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Old 07-09-2010, 08:12 PM   #29
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If there was oil in the air drier desiccant, I'll postulate an alternate theory as to how it gets there- the air compressor doesn't act the same under load to the engine as at idle or rev'd in neutral, and under some condition pushes oil into the compressed air stream. I have no specific reason to believe that other than I can't visualize how a serious accumulation of oil would otherwise end up in the desiccant.

Sounds like regular change-out & monitoring of the desiccant cartridge would alleviate or perhaps fix my theory.

As to an air pressure gauge, I put one in a customer's rig the other day for a get-by on a busted Lo Air Susp sensor problem. I have the new alarm module from Actia to put in this weekend (he took the coach to CO for a car rally). He will keep it. All you need to do is get a 1/4" o.d. Watts push tee (H.D. or Lowes or Ace), cut into the 1/4" o.d. plastic air line that stabs into the back of the lower idiot light cluster to the right of the dash gauges, and run a short 1/4" plastic line to a new fitting on the back of your new air gauge installed in the space to the right of the idiot lights (or wherever else it fits neatly). I pulled wire for the gauge light from the multi-post 12V source below the Vansco VMM in front; checked for a post that was switched on w/ignition key. That runs the light anytime the engine is running, but that's OK w/the owner (woulda been w/me also). The dimmer switch is a pulse width modulated gizmo to dim the LED dash switches/gauge lights, so that's a non starter for auto-dimming analog lights you might add to the dash cluster.
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Old 07-09-2010, 09:44 PM   #30
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EM-

Thanks for the reply. I had the same thought as you, but got the "highly unlikely" response based on past experience with these issues on trucks and RVs. They seemed to think it was more of an issue with moisture filling up the dessicant and then causing oil pull. I'm inclined to think it's a little of both - moisture which reduces the airflow and perhaps "pulls" engine oil past the compressor seals/rings when that condition occurs, and maybe a little blow-by, because I don't see a dirty engine from blowby.

I will change the cartridge again next year and see how it goes. If it's loaded with oil and not moisture, then we have a compressor issue of some sort which doesn't show itself in the standard test. The other theory I have is that this dessicant cartridge has had oil from an initial compressor issue before we bought the coach from the dealer in May of 2006, when it was new and had almost 1000 miles on the odometer. It's had this low air when cold issue as long as I can remember, and the spitter valve exhaust has always had an oil sheen.

I'll watch the spitter valve area and see if it starts to show oil again along the way between now and next year, and if it does, I'll have another discussion with Cummins Yakima about it.

BTW, it was very warm today (high 80's) in Tacoma and I moved to the coach to storage and noticed the spitter valve released within about 10 seconds of firing up the coach, which had set in the same spot for 3 days. That's the fastest I can ever remember.

Thanks for the info on the air gauge. I was thinking of doing about the same thing but going into the parking brake line. Going your way makes more sense, and I'll take a look at that. I can see getting light for the gauge from the 12V post in front of the passenger side panel, because it's switched. But then this problem occurs in the morning when cold, and it's always daylight when I leave, so I may just forget about lighting it so it's not on when dark. I usually don't need it then.

I'll think about this some more and maybe shake up a little Beefeater's tomorrow night when I have time to really contemplate it.
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Old 08-14-2010, 08:05 PM   #31
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We have had several episodes while driving in which the air pressure indicator drops and the warning light comes on. We pull the "strings" regularly but are wondering if our dryer is not working properly.
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Old 08-14-2010, 08:52 PM   #32
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For an 09 I'm guessing there is another problem, especially considering the visible nature of the onset. If the drier was going kaput, you would likely have some problem initially but after everything warms up it should act right as in the case of the OP. For an 09 your drier is practically new.
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Old 08-14-2010, 11:58 PM   #33
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EM & Jean & Leroy - seems to me there was a mention of the PTO takeoff maybe having an issue. I think if I remember correctly, the AC runs off this PTO place. But in reading the signature of the poster, he does not own an alpine, so he might think about going to the Tiffin Forum so see if other owners have ideas more common to his coach line.

