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MG MGA - Bleeding the Master Cylinder

I am back helping my friend getting his MKII back on the road. We have rebuilt the master cylinder and replaced the clutch supply line. We are getting nowhere in getting either the clutch or brake lines bled. I can feel air being pushed out the bleeder on the clutch and a vacuum being pulled when the clutch pedal is released. The fluid level in the M/C is not changing. I remember it took a long time to get mine bled but not as long as we have already spent on this one. We removed the M/C cover and can see the end of the pistons through the fluid supply hole.

Any ideas will be appreciated!
Thanks,
Don Carlberg
D. R. Carlberg

Don

I use the Eezibleed system. Takes about half an hour or less to bleed both brakes and clutch. It's also a one person job. No brake and clutch pedal pumping.

Here is the system if you are unfamiliar with it: http://www.aep.bigstep.com/eezibleed1.htm

Steve
Steve Gyles

Steve, thanks for the input. I looked at that on Barney's site and have seen it mentioned on this board several times. Didn't think I needed it since the car owner provides the pedal power to exercise the M/C. We just don't seem to be able to get any fluid into the system. I guess we will keep trying.
Don
D. R. Carlberg

Get the Eezibleed. With a helper on the pedal, and Eezibleed, bleeding brakes and clutch on an A takes less than 30 minutes and success is guaranteed. I have a Vac system too, which is totally useless compared to the Eezibleed.
dominic clancy

I too had a problem bleeding the clutch after fitting a newly resleeved m/c - the problem is that there is no valve on the clutch side so pumping the pedal just moves the column of fluid (and air) up and down the line without getting the air out. In the end it took patience and about two days. The air will eventually work its way to the top.
I have not tried the "easibleed" system, but can't think why it would work on the clutch, but you have several testimonials here.
Someone did suggest the following technique when I asked for advice - connect the bleed screew of the clutch slave to the front right hand brake bleed screw(nearest)with a pipe and open them both up. Pump the clutch pedal slowly, pushing fluid from the clutch line into the brake line and the m/c, where the valve in the brake side will prevent the fluid running back up the clutch line.
I did not try this. it is also suggested as a method to be used "on the road" if you have clutch problems. Just carry the length of tubing in your tool kit.

I have not experienced problems bleeding the brakes, so perhaps you have reassembled the m/c piston incorrectly. I always start with the left rear wheel as this is the furthest from the m/c.
Peter.
P. Tilbury

There is a lot of information on this subject in the archives. That said it sounds like the seals are not returning properly, stiff seals (normal for new) or weak springs (stretch em out it helps).
Pumping slowly is better that franticly. Sometimes I have used pressure (10-15 psi through a rubber tip from a plug-in compression tester) at the M/C resevoir fill hole to get the process started. A vacuum device from the wheels and slave helps also.
Make sure parts were assembled in proper order use a exploded diagram to be sure. It is also very easy to install the front seal that goes around the piston improperly causing it to bind. Is the check valve in the brake side in proper order?
R J Brown

We are contemplating pulling the M/C out for disassembly to check to make sure that we did not have a "senior moment" and got the two reversed. It looks like it will have to wait until after the Masters Golf Tournament before we get back to it again.

Thanks to all.

Don
D. R. Carlberg

This is another reason to use silicon fluid. If you are you can take it apart right there on the car and fix it. Without the danger of damaging paint.
R J Brown

Before you tear it apart try the following, an extra leg is needed. Open the bleed nipple, push the pedal down and hold it down, close the bleed nipple, release the pedal. This stops the air from just going back and forth as closing the bleeder causes a vacuum to form in the line when the pedal is released, helping to draw fluid into the lines.
John H

Sorry, John H, that is the conventional way to bleed hydraulics but it does not work on the MGA clutch. I know, as I tried it over and over again with my wife on the pedal. Even tried pumping fluid up from the slave to the master using a big syringe/pump. No joy.
Peter.
P. Tilbury

The method JohnH describes has always worked for me.

