150 psi rear tank? Emergency repair: Yes or no?

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150 psi rear tank? Emergency repair: Yes or no?

June 02, 2018, 09:09:25 pm

Hi,
On our first road trip. Rear tank air pressure reaches 150psi. Front tank at 110psi. Is the high rear tank pressure a critical issue? Compressor governor issue? Something else?

MOST IMPORTANTLY: Can we drive safely for a few days? 160 miles total until we have appointment at Oregon Motor Coach in Eugene on June 7th and 8th.

Thanks!!!!!!!

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #1 – June 02, 2018, 09:23:10 pm

My first guess would be a bad gauge. Both front and rear tanks are filled by your wet tank. So for your rear tank to be at 150psi the wet tank would also have to be at 150psi. Since the wet tank feeds both tanks if the wet tank is 150psi both tanks should be at 150psi.

If you can switch the connections on the back of the gauge to see if the high pressure follows.

see ya
ken

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #2 – June 02, 2018, 10:41:06 pm

I agree with Ken. First suspect is the transducer. You should have a blue box (maybe gray) in the dash spaces. Two of thr plugs are for the pressure gauges, easy to swap them there.

When the electronic gauges go and a new transducer doesn't fix it the easy and for many a better solution is to go to direct read mechanical gauges. They don't go to zero when you shut the ignition off

Yours may have air lines up into the dash are for this. Look for Drawing B2254. Rhe one I attached is the right build number range but is for a U320 with a tag. Probably close.

You should be OK. The tanks should be the same pressure.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #3 – June 03, 2018, 12:15:21 am

Thank you!

Peace of mind is worth more than I can tell you!!. Will tell OMC shop of issue and see if air pressure gauges will be available to install when we visit on the 7th. I prefer the direct reading air pressure gauges over the digital ones FT installed.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #4 – June 03, 2018, 08:37:34 am

Quote from: Mike J – June 03, 2018, 12:15:21 am

Peace of mind is worth more than I can tell you!

Peace of mind is knowing what is actually going on in your air system. If you have the coach in a shop where they are working on the air system, you might discuss the possibility of adding a wet tank mechanical air pressure gauge in the engine compartment. It is a fairly simple job, and the parts are inexpensive.

The D2 governor, which is located somewhere in your engine compartment, has a unused bottom port which constantly "sees" wet tank (reservoir) air pressure. You only need to run a air line from this port to a pressure gauge located in a place easily observed from the engine compartment hatch. Each coach will be laid out differently, but the basic concept is simple to implement.

Knowing your wet tank pressure can be helpful in diagnosing many air system problems. The wet tank is the first storage tank in the system. At the moment the air compressor unloads (air dryer purges) the entire air system should be at the same pressure, which will be indicated on the wet tank gauge. Comparing the wet tank pressure reading to the dash air pressure gauges can help pinpoint problems in the air system. Also makes it easy to verify and/or adjust your cut-out pressure on the D2 governor.

See the links below for a helpful diagram of the D2, and link to an old post showing my simple wet tank gauge installation.

Dash Air gauge has two indicators. one white, one red..

Haldex D2 Governor Service Data

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #5 – June 03, 2018, 12:20:38 pm

Quote from: Chuck & Jeannie – June 03, 2018, 08:37:34 am

Peace of mind is knowing what is actually going on in your air system.

Knowing your wet tank pressure can be helpful in diagnosing many air system problems.

Chuck,
I like your idea for the air system. I've been looking for ways to monitor/verify/diagnose the coach systems. Having the Vmspc has been great for the engine/transmission, but cannot monitor the air system.

Anything I can do to make sure the wheels keep on rolling safely is a big help in enjoying the ride.

BTW: Any easy way to have a low pressure warning on the front/rear tanks when the gauges are mechanical? (I'm assuming that without the "transducer" blue or gray box there will be no low psi warning)

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #6 – June 03, 2018, 01:08:43 pm

Quote from: Mike J – June 03, 2018, 12:20:38 pm

BTW: Any easy way to have a low pressure warning on the front/rear tanks when the gauges are mechanical?

