Fog Horn like sound from front of vehicle

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SWWAFordGuy

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I'm getting a fog or air horn like sound from my front end. However, this has only happened 3 times in the last 2.5 months. From what I find online, its supposedly common for brakes. But, if the brakes are having issues, wouldn't this noise be more constant like all the time and would I notice any decrease in brake performance?

There's no pattern to when this noise occurs. Twice it was as I exiting the freeway and the last time was when I made a short trip to the store. None of these times were there any sharp turns at high or low speed so that might, stress might, eliminate a steering issue.

I had the brake lines (20years old) and fluid replaced and the brakes on all 4 wheels inspected. No issues. Everything is where it should be and nothing is showing unusual wear.

Any one have any idea what could cause this?

1997 Expedition with 4.6, 4wd.
 

Punisher

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In colder weather my mom's Ford Contour has what is called "moosing". It is a strange noise from under the hood that sounds like a moose or loud fog horn at idle and when you hit the gas it gets louder. From what I have read it could be caused by the idle/air control valve and some say replacing it fixes their problem. I basically do not worry about it as it will go away usually once warmed up.

Not sure if this is what you are experiencing but figured I would throw this out there. Just search google for ford contour moosing or fog horn noise.
 
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SWWAFordGuy

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Update on the noise. Had it in the shop today and my mechanic put the brake system under vacuum in an attempt to duplicate and/or troubleshoot if the issue was coming from the vacuum booster. Nothing happened. No noise, no sign that it was a brake related issue. And he checked the IAC by using both a diagnostic tool and visually removing, cleaning and re-installing it. So far, nothing has happened but then again, this seems to have no discernible pattern. At least it wasn't a vacuum leak.

The times this noise occurred has not been cold or the engine cold. All the instances occurred after the engine has reached proper operating temp and it has never happened with a cold start.
 

Korution661

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In colder weather my mom's Ford Contour has what is called "moosing". It is a strange noise from under the hood that sounds like a moose or loud fog horn at idle and when you hit the gas it gets louder. From what I have read it could be caused by the idle/air control valve and some say replacing it fixes their problem. I basically do not worry about it as it will go away usually once warmed up.

Not sure if this is what you are experiencing but figured I would throw this out there. Just search google for ford contour moosing or fog horn noise.


This is an issue I have had in cold weather too. Does not happen often but every once in a while it will, but like he says onces warmed up within 2 mins or giving gas it goes away.
 
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SWWAFordGuy

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Update #2: Fog horn/moosing noise happened again, in fact, 3 times within an hour, each time as I was slowing down. Took it back to the mechanic and we both decided that replacing the IAC valve was worth looking into. Strange thing, the replacement IAC for the 4.6, as you look at it, has the nozzle connector angled downward at about a 45 degree angle. That won't allow the hose connection to be made. Had it install the 5.0 IAC as the connector nozzle wasn't at that angle. Good news though, the moosing went totally away. Thanks to all who pointed me in the direction of the IAC being the culprit.
 

seawalkersee

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Sorry about the late reply on this, but yes, 90% of the time, it is the IAB. The noise happens because the spring that controls the valve is getting weak or is broken. When it is broken, the noise is almost all the time at idle. A LOT of aftermarket IABs do not have a strong enough spring to continue to do the work of the IAB and will "Moose" all the time. Usually, if you pull the plug on the IAB, the car will die. With a weak spring, it may still run at a lower RPM.

The other cause you can get is because of a vacuum leak on a large hose. Usually when they do that, you can hear it go away and make the sucking noise when you give it gas.

SWS
 

Randy D

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Does your vehicle have the auto leveling ? The compressor will come on at random times to pump up rear air bags and level the vehicle.
 
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