However, that said, you can try the below checks and see if any of them help. The below is assuming (yeah I know) you have air bag suspension or something similar, and also have air chucks.

1. See if it bleeds down on any or more than one wheel after a short time, which I think, might be within one day.

2. When the air system is full, but the engine is not running, like start it and pump up everything full, let the compressor blow off one time, shut down the engine and then let it sit for a few minutes so you don’t hear a bunch of thermal cooling, etc, and all is quiet, see if you can hear air leaking out of any of the wheel areas, or around the compressor, and air dryer area.

3. Make sure none of the air chucks are stuck half way open and those valves which control them are closed off all the way. You might spray a little soapy water on the plumbing around those to see if you have some air leaks at one.

If those tests fail to show up any leaks, more in-depth checking will have to be done, which means someone is going to have to crawl under the thing. Please either support the coach at each wheel with some kind of wooden ramp (like drive the coach up on two of them for the front - then after that, do the same in the rear). I used some 4X10X18 inch wood blocks, which I faced with plywood 3/8" thick to keep it from splitting. I angle cut one end of each setup so I could drive up on them without creating a bad "jump effect". I keep them at home, unless we are heading out for an extended trip, in which case I might carry them along in case of emergencies. Let us know what you find out.

Additionally, you can also post the above on the Tiffin forum and get other answers from folks who own your brand of coach. Alpines are specific beasts and may not act like yours since ours normally don't have air brakes except for the emergency brake, and even that was not in all years of production.
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Old 12-09-2010, 03:38 PM   #34
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Figured it's time for a little update on this subject, since I started the thread. After replacing the air dryer cartridge in May, we had no issues with the "low air suspension" light, siren, and obvious lack of air pressure, when cold. But then it was also summer. I used the coach in November in Western Washington, and had no issues, but the air temperature was around 45-50 degrees each time I moved it.

On our trip down to Palm Springs for the winter at the end of November, we again had the problem at both overnight stays - same issue, get up in the morning to go, fire up the coach, wait until pressure builds up enough to pop the spitter valve (takes about 3 or 4 minutes when cold with air bags deflated), and begin a slow trip out of the RV park till the engine gets up to 140-150 degrees before getting on the freeway. Problem is once I put the transmission in "Drive" and begin moving, again the "low air suspension" display, warning horn, and lack of felt pressure in the parking brake occurs. We move a few feet, wait for pressure to build up, light and horn to go off, and move a few more feet until it happens again. Do this for about 15 minutes or so until the engine is up to 150 or 160 degrees and there's enough pressure to go for the rest of the day's drive with no problem. Next morning, repeat the process all over again.

Both of these mornings the air temperature was around 35 to 40 degrees. Upon arriving in Palm Springs, we tested it the next morning, and had the same issue, though it lasted only for a minute or so, but the temperature was near 50 degrees. Based on advice by Gary Arnold, we also installed an $8 air pressure gauge from Lowe's at the air suspension dump valve, so we could monitor pressure when we cranked it up and moved it.

Using this gauge, we found the air pressure builds to 120 psi, but when the parking brake is moved on or off, it drops 20 - 30 lbs each time it's activated -- do it twice in row and it will drop to around 80 psi. So if we move it, we'll get the warning unless it has 100 psi or so of pressure built up, and this occurs slowly when it's cold outside and the engine's not warm.

Decided to take the coach to Colton Truck Terminal (4th company in 2 years to work on this issue) yesterday to have them look at the compressor since it's not pumping up enough air as fast as it should when everything's cold. At CTT, Air temperature was 59 degrees, dumped airbags, pumped it up in a couple minutes or so,and of course no issue. At CTT they spent some real quality time with a tech that really knows air systems looking at the system while I was watching, and determined that there's nothing wrong with it at 50 degrees or so, with a warm engine from driving it there. Took the governor off the air compressor and tore it apart; looked fine (this is supposedly one of the main causes of this problem). Same thing with purge valve -- no issues. Decided to replace both of these parts with new ones anyway since they are cheap parts. We fired up the coach with the air disconnected from the governor and felt and measured the air flow directly from the compressor, and it's fine. There was no oil in the line from the compressor to the air dryer, nor beyond it up to the air tank, which we suspected earlier might be the problem. Examined for leaks in the system and there are none; the coach will hold 120 psi of air when shut down for 1/2 hour or more, when the air bags are inflated. Technician put shop air directly into the compressor to see if he could make the unloaders on the compressor work as they're supposed to, and they do.

