Proper method to change your brake fluid?

[Jetronic]

Originally Posted By: Doublehaul
Hate to say it guys...but I've never "changed" brake fluid...ive also never had an ABS or MC failure....and i keep cars a long time! Only time i remove fluid is if changing a brake line or a caliper etc and even then its only enough to get the air out.


I change brake fluid, and never had to change a caliper, or rebuild one... but not necessarily every 2 years.

 

[Lapham3]

It's funny=40-50 years ago in the RWD days we were repacking front end wheel bearings as 'routine maintenance' all the time and never thought about changing brake fluid. Now we are changing brake fluid. Myself, I'll gravity bleed some when changing pads/shoes, but that's about it. I still have some 'old iron' and I don't repack those front bearings anymore, just a spin and shake when the car's up for something else-never had one go bad yet. Better go find some wood to knock

 

[tig1]

I turkey baster mine every engine oil change. I also do that with the PS pump. Has worked well for me.

 

[dk1604]

Originally Posted By: HTSS_TR
Originally Posted By: Colt45ws
That's bizarre. Ive done the Mityvac for years before I bought the pressure bleeder and it was always a disaster. The hoses would fall off the bleeder if I looked them wrong. It was always a mess and took 10 minutes to do one wheel.

You're right.

Similar tools and totally difference results.

I use the hose that came with Motive power bleeder. When I hook up the hose to bleeder valve I twisted it 180 degree clockwise so that when I loosen the bleeder valve it is straight with the adapter.

The rears took about 2 minutes each, the fronts were about 1 minute each with 4 pumps on the extractor. I can speed up with few more pumps, but I took my time to do it right and a little slow is better so that the reservoir didn't get emptied.

One thing you and I are similar is we need 1 quart to bleed 4 wheels.

PS Trav, a very good mechanic, uses similar fluid extractor to bleed brake too.


I wonder if some of the different results comes from people using different tools. When I first read "Mityvac" I assumed you were using one of the small pistol style hand pump tools but then I googled a picture of the Mityvac 7201 and realized that is a completely different beast. I can see that working MUCH better than the pistol style hand pumps.

 

[supton]

Originally Posted By: tig1
I turkey baster mine every engine oil change. I also do that with the PS pump. Has worked well for me.


Brake fluid doesn't circulate, so are you assuming that moisture gets into the system only from the vent on the master cylinder?

 

[WellOiled]

Originally Posted By: Ed_Flecko
Originally Posted By: WobblyElvis
Originally Posted By: Doublehaul
Hate to say it guys...but I've never "changed" brake fluid...ive also never had an ABS or MC failure....and i keep cars a long time! Only time i remove fluid is if changing a brake line or a caliper etc and even then its only enough to get the air out.


+1
GM does not recommend changing brake fluid. Why would I? Never had a problem with the brake fluid. I don't change the air in my tires either.


The alcohol in brkae fluid is hygroscopic, so it absorbs moisture from its surroundings. The problem with moisture in brake fluid is that it causes corrosion. Moisture in brake fluid begins to attack the metal in the brake system. Some modern brake systems are comprised of aluminum, which a highly reactive metal. Oxygen in the absorbed moisture combines with aluminum to form aluminum oxide (think: aluminum oxide sandpaper). This damages the metal components. Once the surface finish of hydraulic cylinders are corroded, they begin to leak and must be replaced.

At least this is my understanding.

Ed


+1
Ed is right about this. Some manufacturers use cheaper materials in the brake lines. For those vehicles, an annual brake fluid flush is in order. I recently paid $70 for a flush and bleed. Come to find out they used a turkey baster and called it a day. I made a one man bleeder and did a bleed with plenty of fluid. You would not believe how much junk came out of those lines. I would rather do frequent flushes on this vehicle than to have a wheel cylinder lock up.

I did not have good luck with the little Mighty Vac. The air will just go around the bleed screws. I will do the pressure can next time so I can do a better job on the ABS motor.

 

[circuitsmith]

Originally Posted By: supton
Brake fluid doesn't circulate


There's this thing called diffusion.
A liquid can be standing still on a macroscopic scale, but at room temperature the molecules are moving around in random directions and bouncing off each other.
It's a slow process but it's happening 24-7; and a bit of contaminant can eventually travel a long distance.

The same applies to that little air vent hole.

 

[Colt45ws]

Originally Posted By: dk1604
Originally Posted By: HTSS_TR
Originally Posted By: Colt45ws
That's bizarre. Ive done the Mityvac for years before I bought the pressure bleeder and it was always a disaster. The hoses would fall off the bleeder if I looked them wrong. It was always a mess and took 10 minutes to do one wheel.

You're right.

Similar tools and totally difference results.