You already have a low pressure warning - it is part of the HWH leveling system. On your rear 6-pack manifold there is a pressure transducer. It's purpose is to monitor system air pressure, and to activate a warning light and/or a audible alarm when pressure drops below the switch set point. The set point is usually around 80 psi. You might find the specific setting in your HWH Leveling System owner's manual.

When you first turn on the ignition key, all of the warning lights/icons on your dash should light up. There should be one that says something like "Leveling System" or "Air Pressure" or "Low Air Pressure". I haven't seen the dash on your model coach, so don't know specifics.

HMMmmm.... Your question got me looking through the archives. I may not be totally correct about how the low air pressure condition would be "announced" by your 2002 model coach, in the absence of the "blue box". Some of the other owners with newer model coaches might want to comment. Like perhaps Roger? See threads linked below:

Air Brake Low Pressure Warning

Mechanical Air Pressure Gauges

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #7 – June 03, 2018, 01:41:09 pm

Mike J, I went to mechanical gauges and do not get the alarm warning if low air pressure. I had to disconnect the alarm when went to mechanical because otherwise it thought all the time I had no air pressure.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #8 – June 03, 2018, 01:50:27 pm

Michael (& Jackie),

Do you have a "Level System" light or "Level" light on your dashboard? Does it stay on until your air pressure gets up to about 70 psi, and then goes off? If so, that would be the light controlled by the HWH rear 6-pack pressure switch. If it illuminates when you are driving down the road then that could serve as a visual low air pressure warning light.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #9 – June 03, 2018, 02:22:21 pm

On my coach if the Green Travel Light is on, I'm good to go. If the light is out, then something is wrong and the coach may not be in ride height.

Follow-ups
- Locate Solar Charge Controller on wall behind kitchen drawers?

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #10 – June 03, 2018, 02:33:35 pm

Quote from: John Morales – June 03, 2018, 02:22:21 pm

On my coach if the Green Travel Light is on, I'm good to go. If the light is out, then something is wrong and the coach may not be in ride height.

Right, John - that is the green "Travel" light on the HWH control panel. It is controlled by the pressure switch on the rear 6-pack. But there should also be another "Level" light (controlled by the rear 6-pack pressure switch) on the dashboard, . I'm just trying to determine if the newer coaches have that dashboard light.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #11 – June 03, 2018, 03:10:46 pm

Chuck, as other wrote, I have that green travel light on the HWH control panel by the driver left arm. Not good to go unless it lights, will lock me out. In my manual though it says to not trust that completely, that should go out and look at the coach to be sure it at ride height before heading down the road......I should but gotten into bad habit I guess of trusting the light.

That light is active when I am getting ready to go, for example if total air pressure too low. Or leaving and take coach out of level, it will come on and signal it ok to drive.

On the dash though I do have a light that comes on.....why do I not know when it does not or what means.....I cannot say it lights up if I lose enough air pressure while driving. At least it has not yet done that, thankfully. But it does note the level system is active, not sure if that is same as failing air system. A good thought about that message, Chuck. And it is not simply a green light but a couple of words. Just like similar for the park brake system being on.

Will see if I can find out more later today, maybe. Just in time crunch today.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #12 – June 03, 2018, 04:02:33 pm

Quote from: Chuck & Jeannie – June 03, 2018, 02:33:35 pm

Right, John - that is the green "Travel" light on the HWH control panel. But there should also be a light on the dashboard that indicates low air pressure. I'm just trying to figure out if the newer coaches have that dashboard light, and if so where it gets its signal.

Correct Chuck, I have a light on my dash that says low pressure, plus the alarm keeps sounding as long as the pressure is low.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #13 – June 03, 2018, 05:05:43 pm

Thanks, John.

So, if the OP's 2002 coach is the same, it should have two lights on the instrument panel that pertain to system air pressure. One is the "Level System" light that is controlled by the rear HWH 6-pack pressure switch. The other is the "Air Press" light that probably gets its signal from the "blue box" that powers the electronic air pressure gauges. If mechanical air pressure gauges are installed, and the "blue box" is disabled, then the "Air Press" light may no longer function (like in Mike H's coach). However, the instrument panel "Level System" light should still function, and it can serve, along with the annunciator (beeper), as a warning of low air system pressure.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #14 – June 03, 2018, 05:11:02 pm

Quote from: John Morales – June 03, 2018, 02:22:21 pm

On my coach if the Green Travel Light is on, I'm good to go. If the light is out, then something is wrong and the coach may not be in ride height.