So the conclusion of all this work is to 1)try it some more on cold mornings here in PS in January-February and see if we can duplicate the problem. 2)if the problem persists,the tech from CTT, who lives nearby will take the head off the compressor and see if the unloaders are sticking when cold. 3)if that's not the issue, Cummins said they will replace the compressor, because for whatever reason it's not pumping enough air when cold and the rest of the system is working fine.

Several of you have asked me about how this issue was going, so I thought I would give you the full reply, in case others are having this issue.
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Old 12-09-2010, 03:44 PM   #35
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Slack adjusters too loose on parking brake? Which is also the brakes. Also, if you loose enough air pressure in the rear, your parking brake would start to lock up wouldn't it?

You did check and see if the air tanks aren't full of water? (Blow them down)
Did they check the cutout pressure of the compressor? Might be set to low
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Old 12-09-2010, 03:59 PM   #36
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AK.

We don't have air brakes on Alpines, only air suspension. Parking brake system was checked and it's fine. Air pressure doesn't go below 60 lbs, hence parking brake doesn't lock up; it just doesn't have a lot of pressure at the switch, when it's cold.

There's only one air tank because there's no air brake system. The tank is dry

Yes they checked the cutout pressure of the compressor; that's one of the functions of the governor and it's set to 125 psi before it pops the spitter valve.
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Old 12-09-2010, 04:41 PM   #37
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Then how do you loose air pressure when you release the brakes?
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Old 12-09-2010, 07:38 PM   #38
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Did you check the Haldex parking brake actuator for leaks? A couple have gone bad & owners replaced them. I'd think you'd hear a leak there that would be this serious, but maybe not.
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Old 12-09-2010, 09:52 PM   #39
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EMike,

Yes, we checked the parking brake. And there's no leaks. It was one of the places I thought about as well, but thanks for suggesting it. Like I was saying earlier, we can't find any leaks anywhere in the system. Plus it holds air when parked, as shown on the gauge, but loses it fast when cold and when I move it, even before the parking brake is applied. When it's warm, the parking brake works fine and can be cycled off and on 2-3 times quickly and still doesn't lose more than 20 lbs air, so we can move on without the warning indicators.

AK, I lose air when I release the parking brake, cold or warm, but a lot more when it's cold, and it builds up more slowly when it's cold. Because the air pressure is low, the switch feels "soft" when I immediately push it back on.
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Old 01-04-2011, 11:21 PM   #40
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Another piece of follow up on this issue --

I have had the chance now to test this issue on a cool day -- 40 degrees - in Palm Springs, and learned some additional things to add to the previous discussion. The air gauge I added to the suspension air dump valve has taught me a lot.

1) When it's cold it takes longer to build up the air pressure to 120 psi, when the spitter valve exhausts the excess air pressure. With the air dumped, it takes a while to fill the air bags before it can begin building up pressure.

2) When I release the parking brake to move the coach the pressure immediately drops to 60 psi, which, when I move the coach gives me the low air suspension warning and the soft parking brake "feel" when I put the coach in neutral and reapply the brake.

3) It takes somewhere in the range of 70 to 80 psi of pressure to kick the low air suspension warning off, and begin travel.

3) Since I have the parking brake applied and the tranny in neutral, I put it in drive and release the parking brake, which immediately causes the air pressure to drop to 60 psi or so, and give me the warning light again.

4) In the past I have gone through this cycle of putting the brake on to build up the air pressure and then releasing it, moving, and having the warning come on again. I go through this cycle over and over again for 10 to 15 minutes until the engine gets warm and then I'm fine for the rest of the day. I notice when the engine gets warm and I release the brake, it drops to about 70 psi and builds up rapidly back to 120 psi. This is enough to keep the low air warning alarm from coming back up. If I keep the brake off, the air pressure stays up with no problem.

