dburgjohn

I bought one because many here seemed to love it.

Just finished replacing all lines and MC and tried the Motive pressure bleed out. What am I missing? It hooked up fine (the board and c-clamp version I read about here) and held pressure but nothing came out. I hooked up my old vacuum pump to the bleeder screws and out came the air and fluid. The pressure Gage on the motive dropped as it came out but only with vacuum on the bleeder. I tried more pressure, but still nothing without vacuum.

I thought you just pumped it up and opened the bleeder. What did I miss?

GDaina

don't know...don't need much pressure, about 5 lbs is all you need

GDaina

I have the cheapest pressure bleeder that works...I just drilled a hole in an an old master cyl cap, put an air fitting in it, attach the air hose, turn the pressure to 5 lbs and I'm in business, just have to be careful not to run the cyl dry.

noonie

About the only thing that will prevent fluid from passing thru the MC is if the MC rod is not in the fully retracted position. Either out of adjustment, not seated correctly or too long a rod. Operate the MC, looking into it and make sure the piston cups retract fully past the little fill holes at the bottom.

Other than that, a porportioning valve will block fluid to either the front or rear system, but not both.

Lastly the flex hoses at all wheels can be collapsed, but that is not likely.

It does take a lot of fluid to fill any empty system.
You can flush with up to 80 psi, but bleed with the minimum pressure that pushes fluid.

dburgjohn

The booster, master cylinder, all metal lines, flex lines, bleeder screws and front calipers are all new. The vacuum pump pulled the fluid fine but the pressure from the motive seemed to do nothing. It did drop as I 'pulled' fluid but it 'pushed' nothing.

I don't remember the exact pressure readings on the motive but I tried it at 25%, 50% and 75% of what the dial showed.

The booster came with two rods, a short one in the booster and a longer one in a separate package. The longer one was way to long so I left the shorter one in place.

AzMotorhead

dumb question but your Motive bleeder has fluid in it?
I went to Lowes depot and picked up a 6ft length of vynil tubing and use that between the Bleeder and MC.
Can you see fluid moving from the Motive bleeder to the MC?
DId you bench bleed the MC?

540 RAT

It doesn't have to have fluid in it at all, you can just use it for pressure only. In that case, only the MC needs to have fluid in it. Just don't let 'er run dry.

rajsid

And it's recommended to stay under 15 lbs.

dburgjohn

no fluid in tank, only fluid in MC. I know it pumped up because I heard it leaking first time before I snugged down the C-clamp. Plus as I bleed it with vacuum I could see the pressure gage drop. It did not drop during my supper break. what gives?

MC was bench bleed was was done prior to install. The bleed is going as expected for a vacuum only bleed. The motive seems to be doing nothing. I just don't know why.

TXredc3

I'd try attacking this like you would an air leak in one of your vacuum hoses (ie - headlights). Start unhooking things to identify the culprit. Maybe start with the hard lines that connect to the master cylinder. If under pressure the fluid flows coming out of the master cylinder then you know the MC is good. Then re-hook up the lines to the MC and unhook after the proportioning valve. So on a so forth. It'll be a little messy but it should be effective. I'll bet you it's your proportioning valve. Good luck.

QuicheLorraine

Guess that's as good idea as any. It will be messy; just have plenty of water around to pour on the situation. I've done brakes & front end for a lot of years and the only things I can think of here have already been mentioned. And they both revolve around the Master Cylinder:

• Be positive to bench bleed properly
• make sure the brake pedal is returning to top

dburgjohn

but if there was a blockage no fluid would have come out at the wheels. I got air then fluid using the vacuum pump. If there was a blockage I could understand not fluid movement but there was, just pulled not pushed.

pws69

How are you connecting the Motive to the MC cover? If you are using a snap coupling, make sure the male and female are matching configurations. There are some combination's that will snap together, but the "shutoff" in the actual snap coupling does not release.

If it was the proportioning/differential valve, you should still get fluid out of one end of the vehicle.

dburgjohn

I did pull the valve when I removed the old lines. I unscrewed the valve by accident because when I put the line wrench on, it came off rather than the line fitting removing from the valve. I put it back, cleaned it up and blew it out with air hose.

could I have damaged it in some way?

how do you test?

tried to bleed more today, pedal drops to the floor with nothing. Some fluid comes out of some bleeder screws.

what did I do to drive myself crazy before I got bit by Corvette bug?

dburgjohn

looking at this and other forums I wonder if my use of the air hose could have blasted the piston in the valve and jammed it to one side?

Or the fact that when I tried to remove the line to the rear, the valve unscrewed into two parts. It did not seem damaged so I put it back together. The old rear line fitting was frozen to it and had to cut line and remove fitting after valve removed from car.

dburgjohn

Corvette central to the rescue, new one on the way

dburgjohn

new Porportioning Valve installed, fluid flows

MN-Brent

Old cars, what you gonna do!!!!!

Glad to hear you sorted it out. You now get to move on to the next project

okaythen

Manual says Denatured alcohol but will any rubbing alcohol do? And just swirl it around the bottle, run it through the tubes right.

Mooser

This thread is 9 years old (you should start a new one)
But to answer your question, yes it will work with rubbing alcohol or even methyl hydrate
M