2008 Rav4 bleeding brakes... air... air... and more air

[cabmandone]

What gives? I just got done doing new pads on all four corners. The drivers side front had worn the inside pad completely out. The piston on the caliper moved freely. I removed the slide pins and greased. I get everything back together, go for a test run, use my IR thermometer to check rotor temps and the front right is 250 where every other one was around 180. So I decide to bleed the brakes!

This is where the grief comes. I decide I'm going to replace the fluid so we do a full 4 corner bleed. I use a syringe to draw out most of the old fluid from the reservoir. I fill the reservoir with new fluid. I go rear right, rear left, front right, front left keeping the reservoir topped off before going to the next. Everything seems fine! I'll make a few more rounds until fluid runs clear! Rear right AIR... bleed until fluid. Same thing on the LR, RF, LF. Go back to the Right rear... AIR. So I decide to use the handy scan tool my brother loaned to to cycle the vales on this thing.
This system bleeds at the right side so I go right rear and get a lot of air when cycling the valve. Front right gets air as well. I go back and forth, filling the reservoir if it gets to the add line until no more air comes out. Then there's a four corner procedure. Then a four corner bleed again. I get to the 4 corner bleed... AIR

What gives? Do I have a master cylinder or drawing air? I've never opened the system other than to bleed brakes and never had the reservoir go below the minimum line. So how did I end up with all this air?

[slow&rusty]

I recommend trying a Motiv Power Bleeder

[cabmandone]

Originally Posted by slow&rusty

I recommend trying a Motiv Power Bleeder

I'm going to give that a try but I don't know how that's gonna stop the air. I've already dumped a little more than a quart of brake fluid through the system.

[biosurfer1]

hairline crack or split in a line somewhere?

[cabmandone]

Originally Posted by biosurfer1

hairline crack or split in a line somewhere?

I'd think if that were the case that when putting it under pressure I'd see some oil on the floor or the reservoir would end up being low. I'm going to check the lines from the MC to the valve body to see if there's any visible sign of leaking and maybe try to snug them up a bit. I'm almost completely at a loss on this. I'll be getting the adapter for my pressure bleeder this weekend so won't know how that goes till late Sunday or early Monday.

[Stovepipe]

Dual circuit brakes don't always bleed starting from the furthest away from the master cylinder. Read the manual and bleed in the specified order.

[cabmandone]

Originally Posted by Stovepipe

Dual circuit brakes don't always bleed starting from the furthest away from the master cylinder. Read the manual and bleed in the specified order.

I checked that and it's how Toyota recommends bleeding. There was a whole writeup about bleeding the lines and the ABS modulator valve (or whatever it's called)

[matthewb0051]

I either missed it or you didn't specify what you are using to bleed: motive? vacuum bleed at caliper? or the old extra person pushing the foot down?

I've had issues with vacuum bleed as it sometimes draws in air at the nipple. No idea how but the piece that goes over the nipple somehow pulls air in and it looks like you have tons of air when really you don't.

I was looking up recently Edd China's YouTube channel. I seem to recall he uses a Motive on one end and a vacuum on the other AT THE SAME TIME. He said something like neither being a 100% solution so using both gets the job done.

[cabmandone]

Originally Posted by matthewb0051

I either missed it or you didn't specify what you are using to bleed: motive? vacuum bleed at caliper? or the old extra person pushing the foot down?

I've had issues with vacuum bleed as it sometimes draws in air at the nipple. No idea how but the piece that goes over the nipple somehow pulls air in and it looks like you have tons of air when really you don't.

I was looking up recently Edd China's YouTube channel. I seem to recall he uses a Motive on one end and a vacuum on the other AT THE SAME TIME. He said something like neither being a 100% solution so using both gets the job done.

I'm doing the two person bleed. I'm going to stop by Summit Racing this weekend and snag a universal cap (because that's all motive offers for the yota) and try to do a pressure bleed. I've never experienced a brake bleed that was this stubborn.

[matthewb0051]

Originally Posted by cabmando

I've never experienced a brake bleed that was this stubborn.

I have but it was because I installed the caliper upside down on one car.

Then this:
And more recently after changing master cylinder on a new to us truck it just would not bleed. Took it to an indy Land Rover place. Guy told me that they even had trouble because it has SOOOO much air in the system.

Its my least favorite thing to do.

