While having several projects going at once on my Runner, I decided to change the brake pads, but took the caliper apart because I didn't know any better. I have taken the leads off of the battery for a different project. Do I need to have the key in the ignition, and to the "on" position to get the best results? I had my girlfriend press on the brake, while I loosened the bleeder valve. I heard some air gargle when I first loosened the valve each time. But no brake fluid came out. Is it as silly as taking the cap off of the master cylinder or is it more complex than that?
Question on Bleeding brake fluid
- Thread starter CapnRoo
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KB084RUNNER
New member
You need to have the key in the ignition and "on" to successfully bleed the brakes.
Depends upon the year of your 4Runner. If you have a 2004 or newer 4Runner, the booster pump will help you bleed the rear brakes if you're using the two-person brake bleeding method (one person at the bleeder and the other inside the vehicle pressing on the brake pedal). You can just have you assistant depress and hold the brake pedal while you turn the bleeder valve and let the pump do the rest. On the front brakes, your assistant will still have to pump and hold the brake pedal repeatedly while you open and close the bleeder valve because the booster pump will not cycle.
I am still having trouble. I had the car in the "on" position. I had my helper press and hold the brakes. The brake lights lit up, so I know it was pressed. But no fluid came out. We tried 3 or 4 times on each tire. I had plenty of fluid in the master cylinder. I tried it with the master cylinder cap off. Any suggestions?
cali_axela
New member
You have to make sure that you and your helper pressing the brake pedal are properly synchronizing your motions.
Step 0: Imagine how pressing down the brake pedal builds up a little pressure in the system when the system is sealed (all the bleeder valves are closed). If you open one of the bleeders before there's pressure built-up in the sealed system, nothing will come out of the caliper (and you may even introduce air into the system by accident by leaving it open without pressure coming out).
Step 1: Have your assistant pump the pedal several (4-5) times, and make sure they KEEP it held down on the last (5th) pump, to ensure there's plenty of pressure in there. Don't let them release the pedal yet, until you do the next step.
Step 2: While they're still holding the brake pedal down at the end of their 5th pump, IMMEDIATELY open the bleeder valve on the first (rear right) caliper. Since there's now a lot of pressure in the system, fluid should shoot out of it with a decent amount of pressure for just a couple seconds, and your helper will feel the brake pedal start falling towards the floor even further. Once the fluid stops coming out smoothly (you'll hear it sputter a little sometimes, and can just see the stream get much weaker) then CLOSE the bleeder valve immediately before the stream completely stops.
Step 3: Have the assistant pump the brake pedal once or twice more, and keep it held down again.
Step 4: While they're holding down the pedal again, repeat step 2.
Step 5: Repeat steps 2-4 until you see nice clean fluid coming out of the caliper. It will probably take more repetitions of this process for the first caliper since it's furthest from the cylinder.
Step 6: Top off the brake fluid reservoir with clean new brake fluid before moving onto the next caliper. You don't ever want the reservoir to go too far below the "min" line, allowing air to get in through there if it goes empty would not be fun.
Repeat this process (steps 2-6) for all 4 calipers -- the front ones should only take a few repetitions of the process, compared to several repetitions for the rear calipers.
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The easy way to ensure that you never get air into the system while bleeding the brakes is to attach a hose over the bleeder and put the other end into a jar of brake fluid. That way, if you do mess up with your timing, no air can get in.
After some trials and tribulations, I have concluded.
1. I had the caliper off for almost a week, so there is quite a bit of air in there.
2. I am just bleeding the front 2 brake lines. I started to have some sputter of fluids on the drivers side. I still have nothing on the passenger side. However, I was by myself, and was using a brick to hold the brake pedal down. But during the process of this, I was making progress, because the pedal was becoming less and less spongy, which means more and more fluid was getting to the correct place.
3. If I am still without my helper tomorrow, I will try the hose technique.
1. I had the caliper off for almost a week, so there is quite a bit of air in there.
2. I am just bleeding the front 2 brake lines. I started to have some sputter of fluids on the drivers side. I still have nothing on the passenger side. However, I was by myself, and was using a brick to hold the brake pedal down. But during the process of this, I was making progress, because the pedal was becoming less and less spongy, which means more and more fluid was getting to the correct place.
3. If I am still without my helper tomorrow, I will try the hose technique.
KB084RUNNER
New member
Dude: You NEED a helper...it can be a 12 year old kid or a 92 year old lady but someone needs to pump and hold down the pedal while you open and close the bleeder. You can gravity bleed some systems but the 4runner has an accumulator pump in the system and the key needs to be on. So a helper is best.
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cali_axela
New member
Yep... girlfriend/wife, kids, grandparents, that weird dude next door... they don't need any special skills or strength, just to be able to press the brake pedal on your command. I can't imagine how annoying it must be to try that process without a helper!
Okay, the booster pump will NOT pump when you bleed the front brakes. So you're going to need someone to press and hold the brake pedal down while you open and close the bleeder. You need to do this over and over again until you see no air bubbles in the tube that is going from the bleeder into the container of brake fluid. Make sure you use clear tubing so you can see the fluid and any bubbles that come out with it.
Do yourself a favor and search YouTube for videos on how to bleed brakes. And if you come across a video where they just let the brake fluid shoot out of the bleeder, skip that video and go to the next one.
TechWrench
Senior Member
When you have lost that much fluid in the lines, I have found it much easier to use the gravity method to initially bleed most of the air out of the lines and calipers before going to the pressure method. Just make sure the fluid level is full in the master cylinder, and starting with the closest wheel, open bleeder. Gravity will allow slow flow of fluid down to caliper and will force most of air out of line and caliper. Just make sure to keep checking level in master cylinder so you don't run it empty. You can do this procedure by yourself. I use a hose on the bleeder to catch the runoff in a bottle so as not to have fluid all over the place. When the fluid appears to run clear with no obvious air bubbles, move on to the next wheel until they are all done. Then I go back to using a helper to fine tune the bleed. Works every time for me. Also, make sure the bleeders are all clear, no obstructions.
You will need to bleed all 4 lines, even though you had just the front calipers off.
FWIW, you can vacuum bleed the 4R with the ignition off; haven't bothered to try bleeding with ignition on. I've heard that AZ/AA offer vacuum bleeders as part of their rent-a-tool programs...might be an option for CapnRoo to check on. I just use a MityVac kit that I picked up for $30ish several years ago.
Since vacuum bleeding works, I would assume something like a Motive power bleeder would also work with ignition off (pretty sure I've seen posts from owners who've done it). One can find DIY instructions for building your own Motive clone around the 'net, but I think you'll end up spending as much in parts as a MityVac kit would cost.
-Brent
ive bled all 4 and i still have a squishy pedal. ...i think air came in through the empty reservoir
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Ghostrider
Registered User
Has anyone tried a Motive on the 4th or 5th gen? It worked great on my 2001 and I am upgrading to a new one soon.
