretravel owners, including me, have benefited from taking their Foretravels to HWH, in Moscow. I was suggesting that he might benefit from making an appointment with them as part of his travels.
He is one of our newer members and may not have known about HWH. He may not be able to do that during his current trip.
I probably should have found a link to HWH factory discussions on the forum, but am beginning to lose interest in this topic; it is past my bedtime.
Trent
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 27, 2018, 08:15:47 am
OK, sorry! Mike J is already getting so much info overload - I didn't want him to confuse the 2 cities. Your idea about swinging past the HWH home office is excellent, if there is any way he could include the stop in this trip. Or the next one.
Here is one report on a HWH factory visit. There are others - all have a similar complimentary tone.
Good Experience with HWH in Moscow, Iowa (http://www.foreforums.com/index.php?topic=18564.msg127837#msg127837)
Title: Re: Air dumping from rear under acceleration.
Post by: TulsaTrent on August 27, 2018, 08:32:47 am
I found out about Moscow ID on our recent trip to Yellowstone. Someone we met was going from there to Moscow; I assumed he was talking about Moscow OH, but not. Wonder how many states have cities named Moscow; and why?
Trent
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 27, 2018, 08:39:03 am
Wonder how many states have cities named Moscow; and why?
Lots of Russian immigrants to this country back in the city naming days?
Here's another (better researched) attempt to answer the question:
Solving the mystery of the Moscows of America (https://www.pri.org/stories/2016-03-10/there-are-more-20-towns-america-called-moscow-why)
Title: Re: Air dumping from rear under acceleration.
Post by: Roger & Susan in Home2 on August 27, 2018, 08:49:11 am
Here is a bit of early morning bandwidth for breakfast.
One source says there are 18 cities known as Moscow in the United States: - Moscow, Idaho - Moscow, North Dakota - Moscow, Maine - Moscow, Kansas - Moscow, Texas - Moscow, Arkansas - Moscow, Iowa - Moscow, Minnesota - Moscow, Wisconsin - Moscow, Michigan - Moscow, Indiana - Moscow, Ohio - Moscow, Kentucky - Moscow, Tennessee - Moscow, Mississippi - Moscow, Virginia - Moscow, Maryland - Moscow, Pennsylvania If you count places that smaller then apparently 21.
There are only 18 places named Hastings in the US. Go figure.
There is one place in the world named Nacogdoches!
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 27, 2018, 02:18:53 pm
Good morning.
Roger, So many Moscows! I'll get out the Garmin and see if we can visit all of them. I enjoyed having a good laugh this morning after reading your post. I think a visit to HWH in Iowa would be smart. Have to see where it fits. We're hoping our 2 remaining months of traveling don't become a journey to service centers instead of touring the country.
I agree the rear tank is place to start looking, (which I know is mounted in front). Any connection on/to it as well as where those lines come from and those connections. Doubt it could be an airbag as coach does travel mode correctly and it levels properly as well. This morning psi at 42 in both front and rear tanks. Before recent repairs the coach used to drop in front within a day and rear settled in a week and we rarely heard dryer purge during driving. Fixed 14 leaks and we now stay level for several days without aux compressor ever running and air dryer does purge often enough, 2-3 minutes, to notice it while driving.
What am I missing? Appreciate everyone's input! I sure would like to know why leakdown in rear tank is most evident with engine compressor running and also when coach is first leveled and both tanks are at maximum psi. With engine warm, where does the clattering/chatter noise come from at the low and high, (louder) end of air psi range. And why is rear tank leakdown most evident when psi reaches level where air dryer purges.
Thanks! (I'm not looking to fix all leaks. Just think this leakdown in rear tank seems worth finding)
Title: Re: Air dumping from rear under acceleration.
Post by: Pamela & Mike on August 27, 2018, 03:39:11 pm
I sure would like to know why leakdown in rear tank is most evident with engine compressor running and also when coach is first leveled and both tanks are at maximum psi. With engine warm, where does the clattering/chatter noise come from at the low and high, (louder) end of air psi range. And why is rear tank leakdown most evident when psi reaches level where air dryer purges.