5) Holding the engine to 1000 or 1100 rpm fast idle via the throttle (ours does not have the fast idle/cruise control feature) to get it to warm up faster doesn't appear to cause it to build air pressure significantly faster when it's cold. The engine has to warm first.

So, my conclusion at this point is the air compressor is the culprit. Either the piston in the compressor and its seals are too sloppy when cold and need to warm up to generate full pressure or the piston shrinks more when cold than the case around it (perhaps a different alloy, or the rings/seals are damaged/worn). If it were a parking brake problem I would think the actuator would leak air all the time, even when warm. We can't find any leaks, the actuator works, and once the engine's warm there's no problem holding air pressure at 120 psi.

Because the parking brake takes so much air pressure to actuate, it appears to me reapplying it as I have been doing is not a good idea when it's cold. Better to leave it off, once I take it off, and use the foot brake to let it build up air. This should get me around this issue in the near term.

I plan to change the compressor in April when I'm home, and have already got Cummins to agree to do so on the remaining engine warranty. There's basically nothing left in the air system to replace.
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Old 01-05-2011, 05:12 PM   #41
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OldForester,

You state in your #5 item, "...ours does not have the fast idle/cruise control feature..." I'm surprised at this, since my 2006 Alpine Coach Limited 36FDTS DOES have this feature. What's different?

Also, you state, "So, my conclusion at this point is the air compressor is the culprit." To me, this conclusion doesn't explain this other statement from you, "2) When I release the parking brake to move the coach the pressure immediately drops to 60 psi..."

Since you state that the compressor does get the pressure to 120 psi, why does the pressure drop immediately to 60 psi when you release the parking brake? Is that immediate drop to 60 psi the fault of the compressor? Are you suggesting that the compressor should get the pressure above 120 psi? On my coach, I've put a pressure gauge on the "AUX Air Chuck", which never gets above 120 psi.

It seems to me that when you release the parking brake, then whatever is causing the immediate drop to 60 psi is the real culprit. Is that the compressor?
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Old 01-05-2011, 10:39 PM   #42
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Dale,

I've had a couple different Alpine owners show me how to use the fast idle feature on their coaches and it doesn't work on ours. So I'm having Cummins Yakima look at it when I take it in for annual service in April. Wayne R has a similar coach and he also says his has never worked. We tried to program it at Colton Truck Terminal while we talked to Cummins Yakima, and we couldn't find anything wrong with the programming, so it must be something else.

On #2, I'm not suggesting the air pressure get above 120 psi. It goes there and stays around there, and everything works fine as long as the engine is warm. I'm saying that when it's cold, the air pressure drops 60 psi when I release the parking brake, and it takes a significant time to build back up to 70 to 80 psi and get rid of the alarm. When the engine's warm, the parking brake still causes it to drop from 120 psi to 60 psi or so, but it builds back very rapidly to 70 to 80 psi, and then on to 120 psi and the alarm doesn't go on. Also, the "feel" in the parking brake on/off is firm/solid, not "spongy".

If you recycle the parking brake off/on 2 or 3 times rapidly in succession I think you will find it takes a lot of air pressure to apply the brake and it takes a little bit of time to build it back. But when I do that and the engine is warm it builds back quickly. Cold, in 35-40 degree weather I need to wait for significant thaw to get it going.

So, that's the issue, and along with the fact we've replaced about every other component in the system short of the air bags and the air lines, and checked for leaks multiple times makes me think it's the compressor. The brake seems to function just fine, and shows no sign of leaking. Also, the fact my air dryer cartridge loaded up with oil over the last 4 years makes me think the oil is somehow getting past the seals/rings on the air compressor piston when it's cold.

Just been working on this issue for 4 years, trying everything, having 4 different repair companies look at it, at least a dozen different individuals give me input on it, and getting tired of it, contributes a little bit to my view it's time to replace the compressor.

Thanks for your thoughts; let me know if you have other questions about it. All ideas are welcome.
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