Strange Horn in Heat

[jasonruyle]

This has been a problem for a year. When it gets hot out (85-90+) and my car is sitting out, when I start my car I get a horrible horn noise from the engine area. My RPM usually will jump up, the noise gets bad, if the RPM drops to 700 or less the noise goes away.

If I step on my accelerator, the horn goes back on. I can then start driving and the horn goes away with added acceleration. If I get to a stop, the horn may continue at a very loud noise, but sometimes my rpm will drop, the horn will stop, and my car will almost feel like its going to stall. At this point, the horn noise might go away.

Usually, the horn noise will go away after 10 minutes of driving. In fact, if I drive it, stop and don't turn off the car, the horn will not start again. But, if I turn the car off, the horn will start right back up. This issue only happens in the summer time when its hot out. I sometimes have to drive with my brakes and accelortor because its so loud. People think I'm actually honking at them, but its not a horn noise. Its a HOOAAAA!!! noise.

Anyone see this issue? I've replaced my alternator, water pump, belts. I'm not a mechanic, but had a mechanic help me with the replacement of these things. It still is happening. My explorer has 170k miles.

 

[Dan Whitaker]

Sounds live a vacuum leak. I would check at the brake booster first since it goes away when you apply the brakes.

 

[Blee1099]

Does it sound like a train whistle? If so its your IAC, try cleaning it.

 

[jasonruyle]

The noise goes away when I put on the accelerator, but I have to drive with my brakes on just to keep from speeding. Around 800 to 2000 rpm is where the horn noise goes off, its always within the first startup to 10-20 minutes of driving. Its constant for that time, and then goes away.

It's not a whisle noise, its a deeper noise, almost like the sound of an actual horn. The noise seems to be coming from the actual motor, could it be a bearing? hmmm...

 

[Blee1099]

If sounds like this, http://homepage.mac.com/dogfriend/Explorer/iMovieTheater14.html then its the IAC..

 

[Brett F.]

That is insane. Great post Blee. Now I will know what it is when it does go.

Thanks