Having finally finished changing the rear shock absorbers and the left rear brake assembly I am now on the trail of an older problem that came with this car when I bought it four years ago.

When I push the brake pedal an obvious 'whoosh' sound emits from the area of the brake pedal master cylinder and booster. It is most clearly heard inside the car rather than when one is listening outside the car with the hood open.

The idle of the engine alters when the brake is pushed.

My strategy is to change the hose from the intake manifold to the check valve, this being the cheapest part to change, even though it appears to be in good shape. Then to change the check valve and then to change the booster if the previous efforts fail.

Local charge for the check valve is fifty Canadian dollars. If anybody knows where I can get one for less than that. I haven't yet costed out a booster but I expect it will be pricey. Not sure if it could be rebuilt.

I am assuming that if I go through this process the brakes will firm up. Right now they work well but the pedal feels mushy.

I tried to find some answers to this online and here but most replies are addressed to later model cars.