Horn-like sound when I come to a stop in a '52 300

Posted by Thunderbolt On 2015/1/26 7:08:43

Sometimes when I'm slowing to a stop or stopped altogether the car makes a horn-like moaning noise coming from the front. It's slow and steadily gets noisier. I beeped the horns when it was happening once and confirmed it's not that. Yesterday I parked the car, removed the key, and as I walked away from her she made the the noise for a few seconds. That threw out my idea of an idler pulley and the intake. FYI she's got power brakes and I think its time for a new diaphragm - the pedal goes to the floor when it's hot. Could this be a strange vacuum noise?

Also thank you to everyone for your help.