[cabmandone]

Originally Posted by matthewb0051

I have but it was because I installed the caliper upside down on one car.

Then this:
And more recently after changing master cylinder on a new to us truck it just would not bleed. Took it to an indy Land Rover place. Guy told me that they even had trouble because it has SOOOO much air in the system.

Its my least favorite thing to do.

Climbing my list of least favorite things to do RAPIDLY. Hopefully once I've got the adapter for the pressure bleeder things will get easier.

[Bob Kontak]

Do a gravity bleed on the right rear for 10 minutes after it starts to flow.

Tighten the bleeder. Wait five minutes and open the bleeder with no hose on it.

See what you get. Not a magic trick, just interested.

[beepbeep]

If ABS valve unit has been emptied, it might take a while to fill all the voids. Sometimes, you need to actuate it in certain order to remove all the voids.

[cabmandone]

Originally Posted by Bob Kontak

Do a gravity bleed on the right rear for 10 minutes after it starts to flow.

Tighten the bleeder. Wait five minutes and open the bleeder with no hose on it.

See what you get. Not a magic trick, just interested.

That was actually going to be my next move but I've opted to wait till I get my adapter for my pressure bleeder. Gonna snag one from Summit in Tallmadge while I'm up there enjoying some Octoberfest festivities!

Originally Posted by beepbeep

If ABS valve unit has been emptied, it might take a while to fill all the voids. Sometimes, you need to actuate it in certain order to remove all the voids.

I did that with the scan tool. It bleeds for 4 seconds then you restart the process for another 4 seconds if air was present. You continue like that until no more air is coming from the line.

[stealthn]

I would use the motive or some other way to pressurize the system and let it sit under pressure to see if there is a leak somewhere.

[cabmandone]

Originally Posted by stealthn

I would use the motive or some other way to pressurize the system and let it sit under pressure to see if there is a leak somewhere.

That's the plan once I have the adapter. Put it under pressure, put it up on the lift and start looking. If nothing visible, then start bleeding. I can't see there being a leak as I haven't put an ounce of brake fluid in the thing since I bought it several years ago. And when pumping the pedal there's nothing coming out under the vehicle. But I'm still gonna leak check just to be sure.

[matthewb0051]

FYI just make sure not to use too much pressure. I think about 15lbs is ok but higher can cause problems.

When I was doing my son's Land Rover Disco 2 I got it to pressure and was walking back to start bleeding the rear. Then I noticed fluid squirting out of the hard lines that ran down the frame to the rear calipers. Literally rusted thru and was opened up once I got some pressure in the system.

Must have been why the PO abandoned it on the street in Arlington VA. I bought it from the tow truck company.

[cabmandone]

I usually only pump up to about 10 or 12 pounds. I figure those little plastic reservoirs weren't built for pressure. When I helped my brother with is Buick the other week, the directions called for using 35lbs I told my brother "I don't think my cap will hold that kind of pressure. Let's just use 12" and it worked fine.

On the lines, beats the hell outta finding out the hard way like I did! 8000 lb skid loader on a trailer that weighs 3500 lbs in traffic in Columbus Ohio. Brake pedal goes to the floor. Front tires lock down. Trailer brakes... meh. Yeah that didn't end well. Thankfully no one was seriously injured. I'd rather find out in my shop with a lot of pressure than on the road!

[Jeff Hail]

The bleed process above is correct. Shuttling the pump solenoids does require a scan tool.

You mentioned one inner pad worn and no frozen pistons? You need to recalibrate the steering angle sensor zero point. That's the first thing we look at when we see that and no bent parts, no frozen pistons or sliders are present. Its also performed with a scan tool. Its a common diagnostic observation across the manufacturer board when a single pad is worn like that.

Its usually done on an alignment machine once all settings /values are in spec, final toe set and with wheel straight ahead connect your scan tool for the zero point reset. It can be done without the alignment machine to get a close zero point.

[Bob Kontak]

Originally Posted by Jeff Hail

You need to recalibrate the steering angle sensor zero point.

My 04 RAV was saying that.

I saw ways on youtube where you jumper this terminal to that in the OBD plug, watch this light flash this way and then that way and it's set.

Not saying this is the way to do it, just that there may be economy methods if you don't have a scanner.

I just acquired a 2010 Grand Caravan that has the issue. I don't think the code surfaces through routine OBDII codes. Believe it's ABS related.