Brake Pedal Goes to the Floor

First time 4Runner owner. I just picked up a pretty cheap 1997 SR5 4x4, with a 3" lift. It's gonna be a trail rig. Only real issue is the lack of brakes. I checked for puddles and leaks, but didn't see any fluid. I can hear what I think is a slight vacuum leak, which might explain poor brake performance, but the pedal goes straight to the floor. I can pump the brakes, and feel some stiffness, but it fades within a second.

Is this a badly leaking brake master cylinder? The fluid is almost engine oil colored.

 

First things first, Few things to check off the list. Have you checked the fluid level and ensured the entire brake system is bled properly?

Any leaks at the rear of the master cylinder at the booster mounting points?

 

Level looked fine, but it didn’t even occur to me that someone might’ve botched a brake job so bad the pedal went to the floor. I’ll check it tonight. Thanks!

 

as they say in the old dodge commercial

THAT CANT BE GOOD

 

There was a previous thread that indicated the rubber brake lines are a probable source of weak brakes.

https://www.amazon.com/dp/B0031HJNRK?ref=ppx_yo2ov_dt_b_product_details is the back line and
https://www.amazon.com/dp/B0130X8XIE?ref=ppx_yo2ov_dt_b_product_details is the set for the fronts.

I have both sitting on the bench right now waiting for a break in work to install. Another item to check is the adjustment of the
rear brake drums. Too loose on the adjustment and you will lose all your pedal.

 

This sounds very much like a situation I had with my 87 MR2 which turned out to be a bad master cylinder.

If I eased into the brakes, they would go straight to the floor. If I pumped them, or hit them suddenly, I could get some pressure. I could usually stop the vehicle by continuing to pump the brakes , but as soon as you stopped pumping, they would go to the floor.

As mentioned above, It's worth trying to bleed all of the brakes to see if there's just air in the lines.

 

Finally took the day off and still got rained on. I replaced the master cylinder just because the old one was full of engine oil colored fluid. While bleeding the brakes, I found lots of air (and oil colored brake fluid) and a pinhole leak at the front driver side wheel (the one you bleed last). Guessing the line split at the bend and just gave way.

hoping I can bend up a new one tomorrow that won’t split. Should that be 8 or 12 inches? Mine is pretty mangled.

 

Took my rig out today since I had it fixed at the local shop. They said a line was loose. Okay. Sure. Looked rusted through to me, but I’m just a hobbyist.

Got to the upholstery shop. Agreed upon a price to start tomorrow. On the way back, the brakes felt weak. Then the pedal went to the floor again.

Barely managed to get it into a parking spot. Got it towed back to the shop. Hoping they fix it for free, since they said it seemed fine.

Driving a rig with no brakes in midday traffic isn’t what I’d call fun.

 

What did it end up being?

 

Driver side front brake line was split at the bend and they replaced it for free. Apparently when they tightened it, it squeezed it together enough to hold pressure. They probably grabbed it at the bend with channel locks to turn the nut so no immediate leak. Couple of brakes later it felt like it was leaking again, so I was ready for it to go. Haven’t driven the rig since. Been too busy.