Brake Flush: Motive Bleeder v.s. Mityvac MV7201

[bimmerdriver]

I have a mityvac mv7201 and their MVA7205 Brake Bleed Conversion Kit. I found it does not work effectively for single person bleeding. I've tried it on several vehicles including VW and MB. In all cases, it was necessary to have someone pressing the brake pedal to generate any reasonable flow rate.

When you think about it, it's not surprising that vacuum does not work. It's easier to generate more pressure differential using a pressure bleeder because the most possible vacuum is 1 atm.

 

[volodymyr]

Hello,

After being inspired by HTSS_TR's post about brake bleeding using Mityvac MV7201 and vacuum bleeding I've decided to give a try and post my feedback.

Before starting to talk about Mityvac MV7201 and vacuum bleeding I would like to talk about Mityvac MV6840 and pressure bleeding. In 2015 I've purchased an Mityvac MV6840 from Amazon (https://www.amazon.com/Mityvac-MV6840-Pr...9009&sr=1-8) and decided to try it on Peugeot 107 (2007) which is an European clone of Toyota Aygo.

After watching a couple of videos on youtube about Mityvac MV6840 I had an impression that the pressure bleeding process is safe and there is absolutely no way an air may enter the system. So, I've filled the device with 2 liters of DOT4 brake fluid, hooked up an adapter to master cylinder, pumped 15 psi of pressure and went to the rear wheel to bleed the caliper. After opening the bleeder I've waited like 30 seconds and I started to notice a bursts of air coming out of the bleeder !!!

I could not believe my eyes, so I closed the bleeder and went to the device to see what is wrong. I noticed that Mityvac MV6840 somehow was pumping air bubbles into the master cylinder and pushing the air under pressure via the brake lines.

I tried many things with Mityvac MV6840 to avoid having air bubles going into MC and eventually the only solution that worked for me was to:

1. Pump 15 psi of pressure and start noticing fluid going into MC

2. Bleed caliper for 5 second

3. Go to MC and see if bubles are being pushed.

4. If not, goto #2

5. If yes, release the pressure, goto#1

As you can imagine, doing all these things take enormous time, so I contacted Amazon, explained the problem and returned the device and I thought to solve the problem until brake fluid is due for replacement.

Two years later

I bought Mityvac MV7201 mainly for an engine oil change, and I tried it for brake fluid bleeding as well. I did not buy any special adapters, just found some tube that matches the size of the bleeders that are used on my car (Nissan Qashqai 4WD, 2010). My process was quite simple, I was doing the wheel replacement to put winter tires and each time I removed a wheel I also did the vacuum bleeding on that wheel. It was quite fast process - with around 5 pumps I was able to get a good vacuum that will result in a constant flow of brake fluid for like 5 minutes.

It was not too fast either, so I could not really miss a moment and get some air in MC, I was able to stay most of the time near MC and top up it in time. All in all, using vacuum bleeding and Mityvac MV7201 I achieved the following:

1. Less brake fluid used. If you use pressure bleeding you really need a lot of fluid in the pressure bleeder, like 1-2-3 liters

2. Less time used. It took me around 5 minutes per each caliper

3. No risk when over-pressurizing the MC and having a potential chance that it all can explode and you know, DOT4 fluid in your eyes is not the best thing

4. Somehow a cleaner job - no spills, etc

 

[DoubleWasp]

Vacuum always seems simple at first, but too many times we've encountered air leaks from the bleeders that necessitated attempting to put grease around the threads, only to have that fail to stop the leaks.

Attempting to do vacuum bleeding while using a scan tool to trigger ABS pumps and valves is a nightmare.

Bleeding a trailer using vacuum bleeding is also 10 kinds of awful.

Some systems will literally not vacuum bleed.....at all. None of my forklifts will.

Pressure bleeding requires working the adapter into place in a way that can be more difficult than it should be.

More different types of vehicles you have, the more adapters you are going to buy with pressure bleeding.

At the end of the day, results are ridiculously more consistent with pressure bleeding, so that's what we will continue to do.

 

[Smoqueed]

What I've done before is I've taken a large syringe, put a piece of rubber tubing over the tip of the syringe that I got from a cheap one man bleeder kit at autozone, smear some Silglyde around where the bleeder screw meets the caliper to prevent air from making it's way back in through the threads, popped the MC cap, and sucked fluid with the syringe. Not the most effective method as you have to close the bleeder, drain the syringe, hook it back up, and reopen the bleeder a few times, but it works

Originally Posted By: DoubleWasp
Vacuum always seems simple at first, but too many times we've encountered air leaks from the bleeders that necessitated attempting to put grease around the threads, only to have that fail to stop the leaks.

Attempting to do vacuum bleeding while using a scan tool to trigger ABS pumps and valves is a nightmare.

