Brake bleeding problem

[fredkolias]

Installed new brakes front and rear (calipers, pads, rotors, drums, wheel cylinder, shoes). I bleed all the lines using a mitivac starting from rear pass, working towards front driver. Things seeem fine. I start the truck, depress the brake pedal...nothing! It goes right to the floor, no resistance.

So, when bleeding the brakes, should the truck be running? It seems when the truck is off, I get some resistance in the brake pedal. Once I turn on the ignition and start the truck running, no brakes. What's up with that? Thanks.

[JBH1989]

Bleed it with the engine off. For my own benefit, why did you replace the calipers?

Don't use the mityvac for anything but capturing brake fluid. If you have a little resistance in the pedal with the engine off, have someone work the pedal while you are underneath the car bleeding it. Pump the pedal until it's stiff, then open the bleeder. Instruct the pedal operator NOT to let the pedal bottom out, you can destroy the master cylinder pretty easily that way. Keep doing it that way until the pedal is nice and hard with the engine off. The booster removes the feeling from the pedal so you never know if it is properly bled--plus it's not an Isuzu so you're not going to blow the booster diaphragm by bleeding without the engine running.

[fredkolias]

Thanks. I didn't know about the booster. I'll give the pumping method a try. I like the mityvac for use on my motorcycles, but maybe it's not so good with trucks whose brake lines are much longer.

Also when using the mityvac, I notice lots or bubbles coming out along with the fluid, but always thought that was air being sucked in from around the bleeder nipple. When using a vacuum, is there anyway around that?

I replaced the calipers because they were practically seized due to rust. The pistons were not going back in until I got the truck up to speed. This is the third set of calipers and rotors, I'm at 123,000 miles. Also, my rotors were warped, the rear bell cranks were completly rusted and seized, and my drums and shoes were done. I replaced the rear wheel cylinders because one had a hole in it, which I may have done when taking the shoes off, so I replaced them both, cheap enough.

If/when I finally finish, I'll have new everything as far as brakes go. I went with the larger calipers too, I think from the 2005's. Had to cut that backing plate some, but not a problem. All the directions provided from this site were great.

I think one major factor in my front brakes going bad so often is because of the condition of my rear brakes. I''m not sure if my parking brake was actually working, I don't see how with the bell cranks rusted solid. Another culprit is the serious rusting on the underside of my truck. I know about the Toyota problems on these things, but I also blame the new kind of salt they use in the winters around here, and the cheaper steel used from over seas.

[Puffnstuff]

Yep bleeding the brakes is a two person job as jbh stated.

[MrBeanley]

Originally Posted by Puffnstuff

Yep bleeding the brakes is a two person job as jbh stated.

Actually, if you gravity bleed the brakes, you can do it solo. By "Gravity bleed", I simply mean you crack open one bleeder valve at a time and wait for the fluid to run out sans air bubbles. Its a bit slower, but much less messier and the only way to fly if you're doing the job alone.

One big warning, though: make sure you check the master cylinder frequently. If you let it empty out, you'll end up starting the whole bloody process over again from step one.

[kerykj]

2 words: Motive Bleeder

[JBH1989]

Originally Posted by fredkolias

Thanks. I didn't know about the booster. I'll give the pumping method a try. I like the mityvac for use on my motorcycles, but maybe it's not so good with trucks whose brake lines are much longer.

Also when using the mityvac, I notice lots or bubbles coming out along with the fluid, but always thought that was air being sucked in from around the bleeder nipple. When using a vacuum, is there anyway around that?

I replaced the calipers because they were practically seized due to rust. The pistons were not going back in until I got the truck up to speed. This is the third set of calipers and rotors, I'm at 123,000 miles. Also, my rotors were warped, the rear bell cranks were completly rusted and seized, and my drums and shoes were done. I replaced the rear wheel cylinders because one had a hole in it, which I may have done when taking the shoes off, so I replaced them both, cheap enough.

If/when I finally finish, I'll have new everything as far as brakes go. I went with the larger calipers too, I think from the 2005's. Had to cut that backing plate some, but not a problem. All the directions provided from this site were great.

I think one major factor in my front brakes going bad so often is because of the condition of my rear brakes. I''m not sure if my parking brake was actually working, I don't see how with the bell cranks rusted solid. Another culprit is the serious rusting on the underside of my truck. I know about the Toyota problems on these things, but I also blame the new kind of salt they use in the winters around here, and the cheaper steel used from over seas.

There will always be a lot of bubbles when using the mityvac and it's for the reason you stated. I use mine to capture fluid (pressure bleeder on the master cylinder) and I still get bubbles. You have to get a feel for it, you'll learn to know when the bubbles are coming from the bleeder threads or from air in the hydraulic system. Gravity bleeding works GREAT on NON-ABS vehicles and when doing clutches. On newer vehicles with ABS you really need to pressure bleed them or do it the 2-person way. The Motive Bleeder is great (pressure bleeder) but you have to get the right adapter, and since Toyota doesn't use a threaded cap, there is a chance you can blow the adapter off and get fluid everywhere.

I didn't see you were in the salt belt, it all makes sense now. I'd really hate to have to work on those trucks. I feel for you.