Hey John, Chuck,

Not sure where you guys are getting your information from or if there are really differences year to year.

See attached picture of caution label that is on my left dash.

It states exactly the same caution in my owner's manual for this coach (2002) and for our previous (1998). My green travel light on the HWH Panel comes on at some much lower pressure than 80 psig, as in somewhere between 20 and 30 psig. I always understood that that sensor was on one or more of the HWH six packs, and simply means that the air bags are receiving air and it has built to some LOW pressure.
The caution to not move the coach is not as important on 2002's and after, because the frame is 2 or 3 inches taller and the wheels do not contact the overhead panels when the bags are low in pressure or completely aired down. With 2001 and prior coaches, if you move the coach when the green light comes on, you risk scuffing or destroying the panels overhead of (particularly) your rear axle(s).
There are several threads reminding Foreforum members of this. Haven't searched but should be easy to find.

Edit: Here you go:

Travel Mode

As far as the two "warning indications on the dash" go, I have only one air pressure associated warning light ("Level System") on the 2002 and had only one on the 1998. The Yellow "Level System" warning on the dash is simply a repeat of the green ""Travel" LED on the HWH Panel. If the ignition is on and the HWH senses less than 20-30 psig on the one (or maybe more) HWH six packs, the light and the alarm on the dash continue.

The DOT low air system warning (unadjustable pressure switch that acts at 62 psig decreasing) comes off of one (or more, maybe) of the pressure switches under the dash. There is no specific warning light on the 2002 dash, and I can't remember on the 1998, but the same warning "Bell/Beeper/Chime" under the dash is used to announce the low air pressure condition. It continues until air pressure under the dash reaches something greater than 62 psig.

HTH,

Neal

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #15 – June 03, 2018, 05:30:13 pm

Neal,

Your green travel light on the HWH panel may be suffering from "Premature Illumination"...a common condition in the elderly.

The page from the HWH Text Book that I linked above (Reply #6) states that "Pressure switches used to monitor system air pressure are usually set at 85 psi, although some manifolds have a pressure switch set at 100 psi." If that is the case, it should take close to 85 psi in the air system before the green HWH panel travel light comes on. On our coach, the green light comes on at about 70-75 psi, which I feel is close enough for government work.

The warning sticker in your photo repeats the same warning found in my HWH owner's manual. That is, seeing the green travel light illuminated DOES NOT mean the coach is at proper travel height and ready to move.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #16 – June 03, 2018, 05:49:20 pm

Neal, my green light comes on at about 90psi and the alarm goes off. I don't move my coach until I am fully aired up to 120psi. I never move the coach as soon as the Travel Light comes on.
John M

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #17 – June 03, 2018, 06:07:59 pm

Guys,
John, sorry. When you said "On my coach if the Green Travel Light is on, I'm good to go.", I was concerned that newbies would take that as a license to move a coach, which is not what the HWH "Travel" green LED is meant for.

Isn't/aren't the Green Light Pressure Switche(s) on the supply side of the HWH six pack manifolds? If the switches are on the bag side of the six pack manifolds, I didn't know that the bags always ran at greater than 85 to100 psig.
The point being, pressure on the inlet side of the manifolds tells us nothing about bag pressures and travel attitude around the four corners of the coach.
Neal

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #18 – June 03, 2018, 06:39:25 pm

Neal makes a good point. Have seen many coaches with "skid marks" in the top of their wheel wells.
I have done it myself, let air leak down then started coach and soon as alarm stops, try to move coach.
As said, think around the 2002 and up have different size stops, so coach will not drop far enough to allow wheels to contact top of wheel well. Think weight of coach and design of your HCV, as well as air pressure, will dictate how quick your coach will reach proper travel height.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #19 – June 03, 2018, 08:21:25 pm

Quote from: Neal Pillsbury – June 03, 2018, 05:11:02 pm

The caution to not move the coach is not as important on 2002's and after, because the frame is 2 or 3 inches taller and the wheels do not contact the overhead panels when the bags are low in pressure or completely aired down.

