So here it is... if the engine is turned off I can build up pressure in brake system and after a few strokes, the pedal barely moves (as it should). But as soon I start the engine, I can barely get any pressure.

The background?
It's a 93 Delsol si
I just did the brakes all around and I changed the calipers in the front. When I swapped the calipers I drained the front brake lines as much as I could before I removed the banjo bolt to slap it on the replacement caliper.

Master cylinder?
Gigantic air bubble in the lines?

 

Yea sounds like air in the lines. The fact that you can build pressure when the car is off most likely means that your master cylinder is fine. However when you turn it on, the brake booster applies more force,making the air in your lines compress. Do a very thorough bleed and you should be fine.

 

In this case, do you think I should bleed the brakes with the engine running?

 

When i bleed the brakes, i let the engine run. Some people dont and just sit and keep pumping the brakes. If you can find another person to help you bleed the brakes, can prolly knock out all 4 wheels in an hour or less.

 

30 minutes flat with the girl friend pumping the brakes

 

you must be a lucky man with that kinda girlfriend

 

dude they should be doing that **** anyways. we deal with all their bs... that's like the gf's moment to shine and at least pretend to be interested in what their man does... plus its not like actually working on a car and getting dirty lol

but def sounds like air in the brake line...

 

So I tried bleeding the brakes with the engine running and I'm getting the same results.
There is plenty of fluid coming out of the nipple when I bleed, but I just can't build any pressure in the system.

Could it be bad calipers?

 

It sounds like your master cylinder is bad. The seals inside the cylinder can wear out and wont build pressure.

 

That's a possibility. I just find it odd the master cylinder would go bad as I'm swapping calipers...

 

try this.. pump the breaks with the engine off hold the pedal then start the engine and let me know what happens.. weather hte pedal stays ware its at or it drops.. then go under the hood and disconect the hose going from the manifold to the break booster if air doesnt come out of it (and youll hear it) you need a new check valve that gose in between the booster and the manifold.. (thats what it sounds like it is to me)

 

I won't be able to try it until I get off work, but what would it mean if the pedal goes to the metal when I start the engine? What would it mean if the pedal stayed where it's at?

 

here's a little update.
I just found my Honda manual and it turns out I bled the brakes in the wrong order.
I went rear right, rear left, front right, front left instead of...
rear right, front left, rear left, front right.

Who knows... maybe that's my problem. I'll bleed again tonight, I'll also try what Murk said, but I'd still like to read some of your opinions.

 

thats not gonna be the problem.. its suposed to be that way but it wont effect much.. i did mine "wrong" and still stopped
well whats supposed to happen is you pump the pedal with the car off and it gets firm then you start the car and its supposed to go down "a little" and stay there then shut off the car and pump the breaks again and its supposed to get firm again..
thats gonna test your booster, check valve and ms
after that test take the line off from the booster your supposed to hear "stored air" come out if you dont then your check valve is bad.. basicly you can test your whole break system with these 3 tests in 1

so do the tests and let me know what happens ill let you know what your problem is.. now if you have air in the system your still gonna have a pedal its just gonna be spungey depending on how much air is in it.. if your ms is out your gonna have a very firm pedal or a low pedal.. if your booster is out again its gonna be very firm if your check valve is bad its not gonna hold pressure in the booster .. if none of those are the problems check your vacuum in the manifold make sure your making the right/steady vacuum

 

When I did your test, I would get good pressure with the engine off, then the pedal would rather quickly drop to the floor once the engine started.

But I fixed my problem.
I bled my brakes a third time yesterday night and everything is fine now.

 

bleed brakes again
starting from furthest away from master cylinder

 

thats suprizing.. iv never heard of it acting like that with incorrect bleeding
well good thing you got it fixed

 

It could be the begining of a bigger problem down the road? Or maybe there was just way too much air in the brake lines? I did the bleeding alone this time around. The previous 2 times were done with my girflriend pumping the brakes but yesterday I was on my own... So I didn't get to see exacly what came out of the bleeders.

All 4 corners were gravity bled for a few minutes, and finished with 3-4 pumps of the brake pedal.

 

this thread has some of the dumbest ****ing suggestions

lmao... are you serious?

engine running... don't bleed brakes with the engine running

this is correct

bleed them properly... google it. slow and smooth

 

I have a very similar problem. I am not that fluent in brakes at all.
here are my syptoms :
-93 eg6- stock brake syst
when i recovered my car I bled the brakes. starting from the furthest point ( rear pass) the pedal slowly became stiffer from corner to corner. I drove the car the next day and the pedal was softer, but the car barely stopped! very scary.

I returned a week later to rebleed the brakes FULLY. the fluid coming out is completely dot3/4 clear color. When I turned the car on, the pedal sunk significantly, and then I decided to walk away from the car, dejected.

anyone else have a similar experience?
suggestions please

 

Depending on how you bleed brakes you can worsen the issue of air in the lines. Have your pumper, pump in nice long slow pumps, pumping quickly can aerate the system. Make sure the two of you are in sync, if the pumper lets go while the bleeder is open air can be drawn back in.

To speed up the process do not let fluid leak out and drain the system instead cap or plug the line (although it much easier to mount the new caliper while the old one is still attached to the line and then simply swap over the lines), although when you install the line in the new caliper, open the bleeder and let it sit open, do not touch the pedal, allow the bleeder to sit open until a solid stream of fluid is coming out, this will purge the caliper of most of the air (this is called gravity bleeding IT DOES NOT COMPLETELY REMOVE AIR).

Good luck, bleeding a system should take no more than 10 minutes really.

 

Idk if anyone has said this but on my ej1. The repair manual states that the brakes should be bled in this order

rl
fr
rr
fl

it goes on to say that the rl and fr brake lines are on a seperate??cylinder?? Than the rr an fl

Hope that helps you out some

 

i'll try that system. I was under the impression that the series is rear passenger side, rear driver, front passenger, front driver.

 

Yes this is true for MOST vehicles. But the Honda service manual specifically states
LR-RF-RR-LF because the LR & RF are on the same feed from the proportioning valve and the RR & LF are on the other.

 

The car got a new master cylinder and the system was believed to be bled completely, as we went over it 3 times. I felt the pedal did not feel right, but my friend who deals with cars alot more said it felt fine. One week later, it has regressed to the same symptoms as before.