Bleeding a trailer using vacuum bleeding is also 10 kinds of awful.

Some systems will literally not vacuum bleed.....at all. None of my forklifts will.

Pressure bleeding requires working the adapter into place in a way that can be more difficult than it should be.

More different types of vehicles you have, the more adapters you are going to buy with pressure bleeding.

At the end of the day, results are ridiculously more consistent with pressure bleeding, so that's what we will continue to do.


I've been wanting to buy a pressure bleeder, but spending $60~ bucks + $30~ each for different adapters just seems too steep personally. But for some applications, it's probably a must.

 

[jrvn]

the best bleeding system is to take the vehicle to a service center that has a pressure bleeding machine such as a BG machine and pay them to do it right. I have tried all kinds of Do-it- yourself bleeding techniques along with Mightyvac, 2 man pump bleeding, jar with tube submerged etc etc. none were as succesfull as taking the vehicle to a place that uses a pressure bleeding machine and having a Tech that knows how to use it. using the machine allows the tech to do two important things getting out the old fluid/air and infusing new air free fluid into the vehicle, the rest of these techniques will not purge the air out of the brake system well enough to give a good pedal feel and positive braking performance. my advice is to take the vehicle to service every 30k miles and have the pros do it money well spent, when you finally have a good brake pedal not spongey mush.

 

[jrvn]

https://youtu.be/Jp5EgI5c6ws

 

[doitmyself]

For anyone to believe you, you will have to provide evidence that the shop machine somehow does the job better than a properly executed DIY method. Your logic seems to be that because you could not do a diy brake fluid exchange properly, the only way for everyone to get this done is to pay a shop to do it. It's kind of like saying that a shop can rotate your tires better than a DIYer.


Originally Posted By: jrvn
the best bleeding system is to take the vehicle to a service center that has a pressure bleeding machine such as a BG machine and pay them to do it right. I have tried all kinds of Do-it- yourself bleeding techniques along with Mightyvac, 2 man pump bleeding, jar with tube submerged etc etc. none were as succesfull as taking the vehicle to a place that uses a pressure bleeding machine and having a Tech that knows how to use it. using the machine allows the tech to do two important things getting out the old fluid/air and infusing new air free fluid into the vehicle, the rest of these techniques will not purge the air out of the brake system well enough to give a good pedal feel and positive braking performance. my advice is to take the vehicle to service every 30k miles and have the pros do it money well spent, when you finally have a good brake pedal not spongey mush.

 

[volodymyr]

Originally Posted By: doitmyself
It's kind of like saying that a shop can rotate your tires better than a DIYer.


+1

 

[jrvn]

Originally Posted By: doitmyself
For anyone to believe you, you will have to provide evidence that the shop machine somehow does the job better than a properly executed DIY method. Your logic seems to be that because you could not do a diy brake fluid exchange properly, the only way for everyone to get this done is to pay a shop to do it. It's kind of like saying that a shop can rotate your tires better than a DIYer.


Originally Posted By: jrvn
the best bleeding system is to take the vehicle to a service center that has a pressure bleeding machine such as a BG machine and pay them to do it right. I have tried all kinds of Do-it- yourself bleeding techniques along with Mightyvac, 2 man pump bleeding, jar with tube submerged etc etc. none were as succesfull as taking the vehicle to a place that uses a pressure bleeding machine and having a Tech that knows how to use it. using the machine allows the tech to do two important things getting out the old fluid/air and infusing new air free fluid into the vehicle, the rest of these techniques will not purge the air out of the brake system well enough to give a good pedal feel and positive braking performance. my advice is to take the vehicle to service every 30k miles and have the pros do it money well spent, when you finally have a good brake pedal not spongey mush.
no my evidence is that ive tried all the DIYer methods and none have worked as good as the BG pressure bleeder system it pushes fluid thru the MC and also suctions/vacuums the old fluid thru the nipple valves. so why waste time and money on MacGyver type reasoning and dollars on a hit or miss system when you can get a Grand slam at every 30k miles by paying a pro $100 and leave there having a firm pedal, instead of mushy pedal due to air escaping thru the bleeder threads and whatnot nonsense.

 

[volodymyr]

jrvn,

Originally Posted By: jrvn
so why waste time and money on MacGyver type reasoning and dollars on a hit or miss system when you can get a Grand slam at every 30k miles by paying a pro $100 and leave there having a firm pedal, instead of mushy pedal due to air escaping thru the bleeder threads and whatnot nonsense.


So, probably in the US this is the price. In some other parts of the world like in Switzerland an oil change + brake fluid bleeding is ~ 700 US dollars.

