1999Toyota Sienna 97,000 miles V6. The power brakes went out while driving. The brake pedal is very hard to depress. I have to practically stand on the pedal to make the car come to a stop. The brakes do not make any noise. Also, while depressing the brake pedal, the car seems to surge just a little. Any suggestions?
First see if (and I doubt it) there are any major vacuum leaks, if so plug and retest brakes, second, check the check valve on the booster, it should let air flow only one way. Last replace the booster.