I am having some issues with my brakes on my '89 CRX si. The problem is that the pedal is pretty solid when the car isnt running but when it's running the pedal goes to the floor. I have tried bleeding the system several times and it doesn't seem to fix the issue?

What would cause the brakes to just lose pedeal pressure once the car is turned on?

 

Not sure but my guess is the master cylinder needs to be replaced. With my old EF when it went out you would have to pump the brakes in order to stop and the peddle would go from being real soft and pushing to the floor to rock hard with a lot of pressure but it would spot eventually.

 

you may need a new booster. Have you checked the check valve.

 

 

wats the check valve? i am having the same problem and i am buyin a new master cylinder soon

 

How do I check the check valve to make sure its working right? The check valve is inline with the hose that connects to the Intake Manifold and the brake booster right?

 

yep thats it. Just take it out and blow through it. If it is working then you can only blow one way. If you can blow both ways then its bac.

 

Alright, thanks. I will give it a try in the morning.

I hope it isn't the MC, if it was I wouldn't be able to have good pressure on the pedal when the car is turned off right? Or doesn't sink to the floor or anything when the car is off as well. Just as soon as I turn the car on it just will fall to the floor when I press on it.

 

i didnt meen check the check valve lol. the check valve is there to see if the brake booster can hold negative pressure. all you have to do to test the brake booster is pull the hose off the right side of the valve (or the hose on the side that leads to the brake booster) and if it makes a sound similar to releif of pressure then its good... if it dosnt then it needs to be replaced

-best time to check is like a half hour to an hour after driving the car

 

erm, I don't think driving it right now would be a good idea since I my brakes just go away as soon as I turn on my car.

 

then just start it up and let it run for a little bit... then shut it off and wait for 30 mins and then check

 

Alright sounds good, I will let you know what happens in the morning Thanks for everyones input so far

 

Update:

The check valve seems to be working okay. I tried to re-bleed the system again and still no brakes. I guess the next step would be to get a new MC?

 

Did you just do the brakes ? did you adjust the rear breaks and the emergancy brake cable ? If you dont adjust the rears no amount of bleading will give you a firm pedal.

 

I recently did a rear disk conversion. So I replaced the ebrake cables, and put on new lines on the rear. Any info on adjusting the rears?

Also the car has been sitting for a good ~3ish years.

 

Anyone eles?

 

I guess I will go and buy a new MC in the morning?

 

try this with the car off pump the brake a few times till it gos down 3-4 inchs then start the car if the pedal gos to the floor the brake booster is good if not its your booster. now with the car on pump the brakes a few times till the pedal drops a few inchs now hold it down and shut the car off it should go up a little if not its you master cyl.

hope this helps

 

Thank you! I will try that first.

 

Going by this it is for sure my master cyl. Thank you, I will buy a new one and see if that solves everything.