An additional thought is to remove the slave from it's mount and hold it so that the bleed screw is at the top alowing the trapped air to escape more easily while bleeding. Clamp it (I use some bailing wire through the pushrod)to keep the piston from flying out and CLOSE the bleeder BEFORE the pedal is released.

As RJ mentioned pumping the pedal rapidly does nothing but atomize the air in the line causing you to wait for it to settle. Big air bubbles are easier to remove than small ones.

If it still doesn't work then there are other problems.

Flex line to the slave OK?
JohnB

If you turn the clutch cylinder around with the bleed nipple pointing up you won't get the air out, because the internal fluid passage is not in that location. The best position for the slave cylinder when bleeding is standing on edge, just as it is mounted in the car. See here: http://mgaguru.com/mgtech/hydraulics/ht106.htm




Barney Gaylord

Bleed the masters on your workbench BEFORE installation. Much nicer to do it twice if necessary.
Martin

Every time I go to blead brakes (or clutches) there never seams to be anyone around to help. I use a clear plastic hose with the end in a baby food jar half full of brake fluid. I set the jar on something to keep it close to the bleader. Pump it slow and keep the master full. The air will come out and the fluid will get sucked in. I takes a little time but does work.
Jim.
Jim J

I have to say I fail to see what the problem is. I mentioned in my first post that Eezibleed does exactly what it says. It is so easy and worth every penny of investment.

I rebuilt my master cylinder last summer. I did no priming of the MC etc, did no fancy angling of the clutch slave cylinder. I just filled the MC up, connected Eezibleed, bled the system and was driving the car within the hour.

Steve
Steve Gyles

I agree with Steve -the Eezibleed system works great - I did have one problem after renewing the rubbers in the master cylinder though and that was that the new rubbers kept sticking in the cylinders - so although most of the air had gone from the system it took a while to get pressure up on the pedal- I found that working the piston back and forth a few times before reassembly made it bed in more quickly. I did have to rebleed the system after a few miles run as some trapped air bubbles dislodged themselves.cheers Cam
Cam Cunningham

Looks like we will invest in the Eezebleed. I gues with two MGAs in this little town we will probably put it to good use. Thanks for all the suggestions. Really appreciate the help! I'll let you know how this all comes out in a couple of weeks.

Don Carlberg
D. R. Carlberg

Has anyone ever ordered from the page Steve linked? ( http://www.aep.bigstep.com/eezibleed1.htm) I've never heard of these guys, but the price is about $12 less than Moss Motors.

Thanks
Darian Henderson

I made my own "Eezibleed". I found an OLD Marvel Mystery Oil can cap was an exact fit for the MGA dual master cylinder. (It is VERY hard to find a random cap that will fit.)

I drilled a hole in the cap and installed the valve and sealed it. Set the compressor regulator to 15PSI and hooked it up. It did the job on brakes and clutch in 15 minutes. Great idea--price, just stuff around the shop.

I tried every cap in the shop before I found an OLD one the did fit.
Jim Ferguson

I don't have an air compressor. So for $22.00 built one of these: http://www.bmw-m.net/TechProc/bleeder.htm

I use an old MGA cap with it. Highly Effective.
Steven Loe

Darian

I was not necessarily recommending that supplier in my post. It was just the first USA-based supplier (with picture) that came up in my Google search.

What Jim has done is also how Eezibleed can be used. It is not absolutely necessary to fill the bottle with fluid. However, filling the bottle allows you to bleed the whole system without having to disconnect. If you leave the bottle empty or have a direct air line to the MC as Jim describes, you have to disconnect after bleeding each brake to top up the MC.

I found that filling the Eezibleed bottle is ok, but when you have finished bleeding the whole system you find that the MC is filled up to the absolute brim and you need to drain a small amount of fluid - not that it is a problem.

Steve
Steve Gyles

This thread was discussed between 23/03/2007 and 27/03/2007

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