sgolds

When the car is running I get a whistling sound from the brake pedal area when pressing the brake, it only whistles when the pedal is moving. I don’t think it does it when in Park, only starts when in D or R.
I don’t think there are any vac lines connected to the brake pedal in a 66 Toro? It’s def under the dash near your right feet. Kind of intermittent, sometimes does it and sometimes not.

jaunty75

I don't know if they did this in '66, but my '77 and '78 Toros have a vacuum line that runs to the brake pedal. It's a second way (along with the electronic disengagement that happens through the brake light switch) that stepping on the brake cancels the cruise control. Stepping on the brake pedal breaks the cruise control vacuum and causes it to disengage.

Does your car have cruise control? Does it work?

rocketraider

66 cruise was still electric motor-driven with no vacuum connections unless it's aftermarket. My thought is a small vacuum leak on the power brake booster. Do you notice a rougher idle when this happens?

sgolds

It’s a possibility but I’ll have to check again. The noise stops when the brake pedal stops moving, and I don’t think it happens in Park either. I don’t have cruise or auto parking brake as far as I know

oldcutlass

It could be the exhaust breather is clogged on the vacuum booster or the booster is starting to go bad.

joe_padavano

That is the air admittance valve on the power booster. With the pedal released, there is engine vacuum on both sides of the diaphragm in the booster. When you press on the pedal, atmospheric air pressure is admitted into the backside of the booster, which presses on the diaphram with 14 PSI to give you the "boost" from the power booster. If this valve is sticky or had dirt in it, you can get a whistle. If that indicates a restriction in the valve, you'll start to notice reduced braking assist from the power booster.

It's the part called the "poppet valve" in this diagram.

sgolds

Thanks for that, so it means the booster is going bad?

cfair

The way I found my booster was going bad was the motor smoothed out a lot when I disconnected the booster and plugged its vacuum port on the engine.

Once the booster line wasn’t a vacuum leak to the engine, it was pretty clearly time for a new booster. I think I might have had mine rebuilt, can’t recall.

They can eventually go bad, especially after 55 years. Surprising how well the vacuum components hold up in my ‘66 cars.

They’re so good, they make us question whether they’re going bad.

Cheers
cf

sgolds

I wonder if they don’t sell new ones if they might sell rebuilt ones in the local auto parts place?

joe_padavano

See my response in your other thread. This is a one-year-only application for a car over a half century old with extremely limited numbers still on the road. NAPA says none are in stock for shipment, and "call store for availability", which is their code for "lotsa luck". Most sources will rebuild yours when you send it in - they have no cores to rebuild otherwise. Sure, there's a small chance that you'll stumble onto a parts store that has had one on the shelf for the last 25 years. I hope your luck is better than mine for that. These are cars with limited popularity, small numbers surviving, and there's no business case for a company to stock one today when it might sit there for 5-10 years. Fusick doesn't have any, and they are the most likely source.