Chrysler 300M

I own a 1999 300M that has recently started emitting a high pitched noise from under or behind the dashboard on the driver's side. The noise starts a few minutes after starting the car, and can be stopped by tapping the break pedal. The noise usually comes back in a few minutes, but sometimes not for quite a while. If the noise is present when shutting the car off, it persists for a couple of minutes, then stops. The sound can also be heard outside the car, but I am having no luck locating the source. The brakes, and all other systems, are functioning as designed as far as I can tell. The noise is very annoying. Any help resolving tis issue will be greatly appreciated. Thanks!

Reply to
randymurphy
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Reply to
69GT4spdtrac-loc

Not that it's much comfort, but, according to the following thread on the 300M ezBoard, several people there have had the problem:

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It doesn't appear to have been more than an annoyance for anyone. One person said it was traced to a brake booster problem, and the noise went away when the booster was replaced. Strangely, on my '99 Concorde (essentially same as 300M), I have a noise that behaves the opposite: The noise is not present until I apply the brakes (not rotor or pad related since it will do it with the car sitting still and the engine running). The noise will continue with the brakes applied for a second or two after turning the ignition off, which tells me it is vacuum related.

I have a feeling both of our problems would be resolved by replacing the brake booster. If the source of your noise is the same as mine, the noise will be louder with the hood open than when sitting in the cabin. It does appear to be coming from the general area of the booster, but because of the super-high pitch, is hard to localize further than that.

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Reply to
Bill Putney

I knew a husband-and-wife couple from Arizona who used to drive their his-'n'-hers '75 Dart and Valiant around the country to Slant-6 Club shows every spring and summer. The Dart had a musical brake booster: Apply just the right amount of pedal and you could practically make the booster whistle Dixie...

-Stern

Reply to
Daniel J. Stern

I have (or had) a similar problem with the booster in my '84 Voyager. A former student (1985ish) who is a journeyman CC tech and who also teaches automotive (Vo-Tech) training at one of our local high schools and who does CC work at his home (He has an incredible line up of customers who keep hassling him for his time) told me what the "problem" was caused by... Anyways, he told me it has to do with the "valving" in the booster. I looked into the CC service manual (FSM) and it is rather skimpish on the booster details. However...

They eventually start malfunctioning even though the booster more-or-less works. The noises are due to the malfunctioning valving.

I was all set to get a replacement since I was going to strip the interior and replace the '84s interior with a "mint" interior from an '85 (or was it an '86??). Easy to do when you are replacing the lower front panel.

Now I notice the hiss is gone! No matter. I will STILL replace the booster as they do NOT heal themselves. intermittent noise now means future trouble. Intermittent problems are a PITA to diagnose etc. Fortunately for me I understand what the problem is and how to solve it. I will save potential booster trouble by taking care of the intermittent trouble now and replace it with CONTINUOUS quiet. A relatively cheap fix. Guaranteed by replacing the booster. They don't heal themselves like a broken limb. Been there, done that.

Ken Winnipeg, Canada

Reply to
Ken Pisichko

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Reply to
randymurphy

Heh heh! Like working on rotors and pads will have some affect on a high pitch noise that is present with the car sitting still. Scary, ain't it! (I mean the dealer, not the brakes).

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Reply to
Bill Putney

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