Hissing sound

[merle&louise]

I have recently noticed a hissing sound when I accelerate and ascend an incline on a bridge or even on flat ground. If there is a concrete wall (roads under construction) and I push the accelerator to the floor, as the speed increases I hear a loud hissing sound. As soon as release the accelerator, the hissing sound stops! I can't pinpoint the location of the sound.

Does anybody have a clue? Could it be my muffler? I looked at the muffler and it does need to be changed; it has a few holes in it and is rusting out.

The only air in my system would be in the suspension system; so why would the hissing sound increase when the engine rpms increase?

Maybe the turbo? The boost gauge pegs out at the max when I push the accelerator to the floor. So I am not losing boost.

Should just buy a new Liberty or try to fix my Newell?

[m stuller]

Tuga: I have had this happen to me on occasions and found it is coming from the speakers. Once i turn off all the electronics or radio that the sound volume is truned down all the way the sound goes away. Try this as the way you described the hissing sound is exactly the same way that i would describe what was happening to me.

The problem with going out and buying a new coach is that you will have the same problem!

Matt

[Jerry Winchester]

Tuga,

I recently had the same problem and I noticed it because I drove near a barrier like you described with the window open.

Upon further inspection, I had a leak on the pipe that connects the exhaust manifold to the turbocharger. It was the hissing of the leak that caught my attention. An exhaust leak in several parts of the system would sound similar.

Or as Matt stated, I have had many engine / coach problems that turned out to be (A) The girls had a movie turned up too loud in the back (B) The girls had the Nintendo DS cranked up behind me and I couldn't see them (C) The girls had the stereo or some other electronic device running that I couldn't see but could hear (D) My wife was snoring (E) Some moron pulled up next to me in a snapperhead car with a fart can muffler and a 1000 watts of bass.

[merle&louise]

Matt, Thanks for the advice. I checked to see if the surround sound or DVD player was on; all systems off.

JDUB, The exhaust manifold connection to the turbo seems like a pretty good guess. I will begin my search there.

Thanks guys for the quick replies, I'll update as the problem gets closer to being solved.

[JIM CHALOUPKA]

Tuga, My vote is as well for the exhaust. When you are close to the wall you hear the sound upon acceleration and not when backing off. You say you have holes in the system. They leak more under heavy acceleration. Entertainment center sound would not be linked to the throttle.

A periodic drive through areas with walls close by at speed is a good way to notice maintenance items that require closer scrutiny. Sounds that are normally thrown out into environmental space and lost are thrown back at you to be audible red flags!

[Jon Wehrenberg]

Tuga,

I don't know how Newell set your exhaust up, but the pipe from our turbo to the muffler has a life of about 10 to 15 years. On our coaches it is especially hard to see all parts of it, but if it or the muffler begins to develop leaks that is what you might hear.

It also might just be the turbocharger and you may have only become aware of it making a noise.

[merle&louise]

Jon,

I have an appointment at Newell for July 23 to have the muffler replaced. I may just wait until that time and road test it after the new muffler is installed to see if the hissing sound still persists. That seems like the best way to attack the problem at this time. I will, however, visually inspect the exhaust manifold connection to the turbo like JDUB suggested.

Jim,

Glad to hear that you concur with Jon on the exhaust being the culprit. Now that I think about it, I remember back when my '93 Newell muffler started rusting out I noticed a pinging sound when accelerating next to a concrete barrier wall.

The more I discuss it, the more convinced I am that the muffler is the problem. Boy am I glad that I don't have to buy a new Liberty!

Thanks guys, as usual the POGGERS come thru.

[JIM CHALOUPKA]

Tuga, You don't have to buy a New Liberty! A used one would be just fine.

After thinking on your hissing sound, could it be that you used a little Snake Oil the last time you had to add engine oil?

[Larry W]

Just a thought. Before being consumed by MPD I have a similar noise in my glass pusher. Was about to think it would never be found. It was the mic on the backup camera volume control turned way up. Turned it off and no noise.
Larry W
2000 Royale

[rmboies]

Tuga,

When we were caravaning to Kerrville and you and Karen were in front of us, I often heard a roar/hiss noise coming from your coach. It was not constant it would come and go..... Bob told me it was just your jake break but maybe not? If not, then sorry I didn't mention it!! I do like your idea of jumping into a Prevost though, this would be the perfect excuse