Bleeding brakes with vacuum bleeder
Burning Brakes
Joined: Feb 2018
Posts: 906
Likes: 196
From: Northeast, PA
This is true, but for mine it would only hold pressure if I held the cap on the reservoir. If I wasn't holding it, it would start leaking air immediately and by the time I crack a bleeder there's not enough pressure to push the fluid through the system. Hence why I turned the cap on "harder" and ruined the reservoir. I don't think I ever got the motive cap to click on the OEM reservoir, not the metal motive cap or the plastic motive cap.
Burning Brakes
Joined: Feb 2018
Posts: 906
Likes: 196
From: Northeast, PA
The next time I'm going to bleed the system with my Motive system, yes I have tried both metal and their plastic caps, neither really works well. Im going to try to modify a stock cap by adding a coupler to it and see if it will work.
But I just might be stuck in just using a thinner rubber gasket on the Motive bleeder like I finally did but still could not tighten the cap all the way.
Already got stuck in replacing the reservoir once due to the damage the metal cap.
If i had the ability and equipment I would just re-machine the metal cap and remove their reservoir destroying notches.
But I just might be stuck in just using a thinner rubber gasket on the Motive bleeder like I finally did but still could not tighten the cap all the way.
Already got stuck in replacing the reservoir once due to the damage the metal cap.
If i had the ability and equipment I would just re-machine the metal cap and remove their reservoir destroying notches.
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,821
From: Charlotte, NC (formerly Endicott, NY)
Not sure it's the same. Air bubbles are, always, on top of the liquid. Sucking from the bottom will always suck the liquid from the bottom. Pushing from the top, has a chance to push some of the air bubbles out. Air bubbles move slowly through a semi thick liquid, and can be forced through small tubes with pressure behind them.
I use a Motive and have a Vacula that operates off a compressor to generate a vacuum. I can get a greater pressure differential with the Vacula than I can with the Motive which I typically pump up to 15 psi. However, the Vacula can empty the brake line and reservoir very quickly and its use requires a person watching the fluid level in the master. Even with a vacuum hand pump, a person could gain as much pressure differential as they could with the Motive. The biggest issue with air in the lines is getting it into the ABS module as that can be hard to get out unless you have a tool that can activate the ABS valves and solenoids while bleeding. Air introduced at the bleeder screw in the caliper isn't going to travel up the pipe. It will settle at the top of the caliper if the bleeder screw is tightened while a vacuum is being pulled and captures air in the caliper that entered around the bleeder screw but hadn't been sucked out yet. When using a Vacuum Bleeder to bleed brakes, release the Vacuum and then wait a short while for the brake fluid to gravity bleed any remaining air out of the caliper before tightening the screw.
Bill
Melting Slicks
Joined: Feb 2018
Posts: 2,184
Likes: 1,050
From: North Texas
A lot of techs just put some grease around the bleeder screws to prevent any air getting into the vacuum line from around the bleeder screw threads.
And just clean it off afterwards.
I prefer the Motive system but have not solved the cap issue and wont use it until I do.
Motive should step up and make a cap for our reservoirs.
And just clean it off afterwards.
I prefer the Motive system but have not solved the cap issue and wont use it until I do.
Motive should step up and make a cap for our reservoirs.
Melting Slicks
Joined: Feb 2018
Posts: 2,184
Likes: 1,050
From: North Texas
Was thinking of adding a tire valve stem to my Motive bottle near the top at about the 75% height.
Adjust the pressure to the bottle from my compressors regulator to around 10 - 15 lbs.
Leave everything connected and start bleeding the brakes.
This way you don't have to tighten the Motive cap so tight and any air leakage will be replaced by the compressor as you bleed the system. Also no more hand pumping.
Adjust the pressure to the bottle from my compressors regulator to around 10 - 15 lbs.
Leave everything connected and start bleeding the brakes.
This way you don't have to tighten the Motive cap so tight and any air leakage will be replaced by the compressor as you bleed the system. Also no more hand pumping.
Drifting
Joined: Jun 2013
Posts: 1,294
Likes: 367
From: Iowa
A lot of techs just put some grease around the bleeder screws to prevent any air getting into the vacuum line from around the bleeder screw threads.
And just clean it off afterwards.
I prefer the Motive system but have not solved the cap issue and wont use it until I do.
Motive should step up and make a cap for our reservoirs.
And just clean it off afterwards.
I prefer the Motive system but have not solved the cap issue and wont use it until I do.
Motive should step up and make a cap for our reservoirs.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
I contacted Motive since I could not get a seal. Essentially their excuse is there's manufacturing variances in the thickness of the neoprene or rubber they use and since the smallest GM gasket won't work they suggested sanding it down to make it thinner and see if that works. I tried and couldn't get much material off so I gave up for now. You could try and see if that helps.
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Burning Brakes
Joined: Oct 2022
Posts: 1,090
Likes: 24
From: PA
I've been bleeding car and bike brakes for 50 years but my '19 GS is my first car with 2 bleed nipples per caliper. I use a vacuum tecnique with the compressor powering the bernuolli jet to suck the fluid through. My concern is on 2 of the calipers (left rear and right front) only one nipple would bleed. The other refused to allow fluid to pass. Has anyone seen this issue before and have a guess as to what the problem is? The other 2 calipers bled as per normal with both sides flowing.
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
I've been bleeding car and bike brakes for 50 years but my '19 GS is my first car with 2 bleed nipples per caliper. I use a vacuum tecnique with the compressor powering the bernuolli jet to suck the fluid through. My concern is on 2 of the calipers (left rear and right front) only one nipple would bleed. The other refused to allow fluid to pass. Has anyone seen this issue before and have a guess as to what the problem is? The other 2 calipers bled as per normal with both sides flowing.
Burning Brakes
Joined: Oct 2022
Posts: 1,090
Likes: 24
From: PA
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI