Brake bleeding mystery. Help!

[BadBrad]

I have a 69 RR, 383, 11" drums, power booster, automatic, bone stock. I picked it up a few weeks ago and it had been sitting for 3-4 years. OK, the brakes shot.

Drums, shoes, wheel cylinders, all rubber hoses, new master cylinder, had the power booster rebuilt (fun getting that out and in), brass metering block cleaned, all steel lines flushed completely. OK, what am I missing?

Put it all together, bench bleed the master cylinder, 4 or 5 pumps and it get pressure and about 1/8 inch movement so it appears to be fine. Everything is tight, no leaks. Got some fluid to the right rear and finally to the left rear. Can't get the front wheel cylinders or steel lines for that matter to spit a bit of fluid. OK, Pull the lines from the M/C and get good pressure on the front fitting, next to nothing on the rear fitting. Pulled the M/C, pulled it apart and it looked ok but I got another one anyway. Bench bleed went fine. On the car, SOS, no fluid coming out of the rear fitting of the M/C. This is no way to impress my 16 year old kid I know what I am doing?!? Heck it works on Chevys and Fords!

BTW, I am using DOT5 since everything is new and/or flushed (steel lines and brass junction block.

It appears I am not getting pressure on the second fitting in the M/C but with 2 doing the same thing, I figure its me. Get plenty of actuator on the pedal, it even pops the fountain on the front lake in the M/C like it should.
A few bubbles on the back. IT BENCH BLEAD FINE (or is that bleeded?)

I think I have left no stone unturned? I assume I don't need to start the car and apply vacuum to the booster OR DO I?

Any advice would be appreciated!

 

[BadBrad]

BTW, I am bleeding using the old pump and hold, open the bleed valve, close it, pump some more. One post said I could ruin the M/C pumping all the way to the floor. Is that what I am doing wrong. Have I destroyed two M/C pumping 15 strokes and hold, bleed, close, pump again. The post was talking about disks on the front but I was giving the M/C no relief on the pumping (all the way to the floor)..... Is this an "ah ha" moment????

 

[scotts74birds]

I always use a mighty-vac these days. Try to borrow or rent one and apply vacuum to the bleeders and see if you can draw the fluid into them.

 

[fstfish66]

are you saying you are not, getting fluid pressure out of the master cylinder fittings it self ?? sounds like when you release the brake pedal,(not pushed to the floor) the pedal/push rod/master cyl is not returning all the way,keeping the orvice in the bottom of the master from opening and drawling fluid in to the main body,,,

since you have power brakes,,,its not as simple as just loosening up the 4 master mounting bolts to to see if thats the problem,,

some boosters have the small push rod attached to the booster,,,did you check to see if the ball on the end went in to the dimple in the master end ??? loosen up some thing just a tad and see if one of the push rods for some reason may be hanging up or a tad long,,

 

[BadBrad]

Thanks for the responses! I hooked up the vacuum pump and now have the wheel cylinders as full as I can get them. I put on a second M/C after bench bleeding. Before bolting it down, I had the kid push on the brake pedal and the M/C was pushed out by a half inch or so. The rod on the end of the power booster does have the ball end and extends about where it did before I had it rebuilt. I still don't get any pedal.

OK, pull the M/C again and did the bench bleed. I had strong squirting out of both fittings using the trusty screwdriver. Looked like plenty of pressure. Bolted it back on and no pedal.

Next step is to absolutely be sure I didn't screw up the actuator rods somehow but the darn thing is pushing on the M/C, maybe just not enough. The linkage to the brake pedal was pretty simple and I know the rod is moving. I would say about 3/4 inch into the M/C. That should be enough to get something on the pedal.

I am going to pull the M/C one more time and be sure its working on the bench. I am going over the linkage again. I was able to get a steady 10-15 pounds of vacuum on each wheel cylinder which indicates no leaks. Its gotta be the in pedal linkage as there is no place else that would cause the pressure problem.

Again, thanks for the suggestions!

 

[fstfish66]

sounds like you have fluid to squirt when bench bleedling it correct ???? im thinking when it is bolted up tight to the car that the push rod/brake pedal doesnt return all the way back (RELEASED ) to drawl fluid in to the master cyl body, if the pedal doesnt return all the way when the brakes are released fluid will not go in to the body of the master cyl to be pushed in to the brake lines,,

 

[Big Jim]

Just a question- when you bench bleed the m/c, are you using 2 short lines to dump the displaced fluid back into the reservoirs? If not, all you are doing is letting the m/c draw air back into itself when you release the piston. Have to keep the ends of the tubes sumberged in brake fluid or it's a waste of time and effort...JMHO

 

[fstfish66]

Just a question- when you bench bleed the m/c, are you using 2 short lines to dump the displaced fluid back into the reservoirs? If not, all you are doing is letting the m/c draw air back into itself when you release the piston. Have to keep the ends of the tubes sumberged in brake fluid or it's a waste of time and effort...JMHO

big jim,,thanks for jumping in, i hope he is bleeding the master correctly i never thought of that,,,

 

[BadBrad]

I guess Brad is more BAD.
Thanks for all the posts.
As I mentioned some time ago, I decided to check the linkage that I THOUGHT I had hooked up. I left the bottom linkage bolt out (DUH)!

This was my first replacement power booster. If you have ever done one, its NOT mechanic friendly. I thought I had all the linkage hoked up but I guess the blood rushed to my head upside down, legs over the seat, dodging the steering wheel, etc.......

The moral of the story is don't waste you guys time on duhs. However, all of you made me think real hard about the issue. My son found out, check yer work!

I appreciate your feedback! Got it all back together Sunday. Brakes work great but no power boost. Seems to have all the vacuum I need straight off the manifold, but the car is surging and perhaps the vacuum is not enough.

This car has not run for 4 or so years but it hit the road last Sunday. Doesn't run worth crap (surging?) but a fuel filter, fuel pressure measure, carb base gasket, etc. and I will let you know.

This board rocks with very knowledgeble members. I shall try to be more thorough before I call in the big guns next time.

Best Regards,
Not so BadBrad

 

[fstfish66]

well at least you got it to stop,,,big plus,,now get it running right,,,,good luck,,