What have I done? (Brake fluid change)

[Stu_Rock]

This has been bugging me all day. I think there must be some cars for which vacuum bleeding just does not work.

I am now thinking that the reason I couldn't vacuum bleed the rear brakes of my Peugeot is that the wheel cylinder or master cylinder seals allow air to enter the system when it is subjected to strong vacuum. I suspect the 08 Sonata is the same way.

Good luck with the pressure bleeder.

 

[Volvo_ST1]

Originally Posted By: glum
I just ordered a Motive pressure bleeder.



You can, even without an assistant, combine the pressure bleeder with brake pedal pumping action. You have enough time to crack the bleeder screw, hop in the car and push the pedal halfway down, get out and close the bleeder. On my car, using the pressure bleeder alone makes bleeding a slow process.

Make sure that you keep the bottle into which you bleed suspended a bit higher than the caliper. I place the bottle on a cardboard box.

I use a clear vinyl tube that fits snugly on the bleeder and that goes into the cut to size yorker tip of a small plastic bottle. Make sure the end of the bleeding hose is submerged in fresh brake fluid in the bottle, or it won't work.

Don't forget to rap on the caliper a few times during the bleeding process.

 

[crinkles]

Motive pressure bleeder was a big fail for me, lot of money wasted. It may be operator error. I had the toyota one that does not have a screw on cap but rather a rubber seal you need to tighten onto the reservoir, darn near cracked the plastic.

next time i will use a one man kit - it is a tube with a one-way valve (out) at the end.

Silly Question - if this kit is attached to the bleed screw, and i push the pedal, what makes the pedal rebound after the downstroke while i'm bleeding the brakes?

 

[glum]

Why would air leaking at the bleeder screws matter? Mityvac addresses this concern and says it is not a problem. The vacuum system is pulling fluid from the system out the bleeder. Air, if it gets past the threads, isn't going to go up into the system; it's going to come right out the bleeder screw with the fluid. How could it defy the flow of the fluid? Unless--as I mentioned I avoided--the vacuum was interrupted.

Originally Posted By: Volvo_ST1
Make sure that you keep the bottle into which you bleed suspended a bit higher than the caliper. I place the bottle on a cardboard box.

Why? It seems this would only make it harder for the fluid to come out and go into the evacuation container.

Originally Posted By: Volvo_ST1
Make sure the end of the bleeding hose is submerged in fresh brake fluid in the bottle, or it won't work.

I thought submerging the evac tube in brake fluid was just a precaution, to ensure that air doesn't go back in in case system pressure went down (i.e. the person lifted their foot before the bleeder screw was tightened, or if the pressure bleeder lost pressure, etc.). That and to enable viewing of emitted air bubbles.

I'm not "challenging" you; just trying to understand.

Originally Posted By: crinkles
Silly Question - if this kit is attached to the bleed screw, and i push the pedal, what makes the pedal rebound after the downstroke while i'm bleeding the brakes?

I think it would be the pedal spring.

A thought occurred to me. I feel so stupid about it that I hesitate to even mention it. Because I am in the habit of shaking everything before using it (I even shake motor oil containers), I may have shaken the brake fluid container before putting it in the MC. Maybe when I put it in it was loaded with air bubbles from having shaken it? If I knew that was the case, I'd never stop punching myself in the face!

 

[glum]

Originally Posted By: Volvo_ST1
You can, even without an assistant, combine the pressure bleeder with brake pedal pumping action. You have enough time to crack the bleeder screw, hop in the car and push the pedal halfway down, get out and close the bleeder.

I'd worry about too much pressure being in the system. The pressure bleeder plus the pressure from the pedal...? I don't know.

In any case, I now have the pressure bleeder. Next challenge: What pressure to set it to? It simply says to use manufacturer specs for brake system pressure. Yeah, that info must've fallen out of my wallet, because I don't have it.

