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Mityvac pump

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MattP

MattP

Jedi Knight
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Just bought a Mityvac vacuum pump to bleed my clutch, any experiences, warnings, ect I should know?

I had it with me at work last night to study it, and threatened that anyone that went to sleep would wake up with an artificially produced hickey. /ubbthreads/images/graemlins/devilgrin.gif But I need constructive things to do with it. /ubbthreads/images/graemlins/jester.gif
 
You may find you need to wrap some teflon tape on the threads of the bleeder to avoid sucking air into the system. If you are getting air this way you will see many small bubbles as you bleed that will not go away.

Just wrap the threads, don't get it down around the tip -- I cut the tape in half lengthwise so it isn't so wide.
 
I don't think that you'll need the teflon tape for the hickey's. But the bleeding can be treated with some bandages - just be careful where you administer the hickeys and there shouldn't be too many bubbles while bleeding them /ubbthreads/images/graemlins/smile.gif

Just kidding !
 
Sadly, I was not able to bleed my clutch properly with my Mityvac vacuum pump. It works OK on the brakes but the clutch circuit was most difficult. I had to pressure bleed it from the slave cyl back to the master cyl by using a large, fast flow -- about one quart of brake fluid. I used the Mityvac components and my compressor set at 15psi. I collected the fluit out the top of the master cyl with an old modified cap.
 
Never pump fluid directly through the pump. Always use the catch cup for bleeding, extracting or filling. Putting automotive fluids into the pump chamber will perminantly contaminate the pump and likley damage the seals.
I had to explain this to my previous boss after he ruined our shops pump with brake fluid. (left it sit for a time with fluid in it and it was non functional the next time I needed it).
They ar also extremely handy for checking vacuume operated items, like the advance mechanism, and EGR valves
 
I think I'd have to echo Craig's comments on bleeding the clutch with the Mityvac. I used it, but it took more than once. I ended up having to close the bleeder, work the clutch a few times, and bleed it again. It took a few times to finally purge all the air out. And since the clutch master cylinder doesn't hold much, you can run dry very quickly using the vacuum pump. Hint: This is the voice of experience!

On the other hand, it worked great for the brakes, and I didn't have to worry about activating the PDWA switch as you would having a helper pushing the brake pedal. For that matter, you don't need a helper, although it would be nice to have someone topping off the reservoir as you are bleeding.

Just my $0.02,

-Dave
 
I had an opportunity to use the Mityvac pump when I replaced the resleeve brake master cylinder on the AH 3000. Unfortunately, it did not have enough vacuum pressure for initial priming, and continued to wimp-out when bleeding. Needless to say I could not perform a successful bleed with Mityvac and had default to the old fasion approach to bleed the system properly. After the system was fully bled, I attempted to use the pump once more. So properly set-up only a dribble of fluid flowed through the line; not the steady stream I was expecting.

So I'm interested, aside from following the manufacturer's instructions is there a secret to this operating this little device or should it be thrown in the draw along with other novelties? GONZO
 
I remember in the Mityvac instructions that it said you needed to "bench bleed" M/Cs before they went on the car which may be the reason you had difficulty. And... the vacuum provided is from such a small piston area that constant pumping(squeezing) is necessary to move lots of fluid. This is why it's almost best to use a pressure bleeder when purging a complete system.
 
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