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Caliper won’t bleed

chris85

chris85

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I mentioned this in my build thread but I wanted to see if anyone has any ideas on this.

So bleeding the brakes and both rear calipers won’t bleed. Fluid is making it to the caliper, but when you open the bleeder valve nothing comes out. No obvious leaks. :dunno: I’m clueless.
 
rust build up in bleeder screws ? most comon thing i can think of to no flow out .

have you pumped the pedal and held it and cracked the hard line at the flex hose to verify fluid WITH pressure is getting down that far ?

and fyi: those little rubber caps on bleeder screws keep them open / free of dirt / rust / junk that can and does freeze them up solid .
 
Both rear? Is this a disc brake conversion?
 
sweetk30 said:
rust build up in bleeder screws ? most comon thing i can think of to no flow out .

have you pumped the pedal and held it and cracked the hard line at the flex hose to verify fluid WITH pressure is getting down that far ?

and fyi: those little rubber caps on bleeder screws keep them open / free of dirt / rust / junk that can and does freeze them up solid .
Click to expand...

We cracked at the banjo under pressure and had fluid. They haven’t been capped so rust is pretty likely.


Bent77 said:
Both rear? Is this a disc brake conversion?
Click to expand...

Yes
 
pull bleeder screw out .

take drill bit and clean hole out . but dont go deeper than stock hole depth . best to just grip drill bit in vise grips and hand turn it out .

rinse gunk / junk / rust out with parts cleaner and re-install and bleed out system .
 
Maybe your calipers are mounted on the wrong side? Meaning...the left caliper is on the right side and visa versa.
 
1-ton said:
Maybe your calipers are mounted on the wrong side? Meaning...the left caliper is on the right side and visa versa.
Click to expand...

He'd still get fluid out but have an air pocket.
If the bleeder is pulled off and fluid comes out then just get new bleeders or, as said, try to clean those.
 
Just went and checked something real quick.

So pulled the screw with no pressure and there is fluid coming through the caliper and it looks like there maybe fluid coming through the screw as well. :thinking:

I’m wondering if it could be the master cylinder. When we were pumping, fluid would shoot up from the rear tank(front brakes) but not the front.

Prop valve is 50/50, don’t know if that would matter.
 
I replaced the master cylinder on my van thinking it was junk from sitting,when I couldn't get any fluid out of the rear wheel cylinder bleeders after I replaced the long steel line to the rear brakes and one from the master cylinder to the junction block..

When I first went to apply the brakes before doing anything,the pedal was "stuck",like it had rusted up the master cylinder bore,it sat so long..it broke free with more effort,then seemed to work,but I assumed I tore the rubber seals up in the master cylinder--so I got a rebuilt one..

After I replaced the rotted steel lines and installed the rebuilt master,and bench bled it--
I could pump up the pedal on both the original and replacement master cylinder until a firm pedal was obtained,but if I let off the pedal and pushed it again,it would go right to the floor,with zero resistance ..then I decided to take the bleeder screws right out of the wheel cylinders,and pumped the pedal until it became hard again (which I knew shouldn't happen !)--and not a drop of fluid came out of either one..

I then decided to unscrew the new steel line at the rubber hose on the rear end,and got douched with brake fluid!..so it was getting that far,but no further..

Turned out the old rubber brake hose that looked fine externally had plugged up tighter than a bulls a$$ in fly season!..I put one on I had saved from my pickup that was only a year old and Ta-Da--the wheel cylinders got fluid ,I bled them,and the brakes work perfect again..

I may have been able to get away without replacing the master cylinder,but it was a 1981 original,I decided the $20 to replace it was a good investment..

Ditto for the rear hose--after I thought awhile,I realized back in the late 90's I had replaced the front calipers for nothing,when they started dragging and smoking--so did the rebuilt ones,the very next day.!.I then learned both original front hoses had failed internally,replacing them solved that issue too..

Brakes can be a real pain to get to work right sometimes..usually the bleeding process is what gives the most grief ...
 
This is all new stuff except for the master cylinder.

Stainless steel lines and prop valve from inline tube.
Flexible lines from ORD
Calipers came from a Lugnut 4x4 kit.

It’s all been installed almost 2 years but just now needing to bleed and get them functional.

Guess I could pull the MC and try to bench bleed it and see if it’s seized up?
 
chris85 said:
This is all new stuff except for the master cylinder.

Stainless steel lines and prop valve from inline tube.
Flexible lines from ORD
Calipers came from a Lugnut 4x4 kit.

It’s all been installed almost 2 years but just now needing to bleed and get them functional.

Guess I could pull the MC and try to bench bleed it and see if it’s seized up?
Click to expand...


THIS INFO would have been helpfull in the 1st post .

yes sitting dry and no use might have stuck the master up possibly .

start there and bench bleed it . then try again . dont forget farthest wheel from master first then next closest wheel .
 
I just bolt the master cylinder up to the booster or firewall and use the bleeding tubes supplied with the rebuilt one to bleed it on the vehicle ,its a lot easier than a vise on a bench..I used a spring type clothes pin clamped on the master to hold the bleeder tubes submerged..
 
nutt7 said:
Maybe you tripped the safety valve in the prop valve? It can be tripped while bleeding. I’m a little foggy on the function, but I think it can cause this issue.
Click to expand...

This will be the next thing I check. I took apart the MC and it isn’t ceized. Researched some more and found some info about the safety switch. The symptoms seem to match, trickling fluid but nothing on compression, so we’ll see.
 
try holding the pin from moving out as you pump the brake pedal .
the pin is under the rubber cap on the end/side of the prop valve . they actualy make a tool for this . but as said if the pin is tripped you get about no flow to the rear .
 
So it was the safety valve. You can seein the picture that hole is open. When I first removed the pin it was blocked off (forgot to get a pic). Pretty easy to move back. Haven’t bled the breaks again yet but I think I’ll gravity bleed first to get some fluid in.

27D65A06-3292-4764-A4FB-4EB4334A2F3A.jpeg
 
I had the same issue when I installed my 14 bolt with discs. Fluid would come out but could never get a pedal. Ended up being that deal in the proportion valve. Still dont have a perfect pedal but I think my master isnt up to the task but that's for another day lol.
 
So I’ve fooled with the rear brakes several times now and still no better. I even bought the safety switch tool.

I saw in an older post where someone suggested cranking it to build vacuum, but is there anything else to try?

I may pull the calipers off tomorrow and make sure the cylinders aren’t seized but that really shouldn’t effect fluid pressure, correct?
 
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