One wheel won't bleed - wheel cylinder bad?

[jturner]

I'm pressure bleeding my brake system, and passenger/rear bleeder gets zero flow. I can back the bleeder out all the way and put it in my pocket, and nothing comes out of the hole it left.

 

Beforehand, I drained all the brake fluid, replaced all the flexi hoses, installed rebuilt front calipers, replaced the rubber lines at the reservoir.

 

All the other bleeders are flowing heavy when I crack them.

 

I loosened the hard-line fitting at the offending cylinder and it started flowing there, so I know it's not a line/hose issue between the splitter and the cylinder.

 

I'm not very experienced with drum brakes, what is my next step?

[Dudeland]

How is the master cyl?

 

[jturner]

4 minutes ago, Dudeland said:

How is the master cyl?

 

I didn't touch it, probably original. The same line feeds both rear brakes, wouldn't the other side have issues too if the problem was that far upstream?

[Dudeland]

I think you have maybe a pinched line or some debris in the system.  Also, I know it sounds weird, but sometimes the flex lines have dust covers on them when you get them.  Is there a chance one wasn't taken off when you installed the lines?

 

The good news is that you know the other side is getting fluid, so trace the other line back to the T-Junction, and check things from there. 

 

 

 

[jturner]

I loosened the hard-line fitting at the offending cylinder and it started flowing there, so I know it's not a line/hose issue between the splitter and the cylinder.

I know it’s flowing from the final line to this wheel’s cylinder, I just don’t know what causes a bleeder to seal off like that.



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[Simeon]

14 minutes ago, jturner said:

 

I know it’s flowing from the final line to this wheel’s cylinder, I just don’t know what causes a bleeder to seal off like that.



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Just some crud caught inside. Have a probe around inside the bleeder hole with a nail or similar. Note that the actual drilling in the middle is a lot smaller than the outside of the bleeder so use something fine. 

[jturner]

I rattled a pick around in there, but I didn’t know what I was looking for... I’ll do it again and try to find that hole (insert pun).

[Jimmy]

I just replaced all my flex lines, calipers, and wheel cylinders. I had a similar behavior with the rears as you describe. I shrugged my shoulders and moved to the fronts and got those bled somewhat, then went back to traditional method of bleeding starting at the right rear. The pressure/flow at the rears was MUCH better after bleeding the fronts somewhat.

 

I /think/ it might have to do with the extra lines to the front calipers being shared by the rear circuits. 

 

I'm not sure whether my experience meaningfully relates to yours or not, as I didn't use a pressure bleeder, but rather enlisted the services of the unfortunately located. ?

Edited May 26, 2019 by Jimmy
Fixed wink

[Mike Self]

3 hours ago, Dudeland said:

I think you have maybe a pinched line or some debris in the system. 

+ 1 on crud inside the wheel cylinder.  You may end up having to pull the drum and shoes, then dismantle the wheel cylinder (remove cups, pistons and springs, and unscrew the rigid line from the wheel cylinder casting.  Then clean the wheel cylinder's innards thoroughly with brake cleaner and poke a soft copper wire through that itty bitty hole that connects the brake line with the chamber inside the wheel cylinder.  That'll clean out the passage and hopefully allow bleeding.  

 

But before doing that, try bleeding with a helper pumping the pedal while you open an close that bleeder screw.  That method generates much more pressure than a power bleeder, and may dislodge any crud in those internal wheel cylinder passages.  

 

mike

[jturner]

I probably won’t have a helper around anytime soon... but my bleeder is a compressor, so I did increase the pressure to about 25psi to see if it would knock something loose. That was as high as I felt comfortable going, I usually keep it at 10.

Thanks for the run through, makes sense.

[dlacey]

Take the bleed nipple out and clean it...that cylinder very simple...if u got fluid on the inlet it can only be a blockage just there or the nipple...

[Stevenc22]

you can crush the bleed nipple if you over tighten. Take the bleed nipple out and inspect. You should get fluid then since the fluid is at the hard line.

[jturner]

you can crush the bleed nipple if you over tighten. Take the bleed nipple out and inspect. You should get fluid then since the fluid is at the hard line.

I took the bleeder out and put it in my pocket, no flow from the exposed hole.

I poked around in there and couldn’t get anything. I figure if I have new calipers, I might as well replace the wheel cylinders... I didn’t realize they were so cheap. I ordered a set of tii ones.