Mike,
First thing that comes to mind is the check valve that is at the rear tank has failed and is leaking back through. This check valve is where the air line goes into the tank boss. You may also have the internal check valve at the dryer discharge that has been installed up side down (yes even on a fresh factory rebuilt dryer I have seen it happen) causing the air to backfeed out to atmosphere through the drain on the dryer.
Mike
Title: Re: Air dumping from rear under acceleration.
Post by: craneman on August 27, 2018, 03:41:28 pm
Have you been to the engine compartment during the start and stop of the compressor? The unloader valves in the compressor could be making the noise. It would not cause the leak though. The compressor stops making pressure at the top end and doesn't start again until the low end. I have had a belt on my air compressor make such a noise also.
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 27, 2018, 07:03:23 pm
Went to engine compartment to check sound of compressor. Ended up finding a fairly loud air leak behind drivers side rear duals. Leak is very easy to hear standing next to coach after turning engine off. Can hear it for at least 10 minutes. Seems to come from where ride height valve is or possibly further in toward center of coach. Can't reach in there with soap spray, there is a storage compartment blocking access, unlike easy access on passenger side where air dryer and chassis battery are.
Noises, clattering rattle still present. Metallic sound. Stops clatter/rattle when air dryer purges.
Tomorrow taking it to a heavy equipment shop to see where air leak is. Only option that is close to our location.
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 27, 2018, 07:34:13 pm
First thing that comes to mind is the check valve that is at the rear tank has failed and is leaking back through. This check valve is where the air line goes into the tank boss. You may also have the internal check valve at the dryer discharge that has been installed up side down (yes even on a fresh factory rebuilt dryer I have seen it happen) causing the air to backfeed out to atmosphere through the drain on the dryer.
Mike
It would be very surprising to me too if the internal check valve is upside down. The air dryer we now have installed is the original OEM Haldex Pure Air. Only the filters/desiccant were changed out, (done about six months ago). The new/rebuilt dryers we had tried two weeks ago had wrong psi purge valve installed. They caused the original problem of this thread.
Thinking new leak we found today has different origin. Somebody will be under there tomorrow with a soap spray looking for bubbles. Will also ask what they think of clattering noise before dryer purges. Coach staying level now even after new leak ceases to be heard. F/R tank at 45 psi.
Title: Re: Air dumping from rear under acceleration.
Post by: Protech Racing on August 27, 2018, 09:35:46 pm
The noise is the unloader valve most likely and should stop when pressure is requested by the pressure controller D 2 . Check for a compressor line hose leak into the dryer . Or the unloader line .
Title: Re: Air dumping from rear under acceleration.
Post by: Chuck & Jeannie on August 27, 2018, 10:43:09 pm
Regarding the air leak near driver side duals...I'm just guessing here...
Do you have a remote mounted wet tank water drain valve? On our coach, the drain valve is mounted just ahead of the driver side duals, on the bottom edge of the wheel well. If yours is in the same general location, perhaps the nylon air line running from the wet tank to the drain valve was damaged in some way, and is leaking. A leak in that line would bleed air pressure off the wet tank, and could also bleed air pressure off the "front" and/or "rear" tanks, if the check valve at the tank inlet is faulty (a not uncommon condition).
Title: Re: Air dumping from rear under acceleration.
Post by: Mike J on August 31, 2018, 09:33:20 pm
Hi Chuck,
Good idea to check remote drain line.
For now, found two problems. Had airline run to coach rear 4 months ago for the air M&G brake system on our toad. Shop did sloppy job. ran airline under cross member of frame that rises and falls as suspension travels. The line would occasionally touch rotating portions of driveline. Leak just happened to show up three days after we thought we were done with the air dryer issues. Had repair done on location where we are parked by heavy farm equipment mobile service tech out of Moscow Idaho.
Air to toad is now routed with other cables along frame and then tied to existing brake can supply lines. We had to add about two feet of hose. It will now flex along with all the other lines as suspension travels. 2nd problem he found was a fitting on ride height valve that wasn't holding airline properly. Replaced it. We hope we are done now. Test drive this Saturday when we go to fuel up in town. I'll post results then.