Observations: Manual Brake Flush vs automated

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For a number of years, I have been a big advocate of one-man bleeder solutions and in particular, the Motive pressure bleeder. However, as I began to work on more cars, I found the Motive to be lacking coverage for exact-fit adapters on many common vehicles (i.e. Honda and Toyota). To solve this problem, I purchased a Mityvac with the brake bleeder kit, but soon discovered the flaws of vacuum bleeding - there was a 50/50 chance that I would introduce a small amount of air into the system.

Last weekend, I replaced the front struts on my father's Toyota minivan and had to bleed the brakes. (This is because the brake lines run through the struts, so you have to disconnect the lines in order to properly r/r the struts.) After bleeding the front brakes, I decided that it would be a good idea to also bleed the rear brakes so that the entire system had new fluid. With the help of an experienced friend, I only had to open/close the bleeder screw fewer than 10 times before new fluid was flowing out of the right/rear caliper. I was quite surprised by this, since I was always under the impression that the lines held a significant amount of fluid.

Judging from the amount of brake fluid I used to flush the rear calipers, I think I can flush a car with 1/2 to 2/3 quart of fluid. When using a vacuum or pressure bleeder, I often end up using 1.5 qt or more. I suspect that the manual method "forces/pulses" the fluid through, as opposed to gradual mixing that occurs when one uses a pressure bleeder. Lastly, I noticed that the brake pedal on my father's minivan was slightly firmer after the manual brake bleed - and the van had recently been flushed with a pressure bleeder.

So, I think I may be going back to manual bleeding. No hardware to buy and clean-up, less fluid used, and surprisingly quick and good results. Only issue is that you need a second person...

I guess the lesson learned here is that the "old-fashioned" method may sometimes work best, and is far less of a hassle than you were led to believe.
 
My challenge to you is to do a whole car completely with an 8 or 12 oz container from the dollar store.
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Indeed I still prefer to do it the old school way.

IF I happen to have someone to assist, I may do a motive bleed followed by the brake pedal. IMO. the brake pedal has always gotten a more firmer pedal
 
i've always done manual. and by sticking a short hose on the bleeder valve, I don't have to open/close it. just keep pumping the pedal, refilling the tank. no air gets pulled back in, as the hose has fluid in it. there is a slight fluid backwash when the pedal first starts to come back up, but not much.

25 years flushing brakes with a piece of hose in a coke bottle, going strong!

thanks for the comparo. it's an interesting observation.
 
I like to jam a stick/ ice scraper/ jack handle whatever between the pedal and the seat cushion. My permanent "helper". Crack a bleeder, that pressure keeps bubbles from coming in around the bleeder threads. My one-man technique.
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The reservoir on the previa is funky. I have two adapters and can do all my cars with the motive.

Mine is getting old enough that it is getting leaky... Happened to me this past weekend...

I thought going too far in pedal travel can be bad.

Two people in a lot of ways is easier, just because the setup time is less.

Ive not used them, but the checkvalve bleeders may be the best compromise, though Im not sure if they can suck air...
 
Old pump the pedal way is best. I use my 14 year old daughter as my assistant. She doesn't like it but who cares? Sit in the car and pump the pedal. It's so easy a caveman could do it. Then I buy her an iTunes card and she is happy.
 
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Originally Posted By: mechtech2
How in the world are you getting air in the system with vacuum bleeding?
And up to 50%!


I can only think that that air is getting sucked in through threads if the bleeder is opened too far. I highly doubt that vacuum bleeding actually introduces air into the system.

On the manual method, try bleeding with the car running and full vacuum assist. You will see even better results.
 
It's not possible for air getting sucked in through threads, even if the bleeder is opened very far while the Mityvac is in evacuate mode.

I use Mityvac to bleed the brake system of my cars more than twice for each car, no air whatsoever got into the brake system. The pedal felt firmer after each brake bleed.
 
Originally Posted By: eljefino
I like to jam a stick/ ice scraper/ jack handle whatever between the pedal and the seat cushion. My permanent "helper". Crack a bleeder, that pressure keeps bubbles from coming in around the bleeder threads. My one-man technique.
wink.gif



How exactly does that work? Would you have to repeatedly go back and reposition the stick after each "cycle?"
 
Originally Posted By: HTSS_TR
It's not possible for air getting sucked in through threads, even if the bleeder is opened very far while the Mityvac is in evacuate mode.



I've seen air leak back in through the bleeder threads. tightening them a smidge or dabbing some grease around stops it.
 
Originally Posted By: The Critic
Originally Posted By: eljefino
I like to jam a stick/ ice scraper/ jack handle whatever between the pedal and the seat cushion. My permanent "helper". Crack a bleeder, that pressure keeps bubbles from coming in around the bleeder threads. My one-man technique.
wink.gif



How exactly does that work? Would you have to repeatedly go back and reposition the stick after each "cycle?"


Yes! I use a piece if pipe personally, but you just go back and forth rack time you crack open the bleeder. Hang your clear hose in a slight upward arch with a twisty tie and the air bubbles have no chance of getting back into the system.
 
I use a mityvak vacuum bleeder and never have problems with air getting in the system. I always take most of the old fluid out of the master cylinder with a turky baster and add new fluid so it doesn't take as long to get clean fluid through the lines.

I just replaced the pads and rotors on all four wheels on my 2004 Monte Carlo and the brake pedal is very firm to the touch. I replaced all of the brake fluid with new as I described above.
 
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