Pinch them both off at the hoses with hose pinchers. release one and see if it does it still. If not put the pinch back on and release the other and see if it does it. Then you are isolating if the problem is in the front or rear circuit.
HELP Brake pedal goes to floor slowly
- Thread starter 2fpower
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Yes please double check other possibilities, I don’t want you to sink on the expensive Brake Booster and then not be the cause.
Seems like if it were the booster it would’ve showed symptoms while the master cylinder was capped off too.
you can also have similar symptoms if you have a caliper that is sticking a little bit, yes I know that you checked the calipers, but if one caliper is slow to put pressure on the pads you will get that sinking pedal until the pads make contact. I had a similar issue and the calipers were sticking, new calipers and no problem
I know you said "new" master cylinder, but as far as I know A1 Cardone does not produce new master cylinders for our trucks, just rebuild parts. The reason I point this out is I have had next to no luck with rebuilt master cylinders. Of the half dozen or so I have tried early in my wrenching days, more than half have done exactly as you describe out of the box.
There are only two ways a master cylinder can bypass fluid internally, either the seal on the piston is damaged, or there is a flaw in the bore of the master cylinder itself (wear, groove, gouge, etc). If it is a damaged seal, it would bypass fluid no matter where the piston of the MC is in its bore. But if there were damage to the bore, it would only bypass fluid when the piston is in than spot. When you capped the outlets, the pistons cannot move. So there is likely no damage to the seals. But when you have the brake system hooked up, the piston in the MC moves in to its bore to the spot where there is damage and the MC bypasses fluid.
Years ago I chased my tail trying to figure out exactly what you are experiencing. The symptoms pointed to a bad master cylinder, but I "knew" it was good because it was the first thing I replaced. I was wrong, the master cylinder was bad out of the box, and when I finally made up my mind that was the problem, the replacement fixed it immediately.
There are only two ways a master cylinder can bypass fluid internally, either the seal on the piston is damaged, or there is a flaw in the bore of the master cylinder itself (wear, groove, gouge, etc). If it is a damaged seal, it would bypass fluid no matter where the piston of the MC is in its bore. But if there were damage to the bore, it would only bypass fluid when the piston is in than spot. When you capped the outlets, the pistons cannot move. So there is likely no damage to the seals. But when you have the brake system hooked up, the piston in the MC moves in to its bore to the spot where there is damage and the MC bypasses fluid.
Years ago I chased my tail trying to figure out exactly what you are experiencing. The symptoms pointed to a bad master cylinder, but I "knew" it was good because it was the first thing I replaced. I was wrong, the master cylinder was bad out of the box, and when I finally made up my mind that was the problem, the replacement fixed it immediately.
make sure that you check your rear slider pins as well, that can also cause a long pedal travel if the pins are seized. the piston will have to push all the way out and youll also notice pad ware only on the inside
2fpower
SILVER Star
- Thread starter
- #29
no trophy awarded yet. here is what we did today.
first we swapped out front calipers for another used pair, that seemed to move fine when I used a c clamp to compress them.
No change
plugged at the master the rear side so only front side was open.
no gosh darn change
plugged the front and rear at the master.
Felt great!
swapped the rear driver side, so both rear calipers changed have been changed now.
unplugged the rear, (so the front is plugged), and bled the rear.
Felt pretty good. So from that, we are assuming that front is the issue.
noticed that some wetness under the black covering over a hard brake line that goes from master to the pass front, so cut off a foot of it, reflared and connected it to the T.
Made new hard brake lines for the driver front soft line to the same T. Since the abs is deleted, this actually removes about 5 feet of hard line. We also made new hard line from same T to the master and for the heck of it, swapped in a new T fitting.
NO FRIGGIN CHANGE. ARE YOU KIDDING ME>>>>>>>
At this point on the front circuit the only unchanged part is the hard line from the T to the pass side, then there is a 6 inch hard line from that line to the soft line. The calipers are used, and i have new ones that should come in tomorrow.
This is simple hydraulics. WHY??????
Also, we are on our 4th quart of brake fluid now if you are counting and causing me to wonder if I have a drinking problem.
first we swapped out front calipers for another used pair, that seemed to move fine when I used a c clamp to compress them.
No change
plugged at the master the rear side so only front side was open.
no gosh darn change
plugged the front and rear at the master.
Felt great!
swapped the rear driver side, so both rear calipers changed have been changed now.
unplugged the rear, (so the front is plugged), and bled the rear.
Felt pretty good. So from that, we are assuming that front is the issue.
noticed that some wetness under the black covering over a hard brake line that goes from master to the pass front, so cut off a foot of it, reflared and connected it to the T.
Made new hard brake lines for the driver front soft line to the same T. Since the abs is deleted, this actually removes about 5 feet of hard line. We also made new hard line from same T to the master and for the heck of it, swapped in a new T fitting.