I use the hose that came with Motive power bleeder. When I hook up the hose to bleeder valve I twisted it 180 degree clockwise so that when I loosen the bleeder valve it is straight with the adapter.

The rears took about 2 minutes each, the fronts were about 1 minute each with 4 pumps on the extractor. I can speed up with few more pumps, but I took my time to do it right and a little slow is better so that the reservoir didn't get emptied.

One thing you and I are similar is we need 1 quart to bleed 4 wheels.

PS Trav, a very good mechanic, uses similar fluid extractor to bleed brake too.


I wonder if some of the different results comes from people using different tools. When I first read "Mityvac" I assumed you were using one of the small pistol style hand pump tools but then I googled a picture of the Mityvac 7201 and realized that is a completely different beast. I can see that working MUCH better than the pistol style hand pumps.

Oh wow. I never even bothered to google that number. You are right, that is a lot different than what I was thinking of with vacuum extraction.

 

[Ducked]

Originally Posted By: Ducked
Originally Posted By: Yup
Harbor Freight has them, too. I had a coupon and got mine for about $25.

http://www.northerntool.com/shop/tools/product_391590_391590?cm_mmc=Google-pla&utm_source=Google_PLA&utm_medium=Automotive%20%3E%20Brake%20Repair&utm_campaign=Mityvac&utm_content=33160&ci_src=17588969&ci_sku=33160&gclid=CNz2g-j9ucsCFUZrfgodhm0Flg


As far as I can tell, a syringe does the same thing for less than a dollar.


Correction 1 : If the poster on the testimonial site is correct in saying "I do wish it had the ability to provide pressure as well as vacuum." then a syringe does more (I've been cycling the fluid a bit to stir up crud/dislodge bubbles).

Correction 2 : I was thinking UK pound. A 60ml "enema" syringe and a bit of rubber tubing were 45NT from a medical supplies shop, which is about 1.4 US$

 

[demarpaint]

Originally Posted By: Kuato
Originally Posted By: Ed_Flecko
I have a 2 part question -

1.) Since brake fluid absorbs condensation from the atmosphere, how often should one change their brake fluid? Annually, or...???

2.) To flush all old fluid from the system, I'm thinking I'll buy a brand new turkey baster from the Dollar Store (so I know I'm not contaminating the system) and siphon out most (but not all) of the existing fluid from the reservoir. Then, I'll buy a brand new can of DOT 4 fluid, fill the reservoir and bleed the brakes, wheel by wheel (right-rear, left-rear, right-front and finally left-front), with the help of a friend.

Does this sound about right?

Thank you,
Ed


Your plan sounds great to me.

That's how I do it. Only I have a large syringe instead of a turkey baster, it just looks more impressive. LOL

 

[Yup]

Originally Posted By: dk1604
Originally Posted By: HTSS_TR
Originally Posted By: Colt45ws
That's bizarre. Ive done the Mityvac for years before I bought the pressure bleeder and it was always a disaster. The hoses would fall off the bleeder if I looked them wrong. It was always a mess and took 10 minutes to do one wheel.

You're right.

Similar tools and totally difference results.

I use the hose that came with Motive power bleeder. When I hook up the hose to bleeder valve I twisted it 180 degree clockwise so that when I loosen the bleeder valve it is straight with the adapter.

The rears took about 2 minutes each, the fronts were about 1 minute each with 4 pumps on the extractor. I can speed up with few more pumps, but I took my time to do it right and a little slow is better so that the reservoir didn't get emptied.

One thing you and I are similar is we need 1 quart to bleed 4 wheels.

PS Trav, a very good mechanic, uses similar fluid extractor to bleed brake too.


I wonder if some of the different results comes from people using different tools. When I first read "Mityvac" I assumed you were using one of the small pistol style hand pump tools but then I googled a picture of the Mityvac 7201 and realized that is a completely different beast. I can see that working MUCH better than the pistol style hand pumps.


I use the cheap pistol style one. Never had issues. Use it every year or two on my car, used it on my brothers after he out a new MC on, used it on my dads after a brake job. He never does routing maintenance like this and I pulled nasty fluid for a long time from his first bleeder. Not sure how people are saying the pistol style one doesn't work well. I've never had an issue. Also, a large syringe would do the same thing. I use the small syringe for filling my battery.

 

[cjcride]

The vacuum pump works good yet the tiny bubbles seeping in around the bleeder used to concern me.
When I went to the MityVac pressure bleed I never went back to the vacuum again.

 

[Lapham3]

To deal with leakage around the bleeder screws, I'd just grease them-helps for rusting and them getting frozen too.

