Brake booster or master cylinder?

[miguelmcv]

The valve that Miquel is talking about is the proportioning valve, not the check valve. Ignore him.

The check valve is the lump in the hose between the intake and the booster. When it's broken (or backwards), you'll have the symptoms described by the OP. Verify that air can flow from the booster to the intake, but not the other direction. If the valve passes this test, move on to checking the booster, itself, for leaks, as suggested by Bryan.

Sorry, My bad, I thought they were talking about the proportioning valve.

I can't tell anything else, which there are so many replies about where is the check valve and would be just repeating over and over.

Good luck, and hopefully is just your check valve that is leaking.

 

[TrevorS]

Ok ill bleed them out today after work and check the valve. I don't remember a lump in the Jose to ill have to check that.

From what you said, you only bled half the MC. It would probably be a good idea to back up and start from scratch. Remove the MC and reservoir and perform a bench bleed on both halves. When it's fully bled, move it and the reservoir back to the car and without spilling any fluid, reinstall. Then start again on the caliper bleeding. Mine is a '90 and the 1G has two diagonal circuits, don't know if the 2G is different.

^^ Its easier with it running, in my opinion...

I always do it with the engine off and works fine -- different strokes I guess !

 

[GSLENK]

Whatever you do, do not let the reservoir empty out during the process. I lunched out and ran it empty on the last caliper bleed. So I started all over again from the passenger rear. better safe than sorry.

I always refill the reservoir after each caliper line is bled, then move to the next. also its not hard at all to bleed with the engine off, I would imagine its more controllable.

 

[Ace_gst]

Think i can just work the air out the front.

 

[Ace_gst]

Well i bleed the brakes again and i am still getting soft brakes if any at all. I have never had this much trouble with brakes before. I have to be missing something just dont know what.

 

[bryanwheat]

Are you sure that the person holding the pedal isn't releasing it before you tighten the bleeder?

 

[Ace_gst]

Yea ill tighten it up while its still spraying out. I can pump them and get them simi- stiff but as soon as i start the car they go limp. I have made sure the check valve to BB is good and on the right way but still nothing. Wondering if i can effeminate the booster by plugging the vac line and try that out.

 

[kchaazz]

Yea ill tighten it up while its still spraying out. I can pump them and get them simi- stiff but as soon as i start the car they go limp. I have made sure the check valve to BB is good and on the right way but still nothing. Wondering if i can effeminate the booster by plugging the vac line and try that out.

Did you bleed the master cylinder the way I described previously? If you installed the master cylinder dry, it can be a pain to get the air out of the master itself. There are two lines attached to the master cylinder, each line runs a diagonal circuit- one for front left/rear right wheel, one for front right/rear left wheel. You can bleed the master cylinder by cracking one line at a time- hold a towel to catch the fluid and bleed it the same way you would a caliper. If you were bleeding the the calipers in the correct order- right rear, left rear, right front, left front, then the only thing left is the master cylinder.

 

[jtmcinder]

Yea ill tighten it up while its still spraying out. I can pump them and get them simi- stiff but as soon as i start the car they go limp. I have made sure the check valve to BB is good and on the right way but still nothing. Wondering if i can effeminate the booster by plugging the vac line and try that out.

As much as I enjoy posts that include the words "limp" and "effeminate," the lack of any mention as to whether your check valve is working or your booster is leaking is getting annoying.

 

[bryanwheat]

Did you bleed the master cylinder the way I described previously? If you installed the master cylinder dry, it can be a pain to get the air out of the master itself. There are two lines attached to the master cylinder, each line runs a diagonal circuit- one for front left/rear right wheel, one for front right/rear left wheel. You can bleed the master cylinder by cracking one line at a time- hold a towel to catch the fluid and bleed it the same way you would a caliper. If you were bleeding the the calipers in the correct order- right rear, left rear, right front, left front, then the only thing left is the master cylinder.

If there is fluid coming out the lines than the master doesn't have any air in it.

 

[kchaazz]

If there is fluid coming out the lines than the master doesn't have any air in it.

The master cylinder can still have air trapped in it even if fluid is making it to the calipers. Ive owned several DSMs and have had to replace the brake master cylinder in every one of them. He didnt bench bleed the cylinder to fill it with fluid before bolting it to the car, so hes going to have to crack the lines on the cylinder, one at a time, and bleed it.

 

[bryanwheat]

The master cylinder can still have air trapped in it even if fluid is making it to the calipers. Ive owned several DSMs and have had to replace the brake master cylinder in every one of them. He didnt bench bleed the cylinder to fill it with fluid before bolting it to the car, so hes going to have to crack the lines on the cylinder, one at a time, and bleed it.

Any air in the master will bleed back thru the reservoir. The reason for bench bleeding a master is to eliminate an air lock in the cylinder when it is completely dry.

 

[Ace_gst]

As much as I enjoy posts that include the words "limp" and "effeminate," the lack of any mention as to whether your check valve is working or your booster is leaking is getting annoying.

Yea not the best speller but if you read the post above i did say i checked to make sure my check valve was working and in the correct way. I cant say i checked the BB for leaks but when i start the car with my foot on the brake the peddle goes down but goes down all the way and doesnt come back

 

[Ace_gst]

Well it was both the master and booster giving me problems.

 

[kchaazz]

Well it was both the master and booster giving me problems.

What was the final solution to your issue?

 

[Ace_gst]

Brake booster shaft that pushes the master cylinder was broke inside the booster somewhere and was just flopping around. It is a 1989 so I suppose it was about due for a new one .

Thanks everyone for the help.

 

[forcefed_90tsi]

Sorry to reply to an old post, I have a similar issue so I read every reply and now I think i can tackle this issue. Thanks everyone!