Brake pedal goes to the floor

Is this clunk noise coming from under the dash near the brake pedal?
If so, see if there is maybe a loose or worn out brake pedal bushing or if the brake pedal rod is loose.
Here is a look at that brake pedal.

The noise appears to be in the pedal but did not exist until the brake job was done. I will check these things as you suggest but find it hard to understand how this is now all of a sudden happening after a complete brake job.

Thank you for your assistance.

If there is no air in the brake system then the only two other things that can cause this problem is a defective master or the rear shoes are out of adjustment. Here are a couple of guides to help you get the problem fixed.

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

and

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

and

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

The clunk you feel is normal when the master cylinder bottoms out.

Please let us know what happens.

Cheers, Ken

I have installed new calipers, pads, front brake lines, master cylinder, rear wheel cylinders, bled all the air from the system and have to pump the brake peddle several times to have any peddle with the engine off. As soon as I start the engine the peddle goes straight to the floor. I do not understand it, the brakes were fine before I installed the new calipers. Any suggestions?

It sounds like you may either still have air trapped in the brake system or you might have a bad brake booster. You replaced a lot of components so that is a lot of time for air to get into the system. If manually bleeding it does not work, try gravity bleeding the system. Just crack all the bleeder screws loose and let it be for about thirty minutes while making sure the reservoir does not run dry. Also make sure not to depress the brake pedal. As for the brake booster, make sure there are no leaks where the brake pedal rod goes into or where the master cylinder bolts into. Also make sure all applicable vacuum lines are attached.

Gravity bleeding did not help at all.

I am going to take it to a brake shop.
But thank you just the same.

Might also be the shoes need adjusting outward

See the whole deal in my link (more towards the end)

https://www.2carpros.com/questions/1998-ford-f-150-cant-get-brakes-bleed

Return with a grin!

The Medic

Brakes problem
1997 Ford F150 6 cyl Four Wheel Drive Manual 170000 miles

I changed the right front caliper on my 97 F-150. Every thing was working correctly prior to the change, besides the caliper hanging up. I installed the new caliper and it bled fine. However, after a min of sitting the peddle goes to the floor. You can pump them up in the pumps but then start the ignition and the peddle goes to the floor again. Any thoughts?

Hi unplugged_in_mn. Welcome to the forum. What does "You can pump them up in the pumps" mean? Let's hope there is still air trapped in the line. A quick fix, now that the caliper is pumped up and applied is to use a flat blade screwdriver to pry the piston back into the caliper to push the fluid back up to the reservoir. That will wash any air up there too.

A fairly common problem is caused by pedal-bleeding if the pedal is pressed all the way to the floor. Corrosion and debris build up in the bottom halves of the bores in the master cylinder where the lip seals don't normally travel. By pushing the pedal to the floor, the lip seals get torn on that debris. I always instructed my students to pretend there was a block of wood under the pedal and to never push it more than half way to the floor. Still, every year I had someone wreck a master cylinder. Typically you will notice the pedal sinking slowly to the floor when you hold steady pressure on it if the seals are ripped. In most cases a rebuilt master cylinder actually costs less than the rebuild kit that lets you do it yourself.

Caradiodoc

Brakes problem
1997 Ford F150 Four Wheel Drive Automatic

When we turn the wheel to the left the brake pedal sinks all the way to the floor as if it has no brakes, when we turn to the right it does not do that.

Check the front wheel bearings. If a bearing is loose it will rock in and cause the caliper to compress and then you will need to pump pedal to get it to come back out

Brakes problem
1998 Ford F150 V8 Two Wheel Drive Automatic 198K miles

A couple of months ago, I replace the calipers and pads on the front of my F150. I notice that the truck seemed to be dragging and that the front rims were really warm. Someone suggested that I should replace the short brake lines that connect the medal tubing to the calipers, which I did. At that point I started to bleed the system (with the car running) and noticed that the brake peddle went to the floor, but I tried to bleed the system with no change. When the truck is off you can pump the brake and it firms up a little. After talking to the parts guy, he stated that it was the Brake Cylinder. So with a little help and bench bleeding the new Brake Cylinder, I put it on the truck only to find that it didn't fix the issue. Now some people say it might be the Brake Booster! Please help!

See my profile.A manual would probably be very useful.
My neighbor has a chevy trk (LOWER CASE ON PURPOSE) his REPAIR MANUAL said something about bleeding some jct block, to the best of my recollection.

Have you explored this sites HOW TO STUFF. Maybe even explore old POSTS on down the line from yours.

I would think that if the booster was muffing up, the brakes would be stiffer.

I bench bleed. Installed on vehicle. Its whole lots EZer.W/buddy pumping the brake.

I hold 2 "rubber" bleed lines in the resevoirs (1-ea. Compartment)

I slightly squeeze them as pedal goes down (pal slowly pushes, and informs me as to his position, (halfway. FLOOR !). Rubber lines must always be SUBMERGED IN THE BRAKE JUICE !

When he is MMs from floor, I pinch the lines off, LIKE A CHECK-VALVE. Inform him to let pedal up. We repeat this. Over. Over again.

We do not want brake juice to suck back in rubber lines, all we want is the AIR to push out in only 1 direction only.

Careful !. Too hard or too fast pumping, w/ lines squeezed too tight will result in rubber lines BLOWING OFF of the plug/ adapters

I bleed furtherest wheel from Master Cylinder. Stepping my way back to the closest.

Insure you are pumping 5-6 times (or to get as stiff of a pedal as possible)

HOLDING then pushing slowly on pedal, while cracking the bleeder slightly and closing bleeders on wheel cyl. MMs prior to pedal hitting floor.

We usually Holler : PUMPING. HOLDING. And just before contact. FLOOR.I say, OK or PUMP IT UP, when bleeder is shut.

Not letting off pedal until bleeder is FULLY SHUT. COMMO with pal is CRITICAL !

NEVER EVER LET M.C. RUN DRY OR EVEN CLOSE DURING BLEEDING

Love, Turddog

Brakes problem
1998 Ford F150 V8 Two Wheel Drive Automatic 172000 miles

Replaced master cylinder twice and still no pedal. Bleed lines, etc. Have no brake fluid leak, still nothing. Benach bleed master cylinder before install, could I have damaged seasl during bleeding process? Pedal holds pressure after pumping brake several times with truck off, after starting pedal goes to floor. Could it be brake booster, booster check vale? Had issue with erratic idle when applying brakes before brakes went out. Only happened around town driving and almost at a complete stop idles would shoot up and almost stall, several cycles then idle would be fine? Thinking bad booster or booster check valve but how do I check?
Any help please?

Thanks.
Rob

What else was done to this brake system? How did the problem start?

Replaced front brake lines, calipers back on, bleed brakes, nada after that. Replaced master cylinder twice. Thinking that I might have damaged seals in master cylinder during bleeding process driving piston to far in. Possible. There r no leaks, not loosing brake fluid but no brakes at all. What do u think?
Thanks
rob

Check to see if maybe the calipers were put back on the wrong side of the truck. Look for the bleeders and see if they are at the highest point of the caliper. They can be switched and that would trap air at the top of the caliper that couldn't be removed.

Bleeder valves are on the bottom of the calipers. Is that the issue?
Could it be the speed control deactivation switch?
Thanks.

Yep, there's your problem. You put the calipers back on the wrong side of the car. The bleed has to be at the top or it will trap air. Switch sides and bleed over again and you should be fine.