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Vacuum Brake Bleeding


PeterH
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we did evacuate and  fill on hyd  systems  truck line  back in the 90s,  you do need hydraulic seals that take care of not leaking under vacuum, our system was total vac, ie absolute takes some  pump for that . it would not let fluid in if the vac was not achieved, then opens valve and in rushes a known amount in a flash , no bleeding or topping up.

past history now for me ,  but thats the only one ive experience of 

does the MM vacate the system to allow a fill or does it vacuum the bleed nipples ????

Pete

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I found a YouTube vid of an American using a similar device.

It consists of a hand operated pump that vacates a small reservoir. This is then attached by a transparent tube to the bleed nipple and sucks the fluid / air out until only fluid is visible in the tube. (MM part 040817932, latest catalogue says it New). Amazon also have them from several sources - looks like same tool - some with good reviews other poor, hence my query.

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Well ive never had any problems with foot power, some vac on the nipple assists the flow so long as it doesnt leak down  the nipple threads   .

In fact the earlier assy. line side system was pressured in the feed and vacuumed from the nipples , mainly to return the used fluid to a slave tank to rest.

I use a  quick down slow back often with a nipple nip between strokes, have a long hose and have the bleed bottle up high, not down on the floor, keeps the nipple threads charged , and all bubbles rise 

I have an electric pressure pump which tends to hold more than needed and risk leaks at the reservoir when you find the cap is a leaky fit

So its Simple basics , low cost , no gremlins  works , avoid must haves 

Pete

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I've got a garage full of 'gimmicks' for bleeding brakes - Eezibleeds that use tyre pressure, vacuum pumps that use both hand pump or compressor-driven vacuum, and I've practically binned them all in favour of pedal pressure and a short length of plastic tube.

I say practically because I'm experimenting with one of these:

pump.jpg.33a183a9db8cf31210de23f32a33689e.jpg

I saw one in operation recently draining brake fluid from cars that were being prepared for crushing and was impressed by the flow rate and pressure - a nice slow steady speed that would work very well if filling a system for the first time; as for bleeding, I'll test it over the next week or so and report back. It's not the sort of high-speed flow that would empty a master cylinder in seconds and is controllable by the switch on the unit, so it's very manageable by one person. I think it cost me £11.99.

 

 

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Have heard of people using the pump dispenser from a liquid soap bottle, just connect pickup tube to bleed nipple with clear tube. It was also suggested to put some grease around the bleed nipple to stop air being drawn down the threads and giving a false indication.

Never tried it but principal seems good.

Regards

Paul

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Hello Peter,

I have always used the plastic tube with a one way valve fitted at the end direct in to a jam jar - has always worked for me.

Gave up on the Ezibleed system after it disconnected and resprayed the engine bay on a classic 😒

One tip I will mention, is that when you have completed the bleeding process, use something (I use a piece of timber) to hold the brake pedal down for at least 12x hours. This really does get rid of those very fine air bubbles which when added together can make a difference to the pedal feel.

Additionally it also tests the integrity of the hydraulic system.

An assistant to do the pedal pushing is useful if you have one to hand; a Scout on "bob-a job-week" is always quite timely !! 

Good luck.

Richard.

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I have probably spent more money on brake bleading than any other tool and the one I always end up back to is the cheap-as-chips Visibleed (usually bleeding on my tod).  They don't last for ever - but also only cost £3.50!

I've got one of the eBay versions of the MM tool and never seem to be able to get a tight-enough fit to the bleed nipple, so you just get 'foam' as it pulls more air around the seal than flud through the nipple (even with 68viteesse's greasy nipples).

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I've tried pressure and I've tried vacuum, and misquoting Sophie Tucker, neither is better.       I use a long broom handle that allows me to reach the brake pedal from either side of the car, through the open door.     A short length of plastic tube fixed to the end has a notch in it that engages on the pedal.   Then, I can watch the tube on the bleed nipple and see when the bubbles stop.

Simples!

John

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