Brake Flush Question

[John105]

There is no reason to flush the actuator as part of routine maintenance. That is a huge can of worms and is a very lengthy guided process.

True, on a BMW, it involves using the car's computer i.e. software, to actuate the ABS/DSC hydro pump. BMW states there is no other way to remove air, you can't simply drive on gravel or in the rain and slam on the brakes. The software actuates each channel separately, and the process is do go to all 4 calipers, one at a time. It basically doubles the job.

 

[paulo57509]

I've flushed/bleed the actuator (modulator) in the Legend. It's pretty straight forward once the principle of operation is understood (I got this from an NSX Forum). Instead of the Honda "black box" service tool, I put together my own black box that would momentarily run the pump. Once the fluid is under pressure, I could push another button and function the solenoid(s). This pushes the fluid thru the modulator.

I haven't yet been able to find a definitive explanation for the Toyota system (used on the Lexus) but I'm sure it's a variation of the same principle.

 

[The Critic]

I've flushed/bleed the actuator (modulator) in the Legend. It's pretty straight forward once the principle of operation is understood (I got this from an NSX Forum). Instead of the Honda "black box" service tool, I put together my own black box that would momentarily run the pump. Once the fluid is under pressure, I could push another button and function the solenoid(s). This pushes the fluid thru the modulator.

View attachment 184928

I haven't yet been able to find a definitive explanation for the Toyota system (used on the Lexus) but I'm sure it's a variation of the same principle.

Toyota actuators have been problematic in recent years. There’s a joke that if you run thru the guided function on the questionable ones, it may not work anymore once you’re done. The guided function for a full actuator bleed is quite extensive, plus you’ll also need to maintain battery voltage during this process.

 

[Lubener]

actually breaking the bleeder(loosening or when tightening)
Air in the calipers, air entering master cylinder if it gets to low
correct sequence to bleed(which wheel to start at first)
if you get any brake fluid on paint it will dissolve the paint.

are some of the main ones.

For as much as we complain about dealer prices.. brake flushes are almost worth the $$$.
Was just quoted on the 2020 ram
$180 and they clean and lube too.

Mechanics break bleeder screws too. You think they aren't going to pass the expense onto you for a new caliper?

 

[TiGeo]

Just fluid is all. Pressure breeders are nice for this but the 2 person method works fine too. I recommend removing anything you can from the reservoir and filling with fresh fluid before starting. No real magic to it. Just do it until the fluid runs clean out of the bleed hose at each caliper. At least with the modern VWs...they actually call for you to start at the front and work to the back so try to find out what the car you are working on calls for as it may not be furthest to closest.

 

[eljefino]

As the pads wear the distance needed to compress the pedal changes to compensate for thinner pads.

No it doesn't. One reason for the MC reservoir is to supply extra fluid that just hangs out down in the caliper piston area to take up the slack from the worn pads.

Disc brakes are self-adjusting. With the foot off the brake pedal a tiny hole is opened that lets fluid trickle down (or up) from the reservoir to take up this slack.

 

[Sequoiasoon]

The only time I did anything different than a pressure bleed or a 2 person full flush was when there was just crap on bottom of reservoir. One screw holds it in place on my cars. I removed it so I could "shake" it with clean fluid and then spray out with brake cleaner. New fluid "shake/drain" after and then reinstall.

Lack of timely flushes prior there was just a lot of sediment.

 

[SHOZ]

No it doesn't. One reason for the MC reservoir is to supply extra fluid that just hangs out down in the caliper piston area to take up the slack from the worn pads.

Disc brakes are self-adjusting. With the foot off the brake pedal a tiny hole is opened that lets fluid trickle down (or up) from the reservoir to take up this slack.

Low brake fluid level light is often the first warning for worn pads for the uninformed.

 

[wings&wheels]

Another bit of advice; if you go the two-person route and do not use a pressure bleeder, and you should use the pressure bleeder, do not press the brake pedal much past it's normal motion. On a questionably maintained vehicle, you may have rust or pits in the m/c beyond the normal piston stroke and passing over these may harm the seals.

Motive makes a nice pressure bleeder and I'm in the flush every three years camp. Never had anything less than a proper pedal with careful pressure bleeding. Careful is key; do not introduce any air into the system. Also, silicone grease on the bleeder threads.

 

[Rand]

Mechanics break bleeder screws too. You think they aren't going to pass the expense onto you for a new caliper?

My advice was directed at the OP for specific reasons. I'm not scared of the brake bleeder.

 

[SHOZ]

My bleeder screw was so rusted no wrench would fit it. Original from 2008 and a winter car. I hit it with a MAP torch for about a minute then used a vise grips to break it free. Had a spare from somewhere.

If you open the bleeder and no fluid comes out, then keep it open and press the pedal a few times to get the fluid going. Always seems to be a problem on the front passenger side of my Accent.

 

[oilboy123]

My bleeder screw was so rusted no wrench would fit it. Original from 2008 and a winter car. I hit it with a MAP torch for about a minute then used a vise grips to break it free. Had a spare from somewhere.

If you open the bleeder and no fluid comes out, then keep it open and press the pedal a few times to get the fluid going. Always seems to be a problem on the front passenger side of my Accent.

That is how I get the fluid to start moving. Then it starts moving on its own by gravity.

 

[wtd]

I too have worked on hundreds of brake system and when I see one front caliper with pads at 5-6mill while the other side is at 2mill and then I glance at the brake fluid reservoir and see dark, green, and generally nasty brake fluid in there, I know EXACTLY why one caliper is sticking and why the owner now needs new brakes and possibly even a caliper plus a fluid flush.

Easily avoidable with a simple brake flush every few years or when new brakes are installed. Most shops don’t touch the flush and just push that nasty old fluid in the calipers BACK UP into the ABS system and call it done.

Surprisingly, that 3-4% moisture is enough to cause me to re-adjust my muscle memory on my clutch leg after flushing my brake fluid. New fluid now compresses differently and I need to relearn the clutch pedal because it now performs differently…. And I flush my brake fluid every few years on this car because it shares the brake reservoir with the clutch pedal.

Most uneven brake pad wear and caliper issues that contribute to that is because people don't lubricate the slide pins at all, or they don't use the correct lubricant on the pins.

 

[The Critic]

Most uneven brake pad wear and caliper issues that contribute to that is because people don't lubricate the slide pins at all, or they don't use the correct lubricant on the pins.

Not out here. 10 yr old slide pins still have plenty of grease on them.

 

[ARCOgraphite]

Not out here. 10 yr old slide pins still have plenty of grease on them.

True.
If the accordian boot over the pin is attached at both ends, that grease isn't going anywhere, though I could see how it might dry up from the lost heat from braking, and the lube does tend to migrate to it's little reservoir, I have lots of snow and slush here have stuck brakes often - but the pins glide fine. It's the brake pad locating ears rusting and hanging up in the caliper "keyways" - even though they have stainless steel shims over the keyways- the calipers also rust behind the shims binding the brakes - at least on Subaru designs I have been servicing that last couple decades in this slush and salt belt - Ken