 

[Ducked]

Originally Posted By: andyd
The Wheel cylinder bores are where the heavier crud ends up with the most water and rust and the lowest point. Right where the brakes are their hottest. That is the stuff you want to get rid of. The better stuff is what you sucked out of the MC using a turkey baster.


I wonder if there is in fact more water in the caliper/wheel cylinder fluid, or the discolouration is mostly due to sediment and a bit of wear from the moving parts.

I'd assumed the system mostly absorbed water vapour through the MC vent, so it got wet from the top down, but I don't know this for a fact.

Anyone with one of the gizmos have any data on this, or feel like getting some? I would but I'd bet you can't get them here.

 

[HTSS_TR]

For the ones who had concern about air bubble goes around the bleed screw back into the brake system, will you explain how air can go opposite direction of brake fluid which is sucked out of the brake system into a vacuum reservoir ?

This is similar to say that a leave on a river somehow goes opposite direction of the water flow.

I had been using my Mityvac 7201 on my cars for a total more than 10 times the last 15 years, never had a soft brake after all the bleeding. Actually the brakes seem to be firmer with new fluid and no air in the system.

I was a believer of specific for specific job, so I bought Motive pressure bleeder to do brake job for all cars, Mityvac 7201 to do oil change for E430. It turned out that Mityvac 7201 was a much better tool for brake job of my cars, especially for the rears of my E430 and LS400. I got rid of Motive pressure bleeder soon after.

Mityvac 7201 is great for ATF too. It can siphon ATF in my cars as much or more than drain by the plug or drop the pan. Why bother to raise the car and messing around with drain plug while you can just shove a hose into a tube to suck out old fluid and be done in less than 5-6 minutes ?

 

[dakota99]

While we're on the topic of brake fluid changing, if anyone needs the information for an eighth generation accord this is the procedure from the service manual. I've never had any problems doing it this way.

 

[WellOiled]

Originally Posted By: HTSS_TR
For the ones who had concern about air bubble goes around the bleed screw back into the brake system, will you explain how air can go opposite direction of brake fluid which is sucked out of the brake system into a vacuum reservoir ?

No concern here. I just could never get the Mityvac to pull a vacuum. Air would come in through the threads, through the bleed screw and through the pump. Mityvac could easily pull a vacuum on my thumb. I bought a new set of bleed screws and still had the same problem. The bottom of my truck is pretty rusty from all the salt they use in Kansas. I imagine the threads on the calipers and rear drums are pretty nasty. I had no grease to put on the bleed screw threads.

 

[WellOiled]

Dakota99 - That procedure would work well for a Honda Accord that comes with quality brake lines that do not corrode due to moisture in the fluid. The Ford Ranger has lower quality lines that do corrode over time. Therefore, I purge until the brake fluid runs clear and clean at each wheel. If you fashion a nice size catch bottle, you don't need a helper. Once you get maybe an inch of fluid in the catch bottle air can not come back up through the bleed screw. The only thing is you have to keep the reservoir topped up. I could get 6 to 8 strokes on the pedal before having to top up the reservoir.

There are lots of YouTube videos on this.

 

[Ducked]

Originally Posted By: HTSS_TR
For the ones who had concern about air bubble goes around the bleed screw back into the brake system, will you explain how air can go opposite direction of brake fluid which is sucked out of the brake system into a vacuum reservoir ?


That's probably not a significant risk, but if you're trying to remove air from the system by sucking it out, (as when refilling a drained system) the bubbles make it impossible to tell if/when you've succeeded.

Blowing works better for that, though there is allegedly a risk of everting seals in the master cylinder, and there's a real risk of pushing muck into it.

I've used as much pressure as I can generate with a syringe, which creates a noticable upwelling and turbulence in the master cylinder, and so far havn't experienced the first problem.

I cycle maybe 20 mls of fluid in-out a few times first to stir up and remove muck in the calipers/wheel cylinders/piping.

 

[Yup]

Originally Posted By: Ducked
Originally Posted By: HTSS_TR
For the ones who had concern about air bubble goes around the bleed screw back into the brake system, will you explain how air can go opposite direction of brake fluid which is sucked out of the brake system into a vacuum reservoir ?


That's probably not a significant risk, but if you're trying to remove air from the system by sucking it out, (as when refilling a drained system) the bubbles make it impossible to tell if/when you've succeeded.

Blowing works better for that, though there is allegedly a risk of everting seals in the master cylinder, and there's a real risk of pushing muck into it.

I've used as much pressure as I can generate with a syringe, which creates a noticable upwelling and turbulence in the master cylinder, and so far havn't experienced the first problem.

I cycle maybe 20 mls of fluid in-out a few times first to stir up and remove muck in the calipers/wheel cylinders/piping.


There are so many posts I could make right now that people would laugh over.