Would putting the taller stops "fix" my 2000, or were there other changes, too?

Thanks,

Trent

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #20 – June 03, 2018, 08:22:30 pm

Being used to having a Newell I'm in no hurry for it to air up. Which is pretty quick on a FT.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #21 – June 03, 2018, 11:29:00 pm

Quote from: TulsaTrent – June 03, 2018, 08:21:25 pm

Would putting the taller stops "fix" my 2000, or were there other changes, too?..........................

Trent,
Putting taller suspension stops on the frame rails only helps to keep the tires from crushing and/or deforming the overhead panel sheeting and flooring, especially when one is trying to auto-level with very uneven site conditions. I tried for years to get an answer out of FT on what height buttons I could add to the frame rails on the 1998 U270. I never got an answer.

The problem is that when the buttons are too tall and the coach is lightly loaded (i.e. - the air bags are going to be on the soft side, going down the highway), then you may well bottom out the suspension when you encounter severe surface conditions. It happened to us many times when running an essentially "Zero-Loaded", 1998, 36', U270 on frost damaged roads in New England.

The reason the 2002's and up don't have the tire/overhead scuffing problem is that as slides were added, the underlying frames had to be made taller and beefier to make up for the added weights and the weakened sidewalls, as well as the increased susceptibility to twist and stress crack at the corners of openings. So in 2002, you will notice that the distance from the entry step to the second step into the coach is a full three (+) inches higher than in 2001 and earlier. That's all in increased frame rail depth and the frame rails are stronger material as well. The beefed up frames also mean less susceptibility to sidewall anomalies associated with bulkhead weaknesses, partially countering the mythical favoritism shown to 2001's as THE premium year coach. Without the end cap issues forfeiting the MANY gains made over a 2001, I would much rather have a 2002, 3, or 4, due to the frame improvements, especially if it's a non-slide in those years. But that's why we have the coach that we do. However, this is all just personal preference. We all know that they are all good up through 2005 or so --- which is another whole world of discussion and personal preferences.

Simple answer to your question: NO, frame buttons are not likely to help you much in "Quick Getaway Situations". Also, they are somewhat "iffy" to use, especially on a lightly loaded coach.

HTH,
Neal

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #22 – June 04, 2018, 01:16:23 pm

Tulsa (regarding installing higher frame stops)
The other factor not mentioned here, yet, is that increasing the height of the metal frame stops with metal would increase the risk of metal to metal contact when the suspension bottoms out - this is very undesirable because it will cause permanent damage to the suspension components. If a bottom out incident occurs, there will be little damage if it happens with rubber components (i.e. the rubber stopper inside each airbag) which is designed to stop over compression of the air bag. I installed half inch spacers on top of each air bag so that, when on level ground with coached lowered as low as it will go, there is a very small gap between the top of the tire and the floor. If not on level ground, some tires will still touch the floor when coach is lowered. I also raised the ride height by 3/8 inch. I wanted to raise it a half inch, but adjustment bolts were not long enough.

If you decide to increase the height of the metal frame stops, be sure to use rubber rather then metal.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #23 – June 06, 2018, 02:24:40 pm

Gentlemen,
All the green travel lite tells us is that the 85psi switch on the rear HWH manifold has sensed 85 or more psi in the air system.
That switch only has two functions, less that 85psi and it turns the low air pressure warning system on. More than 85psi and if the key is on and the level system is off then the HWH computer will send 12 volts to all the travel solenoids (and the green travel lite comes on ) to hold them open so the ride height control valves can set the coach at the travel height.
Just because the green travel lite is on does not mean all travel solenoids have opened. The only way to confirm travel height is to take that last walk around and look at the height of each corner.
At this point since the engine is running you have a chance to see if anything is running out of the bottom.

Re: 150 psi rear tank? Emergency repair: Yes or no?

Reply #24 – June 06, 2018, 03:28:09 pm

Does this mean that one would be able to drive a 02 or later if a air bag should go out?

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