This may help anybody else who replaced their brake booster and check valve for a hard brake pedal and got no improvement. I was finding it very hard to come to a stop going down a hill without standing hard on the pedal. I've been round and round with this problem and read every hard brake thread.
As a last resort I took it to the Toyota dealer to get a diagnosis. They were stumped, and wanted to replace the master cylinder and brake booster: $$$
I replaced the check valve and then the brake booster myself. Did not fix the problem. So I took it to a friend's mechanic who asked me a lot of questions I couldn't answer about testing vacuum. I left it with him and he called me back in a hour.
- He said there was vacuum through the hose going to the booster but Just not enough volume.
- Possible fixes:
1. clean out and VAT the intake section on top of engine. about 300 to 400 bucks.
2. he routed a vacuum hose from another source to the booster. Brakes working GREAT. I guess this is temporary fix till I do #3>
3. He suggested a cheap fix would be mounting a Vacuum cannister to route vacuum from. Maybe 50 bucks.
I'm not a mechanic and may not be using the right terms but passing this along if it helps anybody . . . . and the dealer don't know s%#t.