 

[HTSS_TR]

If no leaks are found between the Bleeder and master cylinder reservoir, unscrew pump cap and add 1 quart of new brake fluid, tighten pump cap then pump the bleeder to 10-15 PSI, release the bleeder screw by 1/2-3/4 turns.

 

[Craig in Canada]

I'm watching this with interest to see how it turns out. You may have introduced air somewhere interesting either via the MC or in the ABS loops, perhaps in a way that's "unique" to your car too.

In general, every pressure/vacuum bleeder I've seen still recommends that the pedal be cycled/moved at least once during the bleeding of each wheel to ensure that bubbles aren't hiding anywhere.

It's also extremely important to note (and I haven't seen anyone else mention it) that you must limit the pedal travel to be within the "normal" swept area of the pedal other wise the MC seal can be shredded by areas of the MC never usually encountered. If you don't put a brick, 2x4 or whatever under the brake pedal to limit travel and you sweep it to the floor you may have created a very expensive problem. Or, you might get lucky and you've "never heard of this in x decades of wrenching on cars". It can go either way

 

[glum]

Good to know I have an audience! The pressure is on in more ways than one!

Neither Mityvac nor Motive mention pressing the brake pedal down as part of the operation. I'm not being argumentative, just, you know, saying.

A wrench has been thrown into my week but hopefully I can give this a second go by Friday. So it appears I wasted a king's ransom on overnight shipping for the bleeder.

Thank you again, HTSS_TR. I called Motive (before reading your reply) and that's what they advised. I wish their printed instructions said the same; as it is, they simply say to use the "level recommended in [the] vehicle service manual".

 

[glum]

Is there any point in pulling the fuse for the ABS unit during bleeding?

 

[wiswind]

I cannot see any point in pulling the ABS fuse during bleeding.

I have liked the "one man" bleeder method.....and they are CHEAP at most any auto part store, like AutoZone.

You connect the clear hose to the bleeder screw using one of the adaptors that come with the kit......usually a pointed plastic part that goes into the bleeder screw end.
Then you place the bottle at a location that is ABOVE the bleeder screw......and have the tube dressed UP to the bottle.....so that the fluid flows UP to the bottle.
This is important as this setup will have air bubbles wanting to rise UP and away from the bleeder screw.

Then you pump the brake pedal a couple of times......each time you release the brake pedal......some fluid will be pulled back into the caliper/wheel cylinder, but it will be brake fluid and not air going back in.

It only takes a SMALL bubble to make a BIG mushy out of your pedal.

 

[Volvo_ST1]

Originally Posted By: glum
Why would air leaking at the bleeder screws matter? Mityvac addresses this concern and says it is not a problem. The vacuum system is pulling fluid from the system out the bleeder. Air, if it gets past the threads, isn't going to go up into the system; it's going to come right out the bleeder screw with the fluid. How could it defy the flow of the fluid? Unless--as I mentioned I avoided--the vacuum was interrupted.


Why do you ask me question 1? Did I say something regarding "air leaking at the bleeder screws"?

If Mityvac can maintain lower than ambient pressure ("vacuum"), then no, no outside air can be drawn back into the caliper. If it supposedly works so great, why don't you learn how to properly use that method instead of turning to the pressure bleeder, which is apparently going to be a big problem also?

Originally Posted By: glum
Originally Posted By: Volvo_ST1
Make sure that you keep the bottle into which you bleed suspended a bit higher than the caliper. I place the bottle on a cardboard box.

Why? It seems this would only make it harder for the fluid to come out and go into the evacuation container.


This helps evacuate air bubbles.

Originally Posted By: glum
Originally Posted By: Volvo_ST1
Make sure the end of the bleeding hose is submerged in fresh brake fluid in the bottle, or it won't work.

I thought submerging the evac tube in brake fluid was just a precaution, to ensure that air doesn't go back in in case system pressure went down (i.e. the person lifted their foot before the bleeder screw was tightened, or if the pressure bleeder lost pressure, etc.). That and to enable viewing of emitted air bubbles.

