kicken90crxsi

I have a 93 civic with type r 5 lug an integra booster n master cylinder . All the brake components are brand new besides booster . I recently replace master because I was having a problem with the front calipers getting stuck on . Now everything bleeds great when vehicle is off pedal feels perfect n then as soon as I start the car they go soft n almost to the floor any help would be great

daxr

First check for the obvious - make sure you have no leaks. Pump it a bunch of times and check for fluid running out at the connections - at the master and at the wheels. That's not always easy as you may have a bunch of fluid laying around from the bleeding process, but spray things down with brake clean and let it dry off.

Its probably not a leak if you were careful, but that's easy enough to rule out.

If its not a leak and the pads are all seated and everything is put together right, then you have air in the system. If you replaced the master, did you bench-bleed it? If you didn't then its probably air in the master. Take it off and hold it in a vise so you can bench bleed it well.

The other possibility is a defective master, but if you bench bleed it and close off the ports you can test for that too - you should be able to apply solid pressure and feel no loss leaking down.

The other thing to check is pushrod length. The pushrod from the booster should just short of contacting the primary piston in the master when its installed. If all that's ok, then you got air in the lines somehow, and it can take some work bleeding the whole system out. A shop with a pressure bleeder could do it easily but with some patience and someone to pump the pedal it can be done in a driveway.

kicken90crxsi

No leaks triple checked that . bench bled master before I installed got all air out of it . And yes pushrods is just short of contacting piston and I have a little pedal play wen I touch brake pedal before it pushes back end of booster rod in

daxr

A defective master would be the most likely answer then. Usually if its bled well and you're careful you can just bolt it up and get a decent pedal. Cracking the lines at the master with light pressure on the pedal should get another bubble or two out of each, but it should be good to go from there.

If you take the master back off and plug the ports (easier said than done sometimes, as you don't always get plugs that fit well) you could verify that on the bench - if the master's bad the piston will go down under pressure; if its good it will hold pressure.

kicken90crxsi

So bench Bleed the new master installed it made sure no leaks and bleed entire system and still have same problem

daxr

Either a defective master, or you're doing something wrong. Probably a defective master. I've put on a few that had problems - one with a porous casting, two with line seats that weren't machined right, one where a plunger seal was put in backwards, one where a plunger seal was laid over so it didn't seal. And so forth. If you know what to look for its easy to take a master apart and see what's wrong, but if you don't just take it back and get another.

kicken90crxsi

So I rechecked all fittings for leaks talked to my friend he said sounds like a shuttled porp valve so I tapped on it. And stated car pump the brakes and voila had half a pedal took it for a drive pedal came up to just over 3/4 drove it to work and on way home front calipers grabbed n suck on any ideas I'm soo frustrated