Bleeding a hydroboost master cyl.

[RICH MUISE]

Well, as usual the little things are chewing up lots of time. I blocked off the line to the rear brakes at the proportioning valve (removed the line and replaced with a plug), filled the reservoir, and hooked up the pneumatic brake bleeder I just picked up on a recommendation. I'm only working with the front lines now..backs are not hooked up. All of my line connections are tight and are not leaking. I've filled the cannister 5 times now and still get as much air as when I started, so I'm obviously doing something wrong. The fluid in the reservoir was never less than 1/2 full, btw. I just noticed there are two bleeder valves on the master. Sould I be starting there, at the top and working down and away instead of the farthest point (rf caliper)?

update...I haven't been able to bleed the master to the point where I've got pedal. I may have an issue with the hydroboost or master, or my pushrod alignment. The pedal moves about 2" then comes to a hard stop.  The boost/master were salvage yard items I got 4 or 5 years ago. I'm hoping to go look at my friends Mustang with a hydroboost tommorrow and see what his looks and feels like.

[canadian_ranchero]

are you bleeding the back line?

[RICH MUISE]

I have no line running to the back at all at this point. I plugged the outlet right at the proportioning valve. I'm just trying to get the front brakes working for now so I've got something. Back brakes won't be done until I pull the differential for the mods I want.
I tried to bleed the two bleedrs right on the master, seem to have gotten most of that air out, but when I checked to see if I was getting any pedal improvement, I wasn't. I actually get about 3" of travel with only return spring pressure before it comes to a hard stop.
Dumb question for the hour...is it posible the master's plunger is frozen. It did sit on a shelf for a number of years.
Dumb question for the next hour...is it safe to assume that the hydroboost is working alright because I have the power steering working? Or is the power steering fluid just being passed thru the hydroboost, and the boost isn't actually doing anything for the PS. In other words, If the hydroboost has an issue, it may not necessarily affect the ps as long as the fluid can pass on thru.?
With the original problem of bleeding in mind, Even if the boost had an issue, could it affect the bleeding of the master?
My brain is tired, I'm going to bed. I sure hope you guys got this all figured out for me when I wake up in the morning. lol

[BWhitmore]

Rich - Not being familiar with the hydroboost system, my only thought deals with the front brake calipers.  If the bleeder screws are not very close to being straight up you may never bleed all of the air from the system.  I had this problem on my Ranchero (non-power dual master cylinder) and finally realized that the front calipers were reversed-left to right.  When installed correctly with the bleeder screws facing straight up I was able to bleed the brakes with no problem.

[canadian_ranchero]

i might be tempted to bench bleed the master cylinder,to see if that is working

[dgasman]

Rich,
You need to bench bleed the master first. The master sits at a upward tilt on the mustang and will have a air pocket at the end . Next gravity bleed the line at the plug you have at the valve. Now bleed the front lines from the farthest (right front) to the closest(left front) this should give you a very good pedal. One question , why do you not want the rear brake lines hooked up? When I did mine all the lines were hooked up and after I bleed the master I gravity bleed the hole system and the car will stop on a dime and give you nine cents change.

[RICH MUISE]

On the bench bleed....I saw a you tube video where they were replacing a Mustang master and the guy doing it said that master did not have a check valve, so doing a bench bleed was of no use on that application. I had also read where with the pneumatic bleeder a bench bleed was not necessary. I obviously don't know if either of those were accurate.
On the back brakes....Many years ago when I had the body off and was redoing the frame, I pulled all the old brake lines and ran a new ss one down the frame to the back. The old oem drums will be replaced with discs when I redo the differential, so I haven't made new lines to hook up the old drums. I was just wanting to get the front brakes hooked up so I could stop the car if I actually used the drivetrain to move it around, load on a trailer, etc. Back brakes will be done before the car is driven.
On the bleed valve position....I was aware of the posible left-right wrong assembly when I mounted the Granada calipers and should have them mounted correctly, but I will double check. My bleeders are at the high position on the calipers, but they do not point straight up, they point straight back. If my memory serves me correctly, switching the calipers left to right puts the bleed valve at the bottom where it becomes a bleeding problem.
I'm going to play with it a little more today, and if I don't get anywhere pretty quick, I'll pull the master off for a look-see and bench bleed.
Hey guys, Thanks for the all input.

[RICH MUISE]

I'm finally gaining some pedal. Two more hours this morning, alot of back and forth, but the air is finally diminishing, and as I said I've got some pedal. I went front to back on the master a number of times, that seemed to help along with pumping the pedal.The master's front bleeder is at the top and all the way in front, so I'm guessing designed to vacate the area dgasman was mentioning with the master at a tilt. I'll give it a few more go-arounds then call it quits until the day I can road test it. Thanks alot for the inputs, I guess I just needed to spend a stupid amount of time on it. A few guys I talked to that said theirs bled fairly quickly were only replacing the master/hydroboost, not a whole new syatem. That's gotta make some difference.

[RICH MUISE]

I finally got adequate pedal after a few more hours of bleeding. I was told of the hydroboost was operating properly and everything was bled, I should get a "bump" in the brake pedal when I started the engine. I did.
On to the next episode.