Why would Air Be Blowing off from the outside

[Team Wilhelm]

I have a Cummins 350 on a 08 Forest River Berkshire. While driving it lately on occasion this year down the hwy I will hear inside the coach the air system blowing off from outside. It will blow about 10 times in a row every 5 seconds or so apart. Sounds like if someone was pressing the air brake pedal? The gauges read ok etc and brakes work fine. Anyone got any idea why it would start doing this ? I have 25K on the unit and this is the first time I’ve heard it. I had a second coach following me last week and they could hear it from following behind me. Thanks…Ron

[tmmar]

Did you get any resolution to your problem? Something similar just began with my coach, also an '08. I noticed that sometimes, when I start off from a red light, I will hear air blow off several times. I usually only hear it when I start to pull away after a stop at a red light.

[lindy]

By any chance was it a very humid day? If so it was your air dryer dumping moisture that built up in the air system because of the damp air.

[jimh]

do u by any chance have a turbo w/intercooler?
there is another post on here abt intercooler hose failure.

[tmmar]

Originally Posted by lindy

By any chance was it a very humid day? If so it was your air dryer dumping moisture that built up in the air system because of the damp air.

It was, in fact, very humid. I am travelling this week and it is supposed to be drier so I will see if it makes a difference. I am hoping that it is because of the damp weather and nothing more serious. The Cummins is turbo charged but not sure about the intercooler.
Thanks.

[wnytaxman]

I've noticed the air discharge when the rig goes from 5th to 6th. If you've had a lot of short downshifts, that may be what you heard.

[tmmar]

Ed,
This was on a local road with traffic lights and many stops and starts. Transmission never had a chance to shift beyond of 3rd or 4th.
Thanks.

[Team Wilhelm]

Originally Posted by Team Wilhelm

I have a Cummins 350 on a 08 Forest River Berkshire. While driving it lately on occasion this year down the hwy I will hear inside the coach the air system blowing off from outside. It will blow about 10 times in a row every 5 seconds or so apart. Sounds like if someone was pressing the air brake pedal? The gauges read ok etc and brakes work fine. Anyone got any idea why it would start doing this ? I have 25K on the unit and this is the first time I’ve heard it. I had a second coach following me last week and they could hear it from following behind me. Thanks…Ron

Funny you ask. After alot of research before I took it to a dealer for $$$$ I just ordered on Friday a little relief valve that goes on the Haldex air dryer my unit uses. I was told on 2008 they used a 175 psi vlave here and it should be a 200 psi. As valve gets worn it starts to blow off easier. This is only what I'm told by a local freightliner dealer. The valve is $17.00 and easy to change (it's as bottom is the air dryer on mine and on the driver side of the dryer at the very bottom.) It's about the size of your thumb. So for that price and my dealers advice I'm changing mine. Were hoping this is what the air popping off is. The part # is HDX KN31529. I should have it by this Wed. Sounds Tumar like it's the same thing. My was releasing air at about 14-20 times steady and varied when it did it but it was not normal. Hope this helps.

...Ron

[Team Wilhelm]

Funny you ask. After alot of research before I took it to a dealer for $$$$ I just ordered on Friday a little relief valve that goes on the Haldex air dryer my unit uses. I was told on 2008 they used a 175 psi vlave here and it should be a 200 psi. As valve gets worn it starts to blow off easier. This is only what I'm told by a local freightliner dealer. The valve is $17.00 and easy to change (it's as bottom is the air dryer on mine and on the driver side of the dryer at the very bottom.) It's about the size of your thumb. So for that price and my dealers advice I'm changing mine. Were hoping this is what the air popping off is. The part # is HDX KN31529. I should have it by this Wed. Sounds Tumar like it's the same thing. My was releasing air at about 14-20 times steady and varied when it did it but it was not normal. Hope this helps.

...Ron

[Team Wilhelm]

Originally Posted by tmmar

Ed,
This was on a local road with traffic lights and many stops and starts. Transmission never had a chance to shift beyond of 3rd or 4th.
Thanks.

My does it a low speeds also but also going down the highway and seems after you applied brakes etc

[Team Wilhelm]

Funny you ask. After alot of research before I took it to a dealer for $$$$ I just ordered on Friday a little relief valve that goes on the Haldex air dryer my unit uses. I was told on 2008 they used a 175 psi vlave here and it should be a 200 psi. As valve gets worn it starts to blow off easier. This is only what I'm told by a local freightliner dealer. The valve is $17.00 and easy to change (it's as bottom is the air dryer on mine and on the driver side of the dryer at the very bottom.) It's about the size of your thumb. So for that price and my dealers advice I'm changing mine. Were hoping this is what the air popping off is. The part # is HDX KN31529. I should have it by this Wed. Sounds Tumar like it's the same thing. My was releasing air at about 14-20 times steady and varied when it did it but it was not normal. Hope this helps.

...Ron

(I might of answered this a couple of times - sorry)

[Bigglesdaf]

This very important!! You MUST remember to empty the air tanks on a weekly basis when being used as water can build up in the air tanks reducing the air capacity this can lead to loss of air pressure if left unattended especially in humid climate. A symptom of this is the Air relief valve blowing off more frequently than is normal.
Any big rig truck driver will tell you this a normal weekly routine on their rigs!!