rt turbo

well. ive search and search, and had many threads of this poosted, still no positive answer on this problem... symptoms:
at a cold start, there is almost no pedal pressure, i pump a few times and it returns... now the kicker... after the motor warms up, the breaks start to grab the rotors slowing the czar down, they grab and release and then they grab so bad that i have to pull over. im pretty sure its all rotors grabbing, i hear the grabbing and squealing sound coming from both front and i think both rear...

we now think its the break booster gone bad, probably from the valve in the line running to the intake manifold letting in boost pressure. i think it may have slowly destroyed the break booster internals. now when i drive the car there is way way too much break pedal pressure. its almost hard as a rock. i want to have a definitive answer before i buy a break boost, and im ganna replace the master cyclinder also. what do you all think the problem is?

live2drive15

iTrader: (4)

You'd be wise to test your one way check valve on the vacuum inlet to the booster. If it is busted it would be letting boost pressure in which would cause your pedal to be super hard and could have possibly damaged your booster all together. I would start with the check valve and if that's bad, it might be just as simple as replacing it.

rt turbo

yep. thats what im ganna do today. il pull that line off, but if i remember correctly the valve is inside the line itself. il try a blow or vacuum test.

quicksilver_rx7

If you don't mind destroying the line, you can cut it to get the valve out to test it, and just replace the hose. I replaced mine with a silicone hose and never had any trouble out of it. I think I've got some of the hose left if you need it. Just stop by and you can have it.

Joe

rt turbo

well, i was able to do a quick check with the valve by blowing through it. but i dont think this is a positive way to check it. the side the needs vacuum would open up fine and let air through, the other side however, would not let any air through like it should... do you guys think it would need more pressure than what i physically could blow through it to open it if it is bad?

quicksilver_rx7

If the check valve is bad and it's letting air pass through, you will know it because you will hear a hissing noise coming from the Brake Booster when under full throttle and boosting; which is the diaphram in the brake booster bleeding off the excess air. You can also take the check valve completely out and see if that solves your problem. When I did my vacuum hose job, I initally forgot to put the check valve in the new line. I still had brakes, but I had a hissing noise from the booster's diaphram bleeding the air off, which is essentially a boost leak.

Joe

rt turbo

hmm, i dont think i hear that... can the master ccylnder cause my problems? i dont hink its the clipers because all breaks grab. they seem to grab worse when im in reverse.

rt turbo

so, can you guys say that because all my breaks are acting up its most likely not calipers, and somtnhing within the break booster or master ccylinder? im about at that point to just replace the break booster and master cyclinder. i found both for 225. i think one of those things will fix my problems. anyone else agree?

Gadd

Sounds like you may have lots of moisture in the system. When is last time the fluid was flushed? I'd start with that. If that does not fix it and your sure all four calipers ( or at least both front )are dragging, something must be going on with the master cylinder.

quicksilver_rx7

^ Agreed. I would definitely make sure you have covered all the bases with what you do have before you start replacing parts.

Joe