[fredkolias]

Well, I got my wife out there to help. She pumped, I bled. I was getting good solid fluid coming out. Except I'm still getting some bubbles on the rear passenger wheel. I started up the truck, and the brake pedal still goes to the floor (well, it would if I let it, but know not to). Could some bubbles from one wheel cause the pedal to be extremely soft, almost no resistance with the truck running?

I double checked for leaks, took at look at the rear wheel shoes to make sure they were adjusted right and weren't too loose. All seems fine.

I never gravity bled brakes, didn't know you could do that, for some reason I always imagined air going back into the system if left open without pressure. My tundra is a non-abs model, should I just crack that rear bleeder valve and keep it open for a few hours, keeping an eye of the master of course?

Thanks for the help, this is really freaking me out. I do most all my own maintenance on my cars, trucks, and motorcycles and never had this kind of problem. Normally bleeding brakes is an easy job.

[Boosted27606]

I have been told by a Honda tech to NEVER use a pressure bleeder for the brakes as you are forcing dirty fluid against the seal of the master cylinder and that will make it fail within a few month or weeks.

I use a vacuum bleeder at each wheel with no problem for the last 20 yrs. In fact, I bleed my brakes on the race cars before every race and always have a nice tight brake pedal. You don't want to start a race with a spongy pedal, trust me !.

[JBH1989]

If you have "dirty" fluid at the master cylinder you've got bigger problems.

It's normal for there to be nasty fluid on the caliper/cylinder side since they get heat cycled, but it (should) never be at the master cylinder. If you drain the master cylinder reservoir and fill it with clean fluid you should never have a problem. We haven't had a single comeback in the 20+ years our shop has been using pressure bleeding. I think that speaks for itself.

I have had vacuum bleeders let air back in the lines more often than not, causing a spongy pedal.

fred, did you replace any copper washers you touched (can't remember if Toyota uses banjo fittings)? Are all the connections nice and tight? So you are saying that no matter how much you bleed that rear corner it still has bubbles? Yes, one corner that has a lot of air will give a real spongy brake pedal. The last Tundra I bled (02 LTD V8 AC w/ABS) did have a slighty odd feel to the pedal after bleeding with the engine running. The engine has to remain off--starting it won't make the pedal hard again.

Gravity bleeding shouldn't take hours--first make sure the master cylinder is full and the truck is level. Crack that bleeder open just a hair, and sit back with a beer and wait for a couple drips of brake fluid on the ground. Once you see those drips, shut the valve and test the pedal. It should be good to go after that, but you could call your wife back out and bleed it manually once you have pressure. That's my procedure when replacing calipers, no sense wasting a bunch of time with two people (or when the other two guys are on a test drive or at lunch).

It'd be so much easier if I was next door, we'd have this thing on the road a long time ago. Don't you love how Toyota routed fluid to the front calipers? Japanese crack must be extra strong.

[fredkolias]

No banjo bolts, all the hoses screw right into the calipers and wheel cylinders. Doing the pump method, I went around the truck three times, rear pass, load prop thing, rear driver, front pass, front driver. After the first time around, all the lines were bubble free except the rear passenger. After the third time around, still getting bubbles from rear pass. Turned on the engine, brake pedal still goes to floor. Then I gave up.

I'll try to gravity bleed tomorrow (today), if that doesn't work, I may have to take the rear wheels and drums off again to see if something in there is not aligned properly. But it sure seemed right when I buttoned it up. I was moving things and they did what they were suppossed to. Except for testing the wheel cylinders, couldn't really do that from back there.

The problem must be at the rear though, the fronts were very straight forward, even bought fully loaded calipers because I didn't want to mess with pads and shims. However the rears have new shoes, wheel cylinders, and bell cranks. I had it stripped and cleaned down to the hub. I even went as far as painting the bell cranks with rustoleum to help prevent seizing again and greased everything real good. Also adjusted the parking brake cable because of the huge amount of slack, probably caused from pulling on it for several months without the bell cranks moving. I stretched the crap out of it.

To be continued...

[fredkolias]

I was just out there trying again. I took the drum off so I could see what's going on. The wheel cylinders are working fine. I dumped an entire small bottle of brake fluid thru that rear cylinder, and I'm still getting bubbles. Wife pumps the pedal, holds it in. When I crack the bleeder nipple, solid fluid comes out at first, but as the cylinder looses pressure and the shoes start going back in, bubbles start coming out, lots of them.

I'm wondering if that nipple is a problem. Because when I crack it, fluid will leak out from the threads. I tried the other rear, and getting the same problem, but less bubbles. The fronts seem fine, no sign of bubbles. But those are calipers, while the rears are new cylinders I just installed. Maybe they are crappy cylinders with crappy nipples?

When the truck is off, there is good pressure at the pedal and the pistons on the wheel cylinder work fine, but when the truck is running and no pressure at the pedal, the wheel cylinders only slightly move as the pedal is pushed.

Very frustrating.

[JBH1989]

What kind of wheel cylinders did you get? It's possible to get a bad one, especially if they are rebuilts. At this point I'd take it back and demand another one.

[kerykj]

FYI - I 1st used a Motive Bleeder on my 68 Corvette. The early Vette calipers are REALLY DIFFICULT to bleed. This tool is a God-send. Just my 2 cents...

[Triple BB]

Did you remember to bleed yer load proportioning valve while you were in the back...