'99 Grand Cherokee Limited - high pitched whistle

I need some assistance. About a month ago, my JGC began to make a high pitched whistling sound. At first, it was intermittent and not very often. Now, it occurs frequently and continues for several minutes, although it is still intermittent. The whistle seems to be coming from the brake pedal. When the pedal is depressed, the whistling seems to stop. What in the world is going on and is it dangerous? Thanks in advance.

Reply to
Ellie Rose
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Ellie Rose did pass the time by typing:

Could be a few things including a leaking break booster. Worst case you would be left with standard brakes but it takes a looooong time and eventually the whistle will sound like a diesel trucks air brakes.

You can test the booster with a small vac pump, just remember do NOT exceed

14" of vac, just pull it down to 10" or so and watch. If the needle creeps up it's leaky and needs to be replaced.

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's the overblown metal one, the plastic version is just fine forthe garage and is about $10 at most auto parts stores. Have you cleaned the throttlebody and the idle air passage? Just putting on the brakes changes the idle air motor and could make a whistle. Thing is whistles are hard to locate.

Reply to
DougW

I know you said brakes related ... but here's a thought ... my old heating/cooling fan whines a bit now and then in winter on low speed. No big deal ... yet :-)

Reply to
bowgus

Check your vacuum lines on the driver side of the engine. Vacuum pulling through a line will whistle too.

Reply to
HarryS

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