vacuum bleeding??

[BuickMike231]

Yep follow the normal order of starting at the furthest wheel. Works great.

 

[1KWIKSIX]

Yep follow the normal order of starting at the furthest wheel. Works great.

Hey Mike,
Any special procedure with the buicks brake proportioning valve when doing the rear brake cylinders?
Thought I read somewhere that you need to clamp the rubber button in order to bleed the rear brake cylinders properly?
What have you found regarding this.

thanks
dave

 

[The Granny]

Hey Mike,
Any special procedure with the buicks brake proportioning valve when doing the rear brake cylinders?
Thought I read somewhere that you need to clamp the rubber button in order to bleed the rear brake cylinders properly?
What have you found regarding this.

thanks
dave

when I vacuum bled mine I didn't hold that button down. my brakes work good

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[BuickMike231]

I agree, I've seen people talk about that but using the Power Bleeder I've never touched the prop valve. The lines bleed great and the breaks are fine. I wouldn't mess with it.

 

[1KWIKSIX]

Thanks Gents.....so after fastening the plate onto the master cylinder & pouring in brake fluid into the tank and pressurizing to 15psi....hook up the tubing, then simply open the brake nipple and let the fluid run out into a catch container until there is no air present. Close up the nipple and on to the next one? I have never bench bled my master cylinder. Am I correct in assuming that with vacuum bleeding this takes care of any air in that area and bench bleeding the master cylinder is not required?

 

[1KWIKSIX]

Having a hard time sealing the 0115 (larger plate) to the master cylinder reservoir. Had a difficult time getting it to hold , but eventually got it to 10 lbs, when it hit 10 lbs I heard a hissing and knew I had a leak somewhere....brake fluid pouring out from under the car. Looks like the plate isn't sealing worth a shit! I had all the chains tight and even a couple of clamps installed which needed to be progressively tightened to be able to reach 10 lbs. Maybe a gasket could be installed between the plate and the master cylinder? Not sure if the plastic reservoir is deforming when clamped under load? Any suggestions would be appreciated.

 

[BuickMike231]

Sounds like you may be having the same issue I did. If you watch closely on the sides of the reservoir when you pressurize the bleeder, I bet one of the sides is bowing out a little. That happened to me. If I remember correctly I had a big C clamp right in the center of the plate, another on one end that never seemed to seal up nice, and a third clamp running from side to side (parallel to the front of the car) to keep the reservoir from moving. Sounds dumb but it worked immediately after getting that set up. You may have to play with the clamp locations based on your reservoirs actions. I chalked it up to 30 year old plastic, not really the bleeders fault. Once it's sealed it's a quick job.

 

[1KWIKSIX]

Thanks Mike! I believe that's exactly what's happening here. The plastic reservoirs walls are expanding under pressure and the seal is failing.
Also spoke with Eric (tech guy) at Motive Products and he has confirmed same. Suggested making sure that the rim of the revervoir is clean and spraying with brake cleanser. In addition , spray brake cleaner to the gaskets surface of the aluminum plate . This will ensure not only a clean surface, but the brake cleaner will make the gaskets surface a little tacky and will help grip. Next , install a pair of small wood pieces clamped to the sides of the master cylinder reservoir (this will aid in limiting deflection under pressure) and a single large C clamp attaching the Motive Aluminum plate to the reservoir. He suggested 5-7 psi would be sufficient to vacuum bleed the G body plastic reservoir successfully.

 

[BuickMike231]

Awesome. That sounds about right. I think I got mine to 10 psi or whatever they recommended in the instructions. Hope it works for you!