NO FRIGGIN CHANGE. ARE YOU KIDDING ME>>>>>>>
At this point on the front circuit the only unchanged part is the hard line from the T to the pass side, then there is a 6 inch hard line from that line to the soft line. The calipers are used, and i have new ones that should come in tomorrow.
This is simple hydraulics. WHY??????
Also, we are on our 4th quart of brake fluid now if you are counting and causing me to wonder if I have a drinking problem.
2fpower
SILVER Star
- Thread starter
- #30
before I quit last night, I cleaned all parts of the car of brake fluid.. This morning, I went out started the car and let it go through and drop the pedal to the floor about 20 times. I hoped to be able to go and find where the fluid was going. Nothing. I traced every line. I even pulled the master to see if the fluid is going behind the master. Dry as a bone.
Current plan is to see if we can narrow down what side on the front circuit is the issue. My plan is to use that plug and block off one side at the T fitting off the master to see if we can figure out if it is left or right side... or if that even makes a difference.
Oh, tested for vacuum, came in very solid
Current plan is to see if we can narrow down what side on the front circuit is the issue. My plan is to use that plug and block off one side at the T fitting off the master to see if we can figure out if it is left or right side... or if that even makes a difference.
Oh, tested for vacuum, came in very solid
I went through this and I'm still fighting against mediocre brake performance.
Things I have done so far:
New booster
New Aisin master from Cruiser Outfitters
New extended braided lines from Man-a-Free
New soft lines at the calipers
New front calipers
ABS/LSPV delete
Lubed rear caliper slider pins
I got a set of new Hawk 100series pads for the front that I'm going to install this weekend
The biggest change for me was the ABS/LSPV delete, huge improvement but still not perfect.
Things I have done so far:
New booster
New Aisin master from Cruiser Outfitters
New extended braided lines from Man-a-Free
New soft lines at the calipers
New front calipers
ABS/LSPV delete
Lubed rear caliper slider pins
I got a set of new Hawk 100series pads for the front that I'm going to install this weekend
The biggest change for me was the ABS/LSPV delete, huge improvement but still not perfect.
MoJ
Moderator
(The frayed wire on the charcoal canister is making me nervous. Sorry not adding anything useful.)
I had a reman master fail immediately with the same symptoms. Replaced with Toyota and all was well. Also, have you tried using a power bleeder rather than the pump the pedal approach?
I had a reman master fail immediately with the same symptoms. Replaced with Toyota and all was well. Also, have you tried using a power bleeder rather than the pump the pedal approach?
thatcabledude
GOLD Star
How are you bleeding at the calipers? Two person, vacuum, pressure at the MC?
2fpower
SILVER Star
- Thread starter
- #35
Yes, we found two wires the mice got to there. On the list to replace along with power steering pump.
Not using a power bleeder. Two man/woman job.
Two person - old fashioned method. 4 pumps at master, hold, I bleed it out with clear plastic line. Do it multiple times until all air is out, and then a couple extra times to make sure. Brakes feel amazing when the car is not running.
One more thing... as I watched the fluid last night it seemed to all come out at the same pace at each corner. @StucknKS was doing the in car work and he said that all four corners feel when I opened the valve seemed the same.
thatcabledude
GOLD Star
I was having the same issue recently after swapping in new front calipers and axle to caliper lines. I was loosing hope. Brakes were fine before a swapped calipers, but the fluid was pretty old. I switched to using my home brew pump up garden sprayer with Motive Toyota MC cap eventually and pushed probably 4 quarts of brake fluid through. Eventually they were great. Not sure why it took so damn long.
2fpower
SILVER Star
- Thread starter
- #37
I was just reading on @musthave thread:
forum.ih8mud.com
I have another master coming in the mail -- number three now -- so will try that.
I'm at my absolute wits end- Fading Brake pedal despite best efforts
forum.ih8mud.com
I have another master coming in the mail -- number three now -- so will try that.
I'll admit this probably won't help, but I was having the exact same issue you are having. I ordered a master from parts geek, and 4 new calipers. I usually don't advocate throwing parts at the problem, but I needed to get up and running in a hurry. These parts completely fixed my issues.
Also, I bled my brakes using a vacuum pump.
Again, this isn't a solution, but its a data point for consideration. Feel free to contact me if you have any questions/ideas. I may have tried them already.
Also, I bled my brakes using a vacuum pump.
Again, this isn't a solution, but its a data point for consideration. Feel free to contact me if you have any questions/ideas. I may have tried them already.
2fpower
SILVER Star
- Thread starter
- #39
@thatcabledude "I switched to using my home brew pump up garden sprayer with Motive Toyota MC cap"
Guess it is time for me to build one of these..... can you point me in a direction?
Guess it is time for me to build one of these..... can you point me in a direction?
