Strange Sound Emanating from My Coach

For two months I've noticed a sound as I sleep at night. It sounds like a muffled jake brake and it cycles over and over from high pitch to low. Since I've been in an RV park across from the Long Beach Ports, I actually thought it may have been the trucks that service this area 24 hours a day. But, I moved the coach this weekend to a quite locations and guess what, I woke at 3:00 AM thinking I had brought the trucks with me. I turned off every breaker in the coach and the sound did not go away. I was plugged into 50 amp power and the inverters were on but I couldn't tell if they were the cause. Any ideas to keep me from going completely nuts?

Richard Barnes

some tank(water,black,gray) level sensors have air pumps that run every so often,I think that they sound like your description,they usually only run 10-15 seconds every 10 minutes or so.

Well, I was thinking aux air comp until you said you shut everything off?

Is your coach up on the bags when overnighting, or is it down on the stops. If you keep it raised, where is it in the morning? The sound could be that last evacuation of air as the pressure gets low and the bus sinks to the stops.

Just guessing.

JIM

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Originally Posted by jack14r

some tank(water,black,gray) level sensors have air pumps that run every so often,I think that they sound like your description,they usually only run 10-15 seconds every 10 minutes or so.

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This is continuous. It cycles over and over. It is not so loud as to be annoying when the TV is on or when the AC units are blowing but in the still of the night or day for that matter, it never stops. It is a mystery!

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Originally Posted by JIM CHALOUPKA

Well, I was thinking aux air comp until you said you shut everything off?

Is your coach up on the bags when overnighting, or is it down on the stops. If you keep it raised, where is it in the morning? The sound could be that last evacuation of air as the pressure gets low and the bus sinks to the stops.

Just guessing.

JIM

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Jim it is on the bags at all times. This is a real mystery and I'm sure it will drive me absolutely nuts before I find it.

Richard,

Putting your conversion and year in your signature would help you with answers. I don't have a clue what you have.;)

It would help if we knew the year and converter of the coach.

I think all of our coaches have "key off" devices that serve numerous purposes and any advice I give as a Liberty owner may be of no value to the owner of another conversion.

I agree with Jack, except I can't hear mine in the coach, but I can hear them when I am working next to the coach in my garage.

What I hear in my coach are the inverter cooling fans and the auxiliary cooliong fans remote from the inverters. The remote fans run continuously controlled by a switch, the internal inverter fans run via a thermostatic control in the inverters.

But you could also be hearing the satellite searching for a signal.

I agree with Jack and Jon.

I think it is your holding tank sensor system. I used to cut mine off at night so I would not hear it gently hum whilst it blew the air out of the tube to refresh.

It was not something you would notice unless in an extremely quite time and place.

No comment

My vote is aux air compressor. The one we had in the Royale was noisy and had a high / low pitch as it neared shutoff. I can barely hear the one in the Marathon unless everything is dead quiet and I am near the generator bay.

Truk4U Tom has these same intermittant noise problems. Maybe he will chime in.........

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Originally Posted by truk4u

Richard,

Putting your conversion and year in your signature would help you with answers. I don't have a clue what you have.;)

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1998 Liberty XL
Thanks, Richard

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Originally Posted by truk4u

Richard,

Putting your conversion and year in your signature would help you with answers. I don't have a clue what you have.;)

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Tom,

I have a 98 Liberty XL
Thanks,
Richard

Richard,

Could it possibily be one of the Inverter fans?? Don't know about Liberties, but in Marathons of our vintage, the fans are hardwired and shutting off all breakers wouldn't silence them. One could be going bad.:(

Richard,

Now I can get specific. If the noise is under the dish, see if the satellite is looking for a signal. That thing makes lots of noises if it loses a signal due to trees, heavy clouds, or just because it is acting up.

On both sides of the last bay you will hear the timy pumps that Jack and Roger mentioned. They cycle periodically. If you think that is what is doing it, turn off the switches at the level displays over the front windows in the TV control box.

If it is the aux air compressor you will hear that coming from beneath the floor somewhere under where the floor slide is. The bottom LH switch in the electric panel should kill that noise.

