What could be causing a water gurgling sound when I brake?

Dear Car Talk

Dear Car Talk | Oct 01, 1995

Dear Tom and Ray:

I have a '90 Ford Tempo with a little over 37,000 miles. My problem is that when I apply the brakes and come to a stop, I get a gurgling sound like water splashing around in the front of the car. I have taken it to two different mechanics who checked the anti-freeze level, brakes, and heater and cannot find the problem. There are no leaks, either. Please help.

RAY: It's probably nothing to worry about, Marie. In fact, as long as you're getting sufficient heat and your coolant level is OK, you may want to just leave it the way it is. Personally, I find the sound of waves rather soothing!

TOM: There are two possibilities. One is that some rainwater may be trapped in the ventilation system. It's supposed to flow out through small drain holes, but sometimes those drain holes get plugged up, and need to be blown out with compressed air.

RAY: More likely, however, is that some air is trapped in your heater core. They may have checked the heater, but they didn't check well enough. The heater core is under the dashboard, and it's supposed to be completely filled with coolant from the cooling system. If there's air in there, you could certainly hear some sloshing.

TOM: Ask your mechanic to bleed the air out of your cooling system. Make sure you tell him you think there's air in the heater core, so they can do a careful job. That should solve your problem, Marie.

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