bleeding brakes with a vacuum pump

Post by **Pascal** » Mon Nov 26, 2007 2:46 pm

Hi,

Has anybody tried to bleed brakes with a Mityvac vacuum pump? Does it work well?

The idea is that rather than pushing fluid from the master cylinder by depressing the pedal, you suck old fluid (and air bubbles) from the bleeding nozzle at the wheel, hence easier operation.

Regards

Post by **MoggyTech** » Mon Nov 26, 2007 5:03 pm

Problem is with the ported piston design of the Moggy Master Cylinder, you can get problems with vacuum bleeding. The non return valve Easy Bleed system seems to be the best.

Post by **Pascal** » Mon Nov 26, 2007 5:08 pm

What kind of problems? I'm keen to know before I start!

Post by **MoggyTech** » Mon Nov 26, 2007 5:28 pm

You will need to wedge the brake pedal to the floor before bleeding.

Post by **paulhumphries** » Mon Nov 26, 2007 6:30 pm

I couldn't get a decent pedal using my Mityvac.
I think problem was the rear circuit as the bleed nipples are such a loose fit.
In the end the only way, after numerous attempts, was the traditional two person method.
I've a Gunsons pressure bleeder but aren't happy with that either as I lent it to a mate and since it sprays brake fluid out so haven't tried on my Minor as the last thing I wanted was brake fluid sprayed around interia !

Paul Humphries

Post by **IaininTenbury** » Tue Nov 27, 2007 12:31 am

I use a Gunsons pressure bleeder at work, and consider it great. You have to modify an old Mcyl cap by drilling a hole in the top for the tube to fit in, and then blank off the breather on the side of the nut (I just screwed a self tapper in) and away you go. If it sprays fluid out, find the leak and sort it. (You could test it on an old cyl first rather then in a nice car!). Then its easy. Just go round the bleed nipples and open them like a tap till nice fluid comes out and, er, its done... Takes about 5 mins for a whole car from dry.

Post by **Kevin** » Tue Nov 27, 2007 9:03 am

Just a question Iain I assume that if you have one of the reservoir kits fitted with a disc brake conversion that the Gunsons kit would go straight onto the reservoir and still work in the same manner.

Post by **dunketh** » Tue Nov 27, 2007 9:46 am

What's wrong with the normal way of bleeding brakes?

By the time you've set up your vac and gotton started I could be already half way around the car if not finished.

I guess theres a place for all these weird methods if your system just refuses to bleed nicely but I've never had any problems.

Post by **steve4063** » Tue Nov 27, 2007 10:07 am

i use a gunson's pressure bleed too and thats mainly because its easier if you're on your own.

if my missus is about i'll use the normal way

as Ian said all you have to do is get an old filler cap and butcher it a bit but shutting off the breather hole and drilling a hole in the top for the pipe

it took some fiddling when i first done it and the fibre washers kept breaking but now its done its very handy bit of kit.

Post by **IaininTenbury** » Tue Nov 27, 2007 10:23 am

Kevin wrote:Just a question Iain I assume that if you have one of the reservoir kits fitted with a disc brake conversion that the Gunsons kit would go straight onto the reservoir and still work in the same manner.

The standard kit comes with a few caps to fit most common master cylinders. Its simply a matter of screwing the pipe end into the appropriate cap and then using it. I would guess that one of the caps in the kit would fit the remote reservoir kits as it'll be a standard Lockheed/Girling item, though I've never had to bleed a car with one of those fitted.

Obviously the kit dosnt have a moggy type cap which is why you have to modify an old one to suit. Really is dead easy when its all set up and invaluable when working on your own. I used to use a piece of wood to hold the pedal down, run round, do the nipple up, come back, release pedal, undo the nipple, press the pedal, insert wood etc etc...

Post by **dunketh** » Tue Nov 27, 2007 11:40 am

Funnily enough the last time I did mine I got my boss out there to operate the pedal!
"Err... are you busy at the moment..."

What else are lunch hours for?

Post by **Kevin** » Tue Nov 27, 2007 11:44 am

What's wrong with the normal way of bleeding brakes

i use a gunson's pressure bleed too and thats mainly because its easier if you're on your own

Takes about 5 mins for a whole car from dry.

So its a thumbs up if your are on your own then and not an expensive piece of kit either.

Post by **Orkney** » Tue Nov 27, 2007 11:48 am

how much are they ?

Post by **Kevin** » Tue Nov 27, 2007 5:34 pm

I think the recommended price is around £18 - £20 not exactly sure but you do find them on ebay for a bit less for example.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :IT&ih=019

Post by **Orkney** » Tue Nov 27, 2007 6:38 pm

Woew is that it ! looks like a lot of money for a squash bottle & bits of pipe through the lid sealed with silicone.... cant be that simple sureley?
That seller has some handy stuff - the brake repair kit e.g. screw extractors, wiper inserts a steal.
Damn you Kevin its on the favourites now and if the 3 spirits visit on xmas eve might have to buy something !!!

Post by **IaininTenbury** » Tue Nov 27, 2007 11:05 pm

Other advantage is that you're not operating the master cylinder beyond its normal range of travel, that is flooring the pedal. The problem can be, if a wear ridge has developed on the cylinder, bleeding the conventional way can harm the seal as it gets pushed over the ridge. I'd guess the vacuum pump kit has the same advantage, though never used one of those.

Mine cost £3 from a car boot sale, but I lost it in a house move so had no hesitation in buying a new one - about £15 three years back. Of course the first one then turned up so now one is permanently fitted with a Minor cap and the other gets changed for whatever. Useful to build up a collection of old master cylinder caps too - can be a better fit than the ones supplied in the kit and always useful to have a choice. Just modified a 1930's Hudson cap to fit for the last job I did - oddly that one wasnt supplied in the kit...