Air in the lines

[cubewhiz]

All of a sudden on my way home from work the other day, the brakes went right to the floor. They would provide a little braking, but not much. They feel spongy, so I'm pretty sure it's air in the lines. I'm not losing fluid, however, so I'm not even sure how the air got in there. I'm going to bleed the brakes tomorrow, but is there something else I should be looking for?

 

[adsm08]

Pull the drums, make sure your slaves are not blown out and hemorrhaging. If not, you probably just lost the master cylinder.

 

[cubewhiz]

Pull the drums, make sure your slaves are not blown out and hemorrhaging. If not, you probably just lost the master cylinder.

slaves? are those the wheel cylinders?

I just replaced the master cylinder when I did the booster in May. :/

 

[adsm08]

Yeah, wheel cylinder, slave cylinder.

You don't just get air in the lines suddenly.

 

[cubewhiz]

Yeah, wheel cylinder, slave cylinder.

You don't just get air in the lines suddenly.

Yeah, that's what I figured. It is supposed to be a sealed system. I'll check the wheel cylinders tomorrow. Is there anything in particular I should be looking for? Wetness, perhaps?

On a related note, I noticed that there are two sizes of wheel cylinders--one for 9" drums and one for 10" drums. Which would I have on my Ranger?

 

[kcm1582]

If they are leaking you will know it. Everything in the drum should be dry, if not you have a leak.

 

[adsm08]

You should have 9" drums.

And look for fluid gone everywhere.

Fill the reservior, have someone pump the brakes and look for fluid all over the whole system. After thinking about it, it almost sounds like you blew a front line.

 

[Andy D]

22 yr old rust belt truck. I would be checking out hard lines just 'cuz

 

[cubewhiz]

Okay, so I checked the wheel cylinders and master cylinder and there was no leak. I also checked all of the hard lines and there were no leaks there either. I bled the brakes anyway and there was no air in the lines. The fluid was dirty--a dark black color, so I bled with clean fluid until clear. The pedal still doesn't feel right, though. The first half of the pedal doesn't seem to do anything. The brakes in the second half of the pedal seem to work fine, though. Any new ideas?

 

[adsm08]

Does the truck have ABS?

 

[cubewhiz]

Does the truck have ABS?

yeah. you think maybe the abs is the issue?

 

[adsm08]

Could be a leak internal to the ABS unit.

 

[cubewhiz]

Could be a leak internal to the ABS unit.

Hrmm, is that the gold block thingy that the hydraulic lines run through?

 

[adsm08]

yes.

 

[cubewhiz]

After taking it to work and back, all seems well.

Thanks to all for the help.