 

[jrvn]

 

[Ducked]

Originally Posted By: Smoqueed
What I've done before is I've taken a large syringe, put a piece of rubber tubing over the tip of the syringe that I got from a cheap one man bleeder kit at autozone, smear some Silglyde around where the bleeder screw meets the caliper to prevent air from making it's way back in through the threads, popped the MC cap, and sucked fluid with the syringe. Not the most effective method as you have to close the bleeder, drain the syringe, hook it back up, and reopen the bleeder a few times, but it works

Originally Posted By: DoubleWasp
Vacuum always seems simple at first, but too many times we've encountered air leaks from the bleeders that necessitated attempting to put grease around the threads, only to have that fail to stop the leaks.




I've been wanting to buy a pressure bleeder, but spending $60~ bucks + $30~ each for different adapters just seems too steep personally. But for some applications, it's probably a must.


I've had good results with an enema syringe. Can be used for pressure filling, vacuum bleeding, or both alternating, cycling fluid in and out. The last is very good at removing any stubborn bubbles without wasting a lot of brake fluid.

Sometimes air leaks in around the bleeder threads when vacuum bleeding but I don't find this to be much of a problem, since it goes with the flow/uphill and ends up in the syringe rather than in the braking system.

I should point out that its often claimed that pushing fluid upward through the system can evert master cylinder seals, and perhaps it can, but I've had no problems even though I used to apply as much pressure as I physically could.

I should also point out that I've never done this with an ABS system.

 

[speedlever]

Originally Posted By: jrvn
Originally Posted By: doitmyself
For anyone to believe you, you will have to provide evidence that the shop machine somehow does the job better than a properly executed DIY method. Your logic seems to be that because you could not do a diy brake fluid exchange properly, the only way for everyone to get this done is to pay a shop to do it. It's kind of like saying that a shop can rotate your tires better than a DIYer.


Originally Posted By: jrvn
the best bleeding system is to take the vehicle to a service center that has a pressure bleeding machine such as a BG machine and pay them to do it right. I have tried all kinds of Do-it- yourself bleeding techniques along with Mightyvac, 2 man pump bleeding, jar with tube submerged etc etc. none were as succesfull as taking the vehicle to a place that uses a pressure bleeding machine and having a Tech that knows how to use it. using the machine allows the tech to do two important things getting out the old fluid/air and infusing new air free fluid into the vehicle, the rest of these techniques will not purge the air out of the brake system well enough to give a good pedal feel and positive braking performance. my advice is to take the vehicle to service every 30k miles and have the pros do it money well spent, when you finally have a good brake pedal not spongey mush.
no my evidence is that ive tried all the DIYer methods and none have worked as good as the BG pressure bleeder system it pushes fluid thru the MC and also suctions/vacuums the old fluid thru the nipple valves. so why waste time and money on MacGyver type reasoning and dollars on a hit or miss system when you can get a Grand slam at every 30k miles by paying a pro $100 and leave there having a firm pedal, instead of mushy pedal due to air escaping thru the bleeder threads and whatnot nonsense.


Perhaps because when I do this myself, I don't have issues with mushy brake pedals? And save myself $129 or whatever a local shop will charge.

 

[jrvn]

Originally Posted By: speedlever
Originally Posted By: jrvn
Originally Posted By: doitmyself
For anyone to believe you, you will have to provide evidence that the shop machine somehow does the job better than a properly executed DIY method. Your logic seems to be that because you could not do a diy brake fluid exchange properly, the only way for everyone to get this done is to pay a shop to do it. It's kind of like saying that a shop can rotate your tires better than a DIYer.


Originally Posted By: jrvn
the best bleeding system is to take the vehicle to a service center that has a pressure bleeding machine such as a BG machine and pay them to do it right. I have tried all kinds of Do-it- yourself bleeding techniques along with Mightyvac, 2 man pump bleeding, jar with tube submerged etc etc. none were as succesfull as taking the vehicle to a place that uses a pressure bleeding machine and having a Tech that knows how to use it. using the machine allows the tech to do two important things getting out the old fluid/air and infusing new air free fluid into the vehicle, the rest of these techniques will not purge the air out of the brake system well enough to give a good pedal feel and positive braking performance. my advice is to take the vehicle to service every 30k miles and have the pros do it money well spent, when you finally have a good brake pedal not spongey mush.
no my evidence is that ive tried all the DIYer methods and none have worked as good as the BG pressure bleeder system it pushes fluid thru the MC and also suctions/vacuums the old fluid thru the nipple valves. so why waste time and money on MacGyver type reasoning and dollars on a hit or miss system when you can get a Grand slam at every 30k miles by paying a pro $100 and leave there having a firm pedal, instead of mushy pedal due to air escaping thru the bleeder threads and whatnot nonsense.


Perhaps because when I do this myself, I don't have issues with mushy brake pedals? And save myself $129 or whatever a local shop will charge.