Train whistle blows when braking

[mackeroni]

I realize that diagnosing sounds that are not heard, but only described is a real crap shoot, but here goes.

Sometimes, within the first five miles of driving, I can hear a slight multi-toned sound, something like a train whistle, when I apply the brakes. It seems to be coming from under the hood, not from the brakes themselves. It is not very loud, just barely detectable and not recordable. As soon as things warm up, it goes away. The sound is not troublesome at all. I just don't want to miss the early signs of a repair that will be needed to keep my brakes working properly.

I examined my front brake rotors and calipers and do not see anything unusual. Is it possible that the sound is associated with the operation of the power brake booster before it is up to operating temperature? I cannot duplicate the sound while sitting in the garage, only when moving... and only faintly. Any other ideas?

Peace... Mack

[Gassed135]

Originally Posted by mackeroni

I realize that diagnosing sounds that are not heard, but only described is a real crap shoot, but here goes.

Sometimes, within the first five miles of driving, I can hear a slight multi-toned sound, something like a train whistle, when I apply the brakes. It seems to be coming from under the hood, not from the brakes themselves. It is not very loud, just barely detectable and not recordable. As soon as things warm up, it goes away. The sound is not troublesome at all. I just don't want to miss the early signs of a repair that will be needed to keep my brakes working properly.

I examined my front brake rotors and calipers and do not see anything unusual. Is it possible that the sound is associated with the operation of the power brake booster before it is up to operating temperature? I cannot duplicate the sound while sitting in the garage, only when moving... and only faintly. Any other ideas?

Peace... Mack

My 2012 135 is also making a noise when braking, but comes from the hood. The way i would describe it is similar to the sound a dolphin makes. Weird.

[mackeroni]

Originally Posted by Gassed135

My 2012 135 is also making a noise when braking, but comes from the hood. The way i would describe it is similar to the sound a dolphin makes. Weird.

Yeah, I saw your post just after I hit <ENTER> on mine. How about that? Dolphins and train whistles... Flipper and Casey Jones. Could they be related? Hope someone can tell.

Peace... Mack

[Dackelone]

Did you have ANY work done on the car recently ?

I would look at the hose clamps - on the vacuum hose leading to the brake booster. Also check for any standing water down in the sub-fire wall under the brake booster area. Often times old leaves and crap clogged up the drain hole(s) and allow water to backup around the brake booster.

[olds350]

This really sounds like a brake booster issue. Check any hoses going to the booster itself, it's vacuum driven to provide power assist to the brakes