Brake pedal to the floor

[hallj22]

So as I was pulling into my driveway the brake pedal went to the floor and I almost hit my own house. That will make your butt pucker up real quick. Needless to say my brakes are gone. I am having some issues figuring out what it is. Brakes are the one area that I don't have a lot of experience with. I have helped people before but never 100% on my own. Luckily for me I have a spare car to drive. I have read different threads but wanted to give a firsthand account of my problem. So, I will detail out what I have done and hopefully the smart people here can give me some guidance.

1997 SR-5 with 250K.

1. The fluid was halfway between minimum and full which is probably due to the front brakes needing to be changed. There is still a little room on the pads. New ones should be here Tuesday.
2. I did not find a leak on the front calipers or the back drums.
3. I do see any leaks anywhere else.
4. When car is off I can pump the brakes and they seem to pump up.
5. When car is on I get about 4 pumps before it goes to the floor and brakes are gone.

I am all ears for what the next steps should be in troubleshooting. Thanks in advance.

Jerm!

 

[RockyrT4R]

I've heard of the o-rings failing inside the master cylinder, or need new brakes, good luck

 

[nissanh]

How many miles in the runner? Year?

Remove rear brake drums and inspect the inside of the dust boot in the wheel cylinder.

 

[19963.4lsr5]

When that happens to me it's always been a rusted brake line. But you say no leaks. And it would be obvious if it rusted through.

How dark is your brake fluid?


Sent from my iPhone using Tapatalk

 

[4Reak Show]

If you don't have any external leaks, Internal master cylinder leak would be my thought. That replacement process depends on if you have the integral ABS unit vs a standard master cylinder.

Good luck

 

[hallj22]

It is a 1997 SR-5 with 250K. I checked out the wheel cylinders. I do not see anything that would make me think there is a leak. I was leaning towards the master cylinder as well. The color of the fluid is normal i suppose. It doesn't look like its rust colored.

 

[csp]

xwhatever it is on an internal master cylinder leak if there's no external leaks. Fluid is leaking past the seals inside the master instead of being pushed to the calipers and rear brake cylinders.

 

[nissanh]

Try to loosen the bolts holding the master pump to the brake booster (no need to remove the brake lines: just make about 2 mm gap between the pump and the booster). If you find a flow of fluid at the joint, then the masterpump is leaking.

Also check the front wheel bearings for free-play. I once struggled for months to find a leak in a hilux with a front solid axle. Same issue as yours but no leaks. Ended up replacing the spindle and problem solved.

 

[19963.4lsr5]

It is a 1997 SR-5 with 250K. I checked out the wheel cylinders. I do not see anything that would make me think there is a leak. I was leaning towards the master cylinder as well. The color of the fluid is normal i suppose. It doesn't look like its rust colored.

I've had a problem similar to yours on my Cummins and noticed the fluid was black from moisture. I purged out all the old nasty fluid and had normal feeling brakes. That was a long time ago, and now anytime I see it turning brown I purge it out.


Sent from my iPhone using Tapatalk

 

[T4R2014]

Master cylinder.


Sent from my iPhone using Tapatalk

 

[hallj22]

Thanks everyone for the suggestions. I will write back with my findings.

 

[hallj22]

Due to some other issues I am finally working on my toy today. Since its been years since I changed a master cylinder I have a basic question that I should know the answer to but don't. I pulled an off old broken gasket that was between the master cylinder and power booster. The new cylinder did not come with a gasket nor does it look like they sell one. It looks like you don't use a gasket? Is this right or should I make one out of some permatex?

 

[shoota]

Due to some other issues I am finally working on my toy today. Since its been years since I changed a master cylinder I have a basic question that I should know the answer to but don't. I pulled an off old broken gasket that was between the master cylinder and power booster. The new cylinder did not come with a gasket nor does it look like they sell one. It looks like you don't use a gasket? Is this right or should I make one out of some permatex?

When I installed mine I installed the new one without that gasket and everything is fine.

