Bench Bleeding a Master Cyl With Power Bleeder.
12-31-2021, 04:23 PM
#1
Bench Bleeding a Master Cyl With Power Bleeder.
I do all my families (and some friends) auto maintenance which includes brakes. I was gifted a Motive Power Bleeder a couple years ago and love the great help it provides and wanted to share here.
There are tons of info on this bleeder but nothing about using it to bench bleed a new master cylinder. I experimented on my 2005 Silverado recently coming out very happy with the results.
Normally it requires chucking the master cylinder in a vice with outlet port adapters to run clear hoses back into the reservoir, and lots of time is spent stroking the piston viewing the air bubbles in the hoses. Rapping the cylinder with a screwdriver handle to move clinging bubbles out and repeating several times. Its a PITA.
I had the bleeder on the bench and it prompted me to run the hoses into the fluid bottle and connect the pump to the reservoir.
With just a few pumps it starts moving fluid and I was happy to see bubbles moving through the hoses. I stroked the piston by hand a few times slowly getting more. Nice! I had it purged in 5 minutes.
Just keep an eye on the reservoir level it moves fast enough to push air into the cylinder if you ignore it too long, even with only a few pumps.
I'll go further on when I install the master cylinder and fasten the lines I'll connect the bleeder, lay a rag under, and crack the fittings one at a time to hear it spit the air out. Just a couple pumps. Too much and you make a mess and the air may not purge.
After doing this I see very little air when bleeding at the wheels.
Tip for new power bleeder users to avoid spillage:
(1) Fill the reservoir to normal level and connect the cap adapter. The manual says pump to 10-15psi but to check for a good seal just pump to 5psi and eyeball the fluid level in the reservoir. If you have a leak it will rise and leak push fluid through the leak. If you have a leak crack open the tank cap and turkey baster some fluid out and try again.
(2) When you see all is good pump to 15psi and eyeball it again for a minute or two. If the lever is steady you are good.
(3) When you are finished "Do Not" remove the reservoir cap adapter first! Twist open the tank cap to let the air off. There will be bubbling and gurgling and the level in the reservoir will be the same as when you started.
There are tons of info on this bleeder but nothing about using it to bench bleed a new master cylinder. I experimented on my 2005 Silverado recently coming out very happy with the results.
Normally it requires chucking the master cylinder in a vice with outlet port adapters to run clear hoses back into the reservoir, and lots of time is spent stroking the piston viewing the air bubbles in the hoses. Rapping the cylinder with a screwdriver handle to move clinging bubbles out and repeating several times. Its a PITA.
I had the bleeder on the bench and it prompted me to run the hoses into the fluid bottle and connect the pump to the reservoir.
With just a few pumps it starts moving fluid and I was happy to see bubbles moving through the hoses. I stroked the piston by hand a few times slowly getting more. Nice! I had it purged in 5 minutes.
Just keep an eye on the reservoir level it moves fast enough to push air into the cylinder if you ignore it too long, even with only a few pumps.
I'll go further on when I install the master cylinder and fasten the lines I'll connect the bleeder, lay a rag under, and crack the fittings one at a time to hear it spit the air out. Just a couple pumps. Too much and you make a mess and the air may not purge.
After doing this I see very little air when bleeding at the wheels.
Tip for new power bleeder users to avoid spillage:
(1) Fill the reservoir to normal level and connect the cap adapter. The manual says pump to 10-15psi but to check for a good seal just pump to 5psi and eyeball the fluid level in the reservoir. If you have a leak it will rise and leak push fluid through the leak. If you have a leak crack open the tank cap and turkey baster some fluid out and try again.
(2) When you see all is good pump to 15psi and eyeball it again for a minute or two. If the lever is steady you are good.
(3) When you are finished "Do Not" remove the reservoir cap adapter first! Twist open the tank cap to let the air off. There will be bubbling and gurgling and the level in the reservoir will be the same as when you started.
01-01-2022, 12:51 AM
#2
From my experience there is no reason to bleed a master with a motive bleeder, the whole point in using air pressure to bleed is to push all the air out, without help.
the only issue ive ran into is, if you have fluid in the motive pressure bleeder and no caliper bleeders open or not actively bleeding calipers, the master will fill up and over flow eventually unless u release the pressure. Aka you need to be pretty fast to do calipers one at a time by yourself with pressure in the system or the master will fill up quickly.
my 2cents on a motive since you posted..
the only issue ive ran into is, if you have fluid in the motive pressure bleeder and no caliper bleeders open or not actively bleeding calipers, the master will fill up and over flow eventually unless u release the pressure. Aka you need to be pretty fast to do calipers one at a time by yourself with pressure in the system or the master will fill up quickly.
my 2cents on a motive since you posted..
01-01-2022, 01:59 PM
#3
I bench bleed a new master cylinder in a vice before mounting it. The Motive is great for that.
I pressurize the Motive bleeder all the time with the system closed. Its in the instructions to do so, and to observe the gauge for a minute to check for a leak. If the leak is at the cap the reservoir will over fill even if a bleeder is open.
I pressurize the Motive bleeder all the time with the system closed. Its in the instructions to do so, and to observe the gauge for a minute to check for a leak. If the leak is at the cap the reservoir will over fill even if a bleeder is open.
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