If it is the inverter fans, making lots of noise is a bad thing. My inverters are under the bed. Yours may be in the electric compartment. Regardless of where they are, if they are making the noise that needs to be takne care of pronto. A noisy inverter fan is one that is failing, and if it does quit heat can damage the inverter.

Other things that make noise in my coach are the refrigerator. It has a condensing coil fan located in the rear bottom near the compressor. If that is the noise that needs to be replaced also or your refrig is done working.

There are a lot of other fans and noise makers but they are assocated with stuff like the Webasto. The Webasto sounds like a jet plane when it lights off. The circulating pump sounds like a whine, and the various heat exchangers throughout the coach just make a lot of noise.

There is a circulating pump in the Webasto system that runs randomly for a short duration. Very quiet though, but yours might be going bad. After first getting the bus the sound would bother me. Now that I am used to it, I rarely notice it.

I thought you had a Liberty. You just sounded like a Liberty kind a guy.;)

JIM

Jim,

I know of no reason why the Webasto pump runs randomly, nor would I describe it as quiet.

Are you sure you are not confusing that with the Headhunter water level mini compressors?

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Originally Posted by Richard Barnes

For two months I've noticed a sound as I sleep at night. It sounds like a muffled jake brake and it cycles over and over from high pitch to low. <snip> Any ideas to keep me from going completely nuts?

Richard Barnes

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I had a similar problem once, but I took some Bean-o and it fixed me right up! :p

Mikey: You are fitting in with Jdub POG group for sure.

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Originally Posted by rfoster

Mikey: You are fitting in with Jdub POG group for sure.

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Rut-roh! :eek:

Richard wrote: I turned off every breaker in the coach and the sound did not go away. I was plugged into 50 amp power and the inverters were on but I couldn't tell if they were the cause. Any ideas to keep me from going completely nuts?

If Richard has cut off all breakers to the converter side of the bus, then what besides the inverters themselves could be making any noise that is converter related?

He appears to have a 2001/2003 Prevost XLII BY ??. But if he has no AC on in the bus then could it be Prevost related, maybe the air compressor, High pitch to low makes sense the Jake Brake sound leaves me puzzled. I also hate noises at night.

Richard wrote: It sounds like a muffled jake brake and it cycles over and over from high pitch to low.

I'm gonna change my answer; It sounds like the sat dish looking for a signal. When ours does that, I just let it lock on then turn the dish off and it works okay. But it makes an annoying, grinding sound and you can generally only hear it right under the dish (which is the bedroom for us).

MT - The correct response to the King is - Bite Me.

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Originally Posted by Jon Wehrenberg

Jim,

I know of no reason why the Webasto pump runs randomly, nor would I describe it as quiet.

Are you sure you are not confusing that with the Headhunter water level mini compressors?

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Jon,
I suppose I could be confused about that.

I didn't know about the mini compressors until today.
Where would they be located? How can I be sure they are working?
What voltage do they run on?

The sound I hear is in the area of the driver side tag and it comes and goes randomly and is not very loud. I associated it with the Webasto, but it runs at times when the Webasto is turned off.

Jim,

Open the water/sewer bay on the driver side and you will probably see a "black box" that is attached to the waste tank. A small air line will run from it into the top of the tank.

There should be a small pin switch on the top, which you can depress to manually start the small pump. It will cycle and then shut off.

This should tell you if it's the sound you are hearing.

Thanks Paul, I'll try that.

JIM

Ok, On my Liberty, the weird noises I tracked down:
1. On Port side bay #2. the small axial vent fan was slowing and stopping,
making a low hum tone.
2. On starboard bay #2, behind small refer, same type of axial fan going bad.
3. Port side, Bay #4. the level monitor for black/grey tank. humming noise.
4. Canopy Air compressor, intermittant start/stop. Located in middle of Coach, with Coach batteries and Cruiseaire heat pumps.
5. Ice maker, Culligan filters, cycling of water pump processing water thru filter membrane. low hum.
6. Wife Snoring
7. Dog snoring

Gary, I like your presentation. You get an " A "!:

:DJIM

Jim
Do you have auto start on your genset? If so, turn it off at the dash and see if the noise still exists.
I had a similar noise and traced it to the module that controls the auto start.

Gary,

I had a similar issue in my plane. I was flying along and noticed an unusual noise which is never good but especially bad in an airplane.

I start turning things off, recycling stuff and trying desperately to find the source of the noise. I pull my noise cancelling headset off and turn my head trying to get a bearing when I notice that my wife is in the backseat catching flies and snoring like a logger.

Twenty minutes of hand wringing for nothing. Now when an errant noise pops up, I always locate her and assess the situation from there.

Of course with the Trukman in the plane, you always have to look for this;

http://dangim50.com/Pages/Photos/abbey_9588.jpg

Thanks for the idea Pete, but I have yet to use auto start on the generator.

JIM

Jdub's daughter fell asleep next to yours truly because of the co2 inhaled by having his doctor killer tucked up so tight to the lead plane I could see the other pilots nose hairs!

So Richard, What was the " Jake Brake " noise ?

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Originally Posted by JIM KELLER

So Richard, What was the " Jake Brake " noise ?

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Jim,

I'm still looking and listening. The sound is still there but I've eliminated the satellite tracking, and webasto as the cause. I'll keep looking and let you know as soon as I find it or in case I go stark raving mad from the annoying sound, the lovely Mrs. Barnes will post the answer.

RB

Richard, just wondering, does anyone but you hear the sound?? :rolleyes:

JIM :D:D

Richard, let us know if you use an ice maker, and turn it off for a while to rule it out, if you do.

On my bus, similar to yours, there are cooling fans for the electricals down in the bays. Somewhere behind the scenes and out of sight in bay two. They run all the time. Maybe they are going bad.

Have you checked for anything by looking from the outside of the bus, that is, under it or in the bays. Is it louder there or not even heard.

Early on you said you turned off all the breaker switches. I took that to mean those on the interior panel.

Have you tried turning off the inverters themselves after turning off all the circuit breakers?

If you turn off the engine and house batteries at their switches does the sound go away. If so turn them on one at a time and listen for the sound to come back.

:D I see from your profile that you are in Labor Relations, have you ruled out a bomb?:D

JIM

I skimmed through the 4 pages of replies. Not sure if anyone suggested the air pump for the toilet but mine was cycling like that except I'm not sure if I would compare it to a jake sound. It slows down and the sound changes and finally stops when it reaches pressure.

There is another thread I had on this and how I remedied it with the right check valve in line instead of replacement of the pump which was getting worn and letting air leak back out. With the check valve, it NEVER looses air, leaks and runs every so often anymore. If you want, email me and I'll find the old link, or I still have photos in my computer that I can email you direct if you want to check this out.

But as someone suggested, you might want to locate the suspect, open the bay and kick back and see if you can catch the noise to see if that's it. On my system, it has a pressure gauge and you can make a note of your pressure, return 10 minutes later and see if it's dropped and get a clue.

Yes, the lovely Mrs. Barnes hears the same noise. This weekend I intend to isolate this noise. I'll let you guys know what I find.

RB

Okay guys, I isolated the noise and it is the fresh water tank sentry. Any ideas on how to repair this? Any help appreciated.

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Originally Posted by JIM KELLER

So Richard, What was the " Jake Brake " noise ?

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Jim,

It is the fresh water tank sentry. Any ideas on how to repair?

These tank sensors normally do make some noise as they do their job. Your noise could easily be "normal" and not necessarily in need of repair.

If it's bothersome during the night, try just turning the sensor off.

Just remember to turn it back on later....

The noise as Paul points out is normal. The lack of noise is the abnormal condition.

I think this was pointed out earlier, but if not it is a tiny compressor in the unit that purges the sensor tube with air. Then the pressure from the column of water in the holding tanks is measured and used to light the level indicator lights.

If the sound is annoying turn off your water and holding tank sensor system.

Think of it like you do the engine. The engine makes noise when it is working.