I'm not "challenging" you; just trying to understand.


I guess you should just try it out, since seeing is believing.

Originally Posted By: glum


A thought occurred to me. I feel so stupid about it that I hesitate to even mention it. Because I am in the habit of shaking everything before using it (I even shake motor oil containers), I may have shaken the brake fluid container before putting it in the MC. Maybe when I put it in it was loaded with air bubbles from having shaken it? If I knew that was the case, I'd never stop punching myself in the face!


Yeah, you really should to pummel yourself.

 

[Volvo_ST1]

Originally Posted By: glum
Originally Posted By: Volvo_ST1
You can, even without an assistant, combine the pressure bleeder with brake pedal pumping action. You have enough time to crack the bleeder screw, hop in the car and push the pedal halfway down, get out and close the bleeder.

I'd worry about too much pressure being in the system. The pressure bleeder plus the pressure from the pedal...? I don't know.

In any case, I now have the pressure bleeder. Next challenge: What pressure to set it to? It simply says to use manufacturer specs for brake system pressure. Yeah, that info must've fallen out of my wallet, because I don't have it.


This is the point where I get annoyed. Have you even bothered reading the instructions that are printed on the bleeder? Do you have a repair manual for you car?

To address you concern regarding pressure, I pressurize the bleeder only to 12 psi. That's why I can afford to also GENTLY and with FEEL pump the brake pedal to get the fluid moving. I'm not going to go down into the garage to check the specs on the bleeder, but I believe it tops out at 20 psi. That's probably a lot higher pressure than required for most cars' brake systems. How much pressure your car's brake system can handle depends on many things, including age and fatigue. For all I know, at 15 psi the brake fluid reservoir will crack. I'm sure some stunt driver will hyper-inflate to 300 psi.

 

[crinkles]

http://tooltray.com/images/products/SXNVISIBLEED.jpg

 

[demarpaint]

Originally Posted By: Trav
Go back to the first one you started with and put a piece of plastic or rubber hose on the bleeder and let it hang in a container, open the bleeder and let it drip for a few minutes.

If it doesn't start dripping with the bleeder still open push the brake pedal down slowly halfway and let up, this will get it flowing.

Tap on the caliper with a rubber mallet lightly to remove any stuck air bubbles and close the bleeder screw.
Have an assistant push down the brake pedal keeping pressure on it while you loosen the bleeder, close the bleeder before letting the pedal up.
Do this 2 or 3 times then move on the next one, make sure to top off the MC as needed during this process.

You have air in the system. Once you get it squared away as mentioned ^^, next time gravity bleed the system and make sure the MC level stays topped up while doing it. It takes longer but in the end the chance of introducing air into the system is almost non-existant. JMO

 

[glum]

Originally Posted By: Volvo_ST1
Originally Posted By: glum
Why would air leaking at the bleeder screws matter?

Why do you ask me question 1? Did I say something regarding "air leaking at the bleeder screws"?

No, sorry, I wasn't asking you and didn't mean to seem like I was. Forum fail.

Originally Posted By: Volvo_ST1
Originally Posted By: glum
In any case, I now have the pressure bleeder. Next challenge: What pressure to set it to? It simply says to use manufacturer specs for brake system pressure.

This is the point where I get annoyed. Have you even bothered reading the instructions that are printed on the bleeder? Do you have a repair manual for you car?

I've read (and printed) them. No mention of pushing on the brake pedal. Have a Chilton manual but no mention of brake system pressure. In any case, I'm all set; no more questions from me to annoy you.

I've also figured out, with 90% certainty, what went wrong the first time I tried bleeding.

 

[Letter_K]

Originally Posted By: crinkles
http://tooltray.com/images/products/SXNVISIBLEED.jpg


I had one of those (different brand) when I worked at a auto-parts store in highschool. Had the same problems as the OP when I loosened the bleeder screws too much and air got in through the threads. Was a decnet one-man brake bleeder with a one-way check valve. Only fluid and air could come out, not go back into the system.

