Pressure bleed...how much pressure?

[Seeker > 620 KC]

I bought one of those Motive pressure bleeders because my wife and I don't communicate on mechanics well enough to master manual brake bleeding together. I was hoping to bleed the system by myself with the Motive pressure bleeder.  It says to consult the vehicle service manual for the correct pressure to bleed the brakes. I couldn't find a thing in the manual, as I don't think they had pressure bleeders in 1979 -80.

 

Has anyone used a pressure bleeder that pressurizes the master cylinder and pushes fluid down to the bleeders? How much pressure did you apply successfully?

[thisismatt]

I don't think it really matters as long as you're not blowing apart the master cylinder reservoir.  What cap are you using with the Motive? 

[mklotz70]

I think I ran about 3 psi on the home made one I use.  The cap is a push on kind .....much more than that and it pops off.  If you have a screw on type....you could go higher, but I don't think you need to go much higher.

[DanielC]

I have found a unique problem with bleeding the brakes on my 521 trucks.  The wheel cylinders do not have a second port for air to come out of, when fluid is going into the cylinder, when bleeding the brakes.  To get air bubbles out of the wheel cylinders, the cylinders have to be allowed to retract, so there is movement of fluid, and air out of the wheel cylinder, to the bleeder fitting.

 

When manual bleeding, with two people, you simply hold the brake pedal down, and open the bleeder fitting.  Continue to hold the brake pedal down, until the flow of fluid out of the bleeder fitting stops.  Then close the bleeder fitting.  Then you can let the brake pedal come up, and repressurize the brake system.

 

My thought is that with a pressure bleeder, the pressure on the slave cylinder never goes to zero, and the pressure will hold air in the slave cylinders, and not allow that air to get to the bleeder fitting

[mklotz70]

Oooooo......great point Daniel!!!  Since the bleeder is on the same "Y" as the line, it just flows from the line to the bleeder.......doesn't even know the slaves are there.

[banzai510(hainz)]

dont need a pressure bleeder just use a plastic bottle with some clear tubing.

just use the wife to refill the master so it dont go dry. or better yet have her pump the master. and you watch the hose for bubbles. when none tighten it up

[Seeker > 620 KC]

ThisisMatt

I have the Motive 0126 kit description is :

For use on small round reservoirs where the 1101 is too large. Typically for but not limited to use on Datsuns such as the 240Z and 510s. Mid 1980's Corvettes with two round M/C reservoirs. Also fits some small clutch reservoirs. Comes with tank, pump, and 1126 adapter.

It has a dinky chain device to wrap around the master so the lid can't pop off.

 

If the system is problematic maybe I can use it to get the majority of air out of the lines and finsih when a friend can help me. My wife is who she is and I dont' fault her for it. She'll space out putting the cap back on the reservoir, or will lift her foot off the pedal in mid stroke. She just doesn't give credance to the importance of following direction on mechanical stuff.  

[MikeRL411]

Instead of using a pressure flush, why not use one of the "vacuum" draw units that slip over the nipple of the wheel cylinder?

[Seeker > 620 KC]

MikeRL411, The power bleeder was an impulse purchase solution vs. bleeding brakes with wife. At the time I thought big tank with large volume of fluid was easier than vacuum pulling fluid and refilling the res more often. Now I see the power bleeder has its downsides with operation as well as more cost. In hindsite I think the vac solution would be more effective and less problematic.

 

As for Daniel C and MKlotz's discussion I think I may have lucked out. Current application is for my 80' 200 SX which has disks all around. The line and bleeders are not on the same Y. But I could have that problem on my 79 620 rear drums. Will have to look and see.

[bananahamuck]

I use the one-way valve hose type brake bleeder just drop one end in fluid and slowly pump and tighten valve when your almost done for more pressure.  http://www.rakuten.com/prod/alltrade-648400-one-man-brake-bleeder-hose/229481765.html?listingId=319331848&scid=pla_google_toolsmithdirect&adid=18172&gclid=CN-93pKRtL0CFVBffgodk1MAFA

 

You already have pressure thing so you should just try/play with that first as i bet when you get the knack for using it,, it probably would be a easy peezy.

[TENDRIL]

making my own i hope it works....

 

[Seeker > 620 KC]

Wrap some zip ties around the cap and reservoir. If you use too much pressure I've read it will pop the cap off. Mine came with a little chain and some J-bolts to tighten it down. I was going to try it out last Friday night. But when i came home at lunch for a quick sandwich...I found my house had been burglarized. Broke a kitchen window and tossed/trashed the place just like in the movies.