 

[AZBub]

So as I was pulling into my driveway the brake pedal went to the floor and I almost hit my own house. That will make your butt pucker up real quick. Needless to say my brakes are gone. I am having some issues figuring out what it is. Brakes are the one area that I don't have a lot of experience with. I have helped people before but never 100% on my own. Luckily for me I have a spare car to drive. I have read different threads but wanted to give a firsthand account of my problem. So, I will detail out what I have done and hopefully the smart people here can give me some guidance.

1997 SR-5 with 250K.

1. The fluid was halfway between minimum and full which is probably due to the front brakes needing to be changed. There is still a little room on the pads. New ones should be here Tuesday.
2. I did not find a leak on the front calipers or the back drums.
3. I do see any leaks anywhere else.
4. When car is off I can pump the brakes and they seem to pump up.
5. When car is on I get about 4 pumps before it goes to the floor and brakes are gone.

I am all ears for what the next steps should be in troubleshooting. Thanks in advance.

Jerm!

Start engine. Press brake pedal to floor and hold. Turn engine off. If there is a lot of pressure pushing back shortly after this point it "could" be brake booster. You can check the valve by pulling it off, cleaning with WD-40, and validating it is only allowing air one way as well.


I had a very similar problem and thought it was the MC and replaced it. Had same problem till I replaced booster (with a salvage part, cause boosters are stupid expensive for a vacuum actuated servo)

Sent from my iPad using Tapatalk

 

[hallj22]

I also found my passenger back wheel cylinder is leaking a touch as well. So better to change it now and not when it blows out....

 

[hallj22]

So im at a crossroads and have found some other things im not sure about. Hoping that I can detail everything without sounding crazy here since its late. After the brake pedal went to the floor I thought it was the master cylinder. Father in law was over same day and while I went back to work he looked over the yota. He found no leakage on the rear or front breaks. (Hindsight is 20/20. I should have checked it myself) The fluid was low but I thought it was master cylinder. After changing master cylinder, front breaks, and rotors I moved to the rear. After taking the drum off the passenger side I found a mess. It never dawned on me that it could be the axle seal. Considering the low brake fluid and the pedal going to the floor and having no breaks at all Im still leaning towards the wheel cylinder. After I took it off it basically came apart in 3 pieces. Any thoughts? Thanks all.

 

[frodiesel]

Axle seal leak and brake issue are two separate but important issues. Search adjusting rear bellcranks.

Does your parking brake work? Its the only way the rear brakes get adjusted

 

[hallj22]

The parking breaks work. Im struggling with getting the stupid spring back on the drums. Im ready to take a torch to the entire thing. HA

 

[frodiesel]

The parking breaks work. Im struggling with getting the stupid spring back on the drums. Im ready to take a torch to the entire thing. HA

I know your pain. I did it with gloves on to protect your hands, a set of vice grip on the spring and use a screwdriver to leverage it over. Put the vice grips straight on. Perpendicular to the spring arm.

 

[hallj22]

So I have figured out that I suck at bleeding brakes. I guess in all my years, bleeding brakes is one thing I either never did or slept while doing. I can not seem to get it right. I replaced the master cylinder without bench bleeding it first. It never crossed my mind. Then and only after attempting to bleed the brakes did I realize I forgot to do it. I read that you can bleed the master cylinder while its on the car just by pumping the brakes and all it really does is introduce more air in the lines. Anyone care to chime in on that one? IF that's the case I have introduced a load of air into the system.

Below is the steps I did in order. Please feel free to mumble under your breath of how elementary I am and then point out where I screwed up.

1. Replaced master cylinder. Forgot to bench bleed it
2. Replaced front rotors and brake pads
3. Replaced back bakes and wheel cylinders


1. Made sure fluid level in master cylinder is a tad more than needed.
2. Turned key to own state.
3. Started with passenger rear brake.
4. Attempted to bleed with vacuum pump. A fair amount came out but then it stopped completely.
5. I was stumped so I moved to the driver side rear and attempted to bleed it. Nothing seemed to come out.

At this point I am wondering if it is because the master Cylinder wasn't bled or I have other issues. Instead of wasting more time I thought I would ask the experts here...