I was looking for another since mine is 15 years old and hasn't been used in 13 years. Wonder how it compares to the typical one man bleed that is in wiswind's post. Those type don't have a one-way check valve, right? Anyone know?

So Glum what do you think went wrong?

 

[glum]

I did a vacuum bleed. Again, I don't see any possible way for air to get into the system through the bleeder when doing it this way, unless vacuum is broken. Whatever my mistakes, opening the bleeders too far wasn't one of them.

I'll post this in hopes that it saves someone else from making this mistake...

Where I went wrong was in not keeping the master cylinder filled. "But ah... You friggin moron, you SAID you kept it topped off!" And I thought I did. I found out afterward that the screen Hyundai has under the MC cover works... Let's just say extremely well. So well that it really impedes the flow of brake fluid into the MC. So what I was doing is rushing to the MC, pouring a little brake fluid in, SEEING THE MC APPARENTLY FULL because the level was near the neck of the MC, then running back to the bleeder. But the MC wasn't full--the screen was just making it seem that way because of how slowly fluid drains from the screen into the actual reservoir. Maybe I was rushing more than I needed to, but I really did not want to lose vacuum at the bleeder.

Judge the fluid level from the side of the MC? The MC on my car is not translucent enough to easily tell how much brake fluid is in there, especially once it contains brand-new fluid, which is quite colorless. I still could probably have done this if I had kept a good light on the opposite side of the MC, but I did not realize it was an issue.

So there you have it. Maybe I'll post a follow-up with the final outcome, but I'd rather die than ask another question in this thread.

 

[WMSmotorhead]

My experience has showed that a Gravity bleed works easiest. and works well. We had one old dog of a car that the caliper came all apart and it lost most all of the fluid.. We replaced the broken one.. put a plastic bucket under that corner, cracked the bleeder... and waited what seemed to be an eternity... more like a minute or so... for the dripping to start. we followed suit on all corners allowing a little to drip at each spot. Once we were done they brakes felt.. "Not Bad". My father used to say that the brakes would bleed themselves a bit over time.. and that the last of the air bubbles will eek out on their own.. Our job was to get it to 95%.. and make it safe to drive. And we were gentle with braking for the next few days while the pads/rotors broke in. The pedals always went from moderately firm to very good. in just a few days.

 

[doitmyself]

Glum, most of us are here to learn and share. There is a learning curve for everything, and what you shared about the glitches in your specific car might be beneficial to someone in the future. Thanks.

While pressure bleeding works fine in my Caravan, it seemed to not to work well on my daughter's Escort. For some reason, pressure on the MC reservoir didn't produce good flow at the bleeder valves. This problem has been discussed here before....valving or something in the system interfering on some car models. Maybe voodoo?

With vacuum bleeding, I could "imagine" that air could be pulled into the caliper past a "too open/ungreased" bleeder and instead of being directly sucked back out, the air enters a "pocket" inside the caliper. Just a guess.

As always, what works well for one person doesn't always work for others. Thanks for sharing.

 

[KrisZ]

Quote:
So what I was doing is rushing to the MC, pouring a little brake fluid in, SEEING THE MC APPARENTLY FULL because the level was near the neck of the MC, then running back to the bleeder. But the MC wasn't full--the screen was just making it seem that way because of how slowly fluid drains from the screen into the actual reservoir. Maybe I was rushing more than I needed to, but I really did not want to lose vacuum at the bleeder.



You don't have to rush at all.

Simply tighten the bleeder screw before attending MC, make sure the MC is full, sometimes lightly tapping the MC reservoir helps to determine the fluid line as you will see ripples, then just go back, give the fluid evacuator few pumps and open the bleeder screw.

The fluid flow does not have to be continuous for an effective bleed.