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MG MGB Technical - opinion on the mityvac vacume pump

I am trying to bleed the clutch on my 75 1500 and it is a real bear! I have tried everything to get this gob of air out but no dice. I have tried to reverse bleed it with a bottle and clear tube. It got a lot of air out but there is still a patch that I can't get through. So I thought I better get that mityvac vacum bleeder to do it. Before I drop $50.00 for this little item I thought I would ask for some of your experiences with it. Will it do the trick?
Derek Lofgreen

I like my mytevac but it is of mixed usefulness on bleeding brakes. It is best when used with the adaptors to pressurize the master cylinder and force fluid through.

Insofar as the clutch is concerned, I have found time to be my friend. I fill it, bleed as best I can, then leave it for the night. Next day I top up, re-bleed and am good to go.

Mike!
mike!

I have one that I bought at Autozone. (Local parts house)

I am not overly impressed.

The two person "pump and bleed" works best in my opinion.

I do have a friend that swears by the "Eazi-Bleed" system. It works via air pressure from your tire.

FWIW

rick
rick ingram

I have have pretty good luck with it. If I was to buy it again I would have picked the all metal construction.

Using the small container for filling is pain in the *** however. They do sell a kit for that.

Shareef
Shareef Hassan

75 1500 sounds like a midget! I used to have
one, and I found the eezibleed works much better
than the mityvac. (Same applies to the B.)

However, use a very low tire pressure (10 lbs or less)
to avoid leaks. Put lots of paper towels around
the cylinder you're working on in case of an
accident.

Check Midget Technical Archives for lots more
info about the troublesome 1500 clutch.
Things like a missing pivot pin and bad
plastic hose can cause similar symptoms to air
in the hydraulics.
Ronald

Derek,
I paid $28.00 for mine. Once you get used the vac. pump it works well. I used it to find a cloged gas vapor return line.

Ron
R Garcia

I've got a well used one. Quite happy with it. I like the pump/vacum to blow or suck out pipes -- and the vacume gauge is a handy device to check the general condition of how the engine is running.

Just hook the gauge somewhere on the intake manifold.

I'm a bit unsettled on using air from the tyres. I hear that one works well, but still seems rube goldbrick to me.

There are many "great sucking sounds" all across the states -- good luck with which ever way you go.
glg

I use mine whenever I've done work to either cars' hydraulic systems. The only thing to remember is that the bleeder fittings are a loose fit and you can suck air through them using the mityvac. A little grease or old fashiioned modeling clay around the fitting seals it. When bleeding the clutch cylinder--make sure it's piston is fully compressed in it's bore.
R. L Carleen

Derek,
You don't need to get a MityVac for that, though they are really useful for number of tasks.

Try this.

Reverse Bleed Technique for Clutch
Empty system of fluid completely. Get inexpensive pump style oil can or “oiler” with tip that will permit a small plastic hose to slide on (or cut off any big honking end fitting). Fill with brake/clutch fluid. Put plastic tube on and the other end on the slave cylinder nipple. Leave top off clutch master cylinder and have someone watch while you do this so you don’t overfill and have it run over. Open nipple with wrench and pump fluid back up through system. When master reservoir 1/2 full, hold pump handle down and close nipple. Then top off reservoir.

5 minutes and done. Something about pumping upwards that precludes air staying in system

Got this from 30 year mechanic who started on LBC's, worked on Mini racing team and was working on BMW's, Mercedes and Rover when he quit turning a wrench.

I am in Denver. Email me off the board if you ever want a hand. Two is nice sometimes.

John
J.T. Bamford

Just get the metal version rather than the cheapo plastic version. It works much better, seals better.
Bob Muenchausen

Derek,

I own a Mityvac, but I've never opened the package. My two cents worth here is that I bought mine off the shelf at Auto Zone for much less than $50. I think it was about $30, and I didn't have to wait for it to arrive in the mail.

I will add this: Make sure all of the linkage points are in good shape. That is, the hole in the pedal, the push rod on the master cylinder, the push rod on the slave cylinder, the hole in the clutch fork, and the clevis pins which connect these. If you have enough slop in these joints, then you won't be getting a full stroke out of your clutch. This may add to the difficulty bleeding the system.
Matt Kulka

I can't comment on the Mityvac but I use a home built vacuum pump and it works great for me on all my cars. I've done my Midget brakes, clutch, and the brakes on all three of our daily drivers. The only problem is with the bleed screws leaking air around the threads when loosened. A little teflon tape seals this. It will draw fluid from a dry master cylinder completly through the system and bring the air along for the ride. Makes hydraulics a one man job.
Bill Young

Not sure if your slave is the same as the MGB or not but I just went thru the same problem with getting the air out of the slave on a 77 B. Come to find out the feed hose was attached on the side where the bleed valve belongs. I went thru a quart of fluid before giving up. After switching the hose and bleed valve and installing a new cup in slave it only took a couple of pumps of the peddle to bleed the air out.
Kevin Pearce

Hook hose to bleed niple on slave. Other end in old BF bottle empty. Open bleeder and slowly pump fluid thru master to bottle When you get half or so full bleed bottle your done. I work by myself and rarely have any problem with this method. If you get some really stuborn air you can put end of hose in master resevoir and bleed in a circle. Never has failed to work. Bob
Bob Thompson

Actually, this is why my mity-vac is still in the package. I use the same method as Bob, and am able to bleed the brakes alone. Except that I use a glass jar so I can see how much fluid I've pumped out, and if there are air bubbles in the hose. (I know, shame on me - I should be using plastic for safety.) I do try to let the pedal up slowly, so as not to suck back the fluid (and air) from the bleeder hose. But that may be overkill. The weight of the fluid in the lines tends to keep the master cylinder from drawing it backwards.
Matt Kulka

Mighty vacs are great when you have no one around to help you bleed the brakes. I have been using one for many many years and I never had a problem.
Mike MaGee

I love my Mity Vac and use it for all brake and clutch bleeding. It make me much more eager to tackle brake work, including changing brake and clutch fluid.

I also use it to pump oil through the dipstick hole in the transmission, usually a messy, tedious chore. I use my electric tire pump with the Mity Vac reservoir to do the job quickly.

As mentioned above, theyb are now available in stores for $30.
Steve Lipofsky

Did you try "bench bleeding" the clutch master cylinder before installing it? Doing this goes a long way in making it easier to bleed the clutch
system when using the "classic" pedal pump
method as it ensures thet the clutch master is
fully pre-loaded with fluid before it's installed.

Having said all that...

I love my MityVac - but - I've found that although it
works great for the brake system...I've had poor
or mixed results while using it on my clutch
system. After sucking through several quarts
(not pints) of hydraulic fluid, the clutch pedal is always left spongy-feeling and I cannot fully
release the clutch.

Although it is much better than the old dry pedal
pumping method, I've never been able to clear the
clutch system entirely free of bubbles while using
my MityVac - even though I've sealed the bleed screw threads with teflon tape, etc. Maybe it's the way the factory bent the hard lines on the clutch
system on my particular car (?).

Pressure bleeding the clutch system (not vacuum
bleeding) through the master cylinder seems to
work better in my case for this. Go figuire.

Other folks will extoll other bleed methods, and other folks have had much better luck with their own MityVacs - and they are all valid - but I've found
that what I've just explained here seems to work
best in my own, odd, corner of the universe.
Daniel Wong

This thread was discussed between 25/08/2004 and 03/09/2004

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