trouble bleeding the front brakes

[Pete M]

so the truck has sat with the front hoses disconnected long enough to drain all the fluid out.  I'm finally doing reassembly and now I can't bleed the dang thing.  I bench bled the master so it's not that.  how do I reset the emergency shuttle?

[eaglescout526]

The emergency shuttle should just reset. I know when my front line burst and learned that mine works that I was able to replace the hose and bleed as normal. I think the only way that shuttle works is based on pressure from the pedal. 

[Ωhm]

Make sure the bleeders aren't plug.

[Pete M]

hoses and calipers are brand new.   neither side bleeds.  leaves me with the combo valve being the problem but, man, do I not want to have to break open all the lines.    but I guess I have to start tearing it apart to diagnose. 

[AZJeff]

The emergency shuttle often does NOT reset by itself.  Years of gunk (and never normally moving) make it stick in place.   It is possible to move the shuttle to the center by sticking a small pick or similar down in the hole where the switch plunger threads into the valve body, and I have done this in the past.  Just be gentle with the pick on the shuttle, since it's usually made out of aluminum.

[Pete M]

can't wait to try that out! 

[Pete M]

On 5/19/2024 at 6:17 PM, AZJeff said:

The emergency shuttle often does NOT reset by itself.  Years of gunk (and never normally moving) make it stick in place.   It is possible to move the shuttle to the center by sticking a small pick or similar down in the hole where the switch plunger threads into the valve body, and I have done this in the past.  Just be gentle with the pick on the shuttle, since it's usually made out of aluminum.

 

how easily should it move?

[jdog]

In a perfect world pretty easy. If it's gunked up it might take some small movement back and forth to get it free

[AZJeff]

3 hours ago, Pete M said:

 

how easily should it move?

It really should not take much force.  I use a small pick and kind of try to drag the shuttle back to the center.  It should also have an angled surface on it that actuates the switch plunger, and that surface is easier to use to actually push the shuttle along.  (That angled surface might be out of view through the switch port, but some slight coaxing might make the edge of the surface show up in the switch hole.  Once that surface is visible, it's easy to push it along the rest of the way towards center.)

[ratrapp]

dumb question but are your bleeder valves pointed up?if the bleeder screw is pointed down you'll never get it to bleed.

[Pete M]

bleeder valves are correct.  

 

nothing moves in the tiny hole.   starting to get desperate... I'm wondering if I can force it with some air pressure shoved up through the lines... 

[AZJeff]

If worse comes to worse you can take the prop. valve out of the vehicle, disassemble it, and push the shuttle back into place from one end.  (It might also be a good time to clean the whole valve to make sure any crud from within the valve assy.)

 

Of course, this will require bleeding ALL the brakes, but that's not actually a bad thing, especially if the fluid is old.

[Pete M]

at this point I'm mentally preparing myself for a wholesale changeover to XJ stuff. 

[fiatslug87]

@Pete M what did you end up doing?

[Pete M]

wholesale changeover to XJ stuff.  XJ front prop and eliminated the rear prop.

[pizzaman09]

You've reminded me of a problem I came across recently on a friend's Cadillac.  We replaced a caliper and absolutely could not get it to bleed.  Upon close inspection we found that the bleeder hole was not fully drilled through.  Always worth checking the new parts are built correctly when running into an issue.