Bleeding Brakes (1 Viewer)

[TexYoung]

I just bought an FJ40 and replaced the front brake shoes. Before and after I replaced the shoes, the front left brake was grabbing and pulling the vehicle to the left when brakes were hit hard. I had great pressure at the pedal, just pulling left. I decided to bleed the brakes and see if that helped. I started to bleed the brakes as I have done this many times on many other vehicles I have owned but never experienced what I experienced with these brakes. I made sure the reservoir had plenty of fluid and the cap was on. I placed a tube over the bleeder and ran it into a glass jar with brake fluid. Had my helper pump the brakes and then hold pressure on the pedal while I opened the bleeder. The first couple of times I did that air and fluid came out and into the bottle as it should have. I continued to do that but on the 4th time and all future times I did it, nothing came out when I turned the bleeder, no air or no fluid. I tried the other bleeder on that wheel and nothing. I tried the 2 bleeders on the right hand side and nothing. When I open the bleeder the brake pedal still goes to the floor, but no air or fluid comes out????? Now the pedal is mushy and the brakes barely work. Do I have plugged lines?? I have never experienced this when bleeding brakes before.

 

[Curt]

Well you already have squishy brakes try removing the bleeder completely see if it is plugged

 

[TexYoung]

Well you already have squishy brakes try removing the bleeder completely see if it is plugged

I will try that but I cant imagine all 4 bleeders are plugged.... Good place to start though. Thanks!

 

[Curt]

Front and back brakes are on different lines, funny that both wouldn't work. Check to see if the master is operating correctly, maybe your seals just went.

How long have you had the 40 and was it sitting?

 

[Pin_Head]

The master may be bad.

 

[shawnfj40]

The Master Might be bad (now). When your bleeding brakes (especially old ones), the peddle travels much further causing the piston in your master to do the same. dragging your old seals over new terrain is what wipes out the seal. if your getting no air and no fluid the master is shot. I have never seen one move nothing though. they almost always try some. Check the bottoms of your reservoirs and make sure they are clear and not plugged with goop.

 

[TexYoung]

Front and back brakes are on different lines, funny that both wouldn't work. Check to see if the master is operating correctly, maybe your seals just went.

How long have you had the 40 and was it sitting?

When I mentioned all 4 bleeders, I meant the 4 bleeders on the front two brakes as each front wheel has two bleeders. When this problem accourred I decided not to mess with back brakes until I figured this out.

 

[TexYoung]

The Master Might be bad (now). When your bleeding brakes (especially old ones), the peddle travels much further causing the piston in your master to do the same. dragging your old seals over new terrain is what wipes out the seal. if your getting no air and no fluid the master is shot. I have never seen one move nothing though. they almost always try some. Check the bottoms of your reservoirs and make sure they are clear and not plugged with goop.

I will check the bottoms of both the back and front reservoir to see if there is gunk and also try removing the bleeders to see if they are clogged. Would it be a good idea to take of the bleeders and run compressed air through the lines to check for plugs there as well?

 

[TexYoung]

The master may be bad.

Do you think it has anything to do with the brake booster?

 

[TexYoung]

Front and back brakes are on different lines, funny that both wouldn't work. Check to see if the master is operating correctly, maybe your seals just went.

How long have you had the 40 and was it sitting?

I have only had it for a few months. It had been sitting for 2 years.

 

[Curt]

Bad booster is most likely a hard pedal. masters usually have the soft squishy feel. When my master went i could see the fluid rising in the reservoir as pressure was applied to the pedal. The master can leak fluid into the booster, this can be checked by removing master from booster and looking between them.

Mine sat for 3 years.

 

[Pin_Head]

No, it is not a bad booster.

 

[shawnfj40]

Just for some clarity, when you stated that your helper pumped the brakes while you held tubing off your bleeder in a jar, was the bleeder open the whole time? If it was you may have sucked a lot of air in there. Try and bleed them by opening the bleeder and have the helper depress the peddle and hold it down until you close the bleeder. you might have to do it quite a few times before you expel any air. Once you hae seen some fluid your helper can pump the braes until they have some pressure then, hold the peddle down while you open the bleeder to let out any air. Once fluid/air stops, close the bleeder before letting the peddle up. Do this until no more air is expelled. Start with the bleeder furthest away from the master on each circuit.

 

[edwjmcgrath]

I have had this happen before. Bleeding the brakes causing the master to fail. This is definitely "a thing". As Shawn implied, normally the piston and seals in the master operate in a fairly small range. This can result in corrosion to build up in the master cylinder where the seal isn't running. When you put the pedal to the floor during the bleeding process, the old seals go over the corrosion and get cut or broken.

Edit: If you want confirmation, google "bleeding brakes causes master cylinder to fail", you'll find a dozen articles describing this syndrome.