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MG MGA - Changing the brake fluid

Hi Chaps, My next task (when it warms up a bit) is to change the brake fluid on both the A and the BGTV8. The A was completely rebuilt in 2009, and the V8 (which I have used more) about 3 years ago, so I figure its about time for fresh Dot 4 fluid (I had researched switching to Dot 5 - I had this in my previous A - but decided against it since to do so I would have to renew all the seals). So my question is - what is the correct procedure for this? Since I want to refresh all the fluid, do I first have to siphon off the stuff that is in the master cylinder reservoir? Also, when I start flushing it all through, how much fluid is in the whole system to start with? Or do I pump it through at each wheel until I see a colour change (if indeed the old fluid has changed colour significantly)? And how much Dot 4 should I buy for the two cars? Your knowledge and expertise would be most welcome. Thanks, AB
A Bennett

Do what the garages do - pump it through until it's colourless - start at the rear. Buy one ltre of fluid and repeat every two years.
Roger Walker

AB, everyone has their preferred methods; I prefer a pressure bleeder. See attached link to the Guru site for info & details:
Nick Kopernik

I think you will need more than 1 litre for two cars. It's not expensive about 15 for a five litre container and then you can make sure it runs clear without worry.
Neil MG


I did the job just a couple of weeks ago. I needed one litre for just the MGA. I used an eezibleed kit for the first time and found it made the job easy (although my one did have a faulty air valve connector that was a pain but they have now replaced).
I initially removed some fluid direct from the master cylinder with a turkey baster; not too much as you dont want to risk getting air in he system. If I did it again, I wouldn't bother with that. I then started at rear and waited until fresh fluid appeared at each wheel.

Don't forget the clutch slave. The eezibleed displaced some air from that, which I doubt I would have done with the old fashioned method of using her-in-doors in the car.
Good luck
Graham V

Until very recently you could buy coloured (blue) brake fluid which was very useful for a complete fluid change as you just let the fluid run through until the colour change was visible. Unfortunately the commercial standard for brake fluid stipulates the colour so the blue was outlawed. Shame!

Be VERY careful with Eezibleed! If any connection in the unit comes loose it can spray brake fluid everywhere but mainly on your paintwork! It works very well but I always throw an old towel over both the unit and the mastercylinder to give some protection in the event of a leak. Do forget it has 15/20 psi behind it!
Graeme Williams


Done that! Fortunately with silicon fluid. In my case I unscrewed the Eezibleed connector from the MC before disconnecting the pressure feed!

Steve Gyles

The connection that worries me is the one from the top of the eezibleed reservoir to the mastercyl cap. If either end comes off........! Doesn't bear thinking about. And also, as you said Steve, removing the cap without relieving the pressure.
Graeme Williams

I agree, you should cover things up well with rags, etc - I initially had a leak on mc cap. Had to make it very tight to seal
And to add to those words of warning, I remember reading, on the midget/sprite site I think, that some one reported a problem with their steering after using eezibleed.....turned out they forgot to inflate the tyre afterwards!
Graham V

Full tyre pressure is too high for Eezibleed. I deflate to about 10 psi.

Steve Gyles

That is my full tyre pressure Steve - got to soften the ride at the back somehow :-)
Graeme Williams

Thanks to you all for your comments. I too have an Eezibleed, and have had mixed fortune with it - you always seem to get the brake fluid leaking out no matter how many rags you wrap around the m/c - I always have a 4-pint ex-milk carton full of water handy when I use it. I did read somewhere that the two-pack paint is a bit more resistant to the corrosive affects of the brake fluid, but I don't want to put it to the test. But I guess the Eezibleed is the way to go - I will let some air out of the spare wheel tyre before starting, and will siphon some fluid off from the m/c before I start - and thanks also because I had forgotten about the clutch fluid - will have to do that as well!!!
Cheers, AB
A Bennett

I have my own trick with Eezibleed that avoids the mess. It slows proceeding down though. I have the 1600 extension on my MC so there is plenty of capacity in there for doing one brake at a time. Therefore I never fill the Eezibleed bottle with fluid. I just let the MC fluid level drop. After doing one brake I top it up again, wait for it to settle then continue with next brake.

Steve Gyles

Like it Steve - good idea
Graham V

Agree with Graham on that one... great idea Steve.
Graeme Williams

Steve,s method sounds similar to one I use. I bought a very cheap kit ( $12) a long time ago and it just consists of a small bottle fitted with magnet ( to fix to bodywork near and above bleed point) , and a short length of clear hose with a range of push in end fittings for bleed point .I fill up mc , open up the bleed, pump enough fluid, watch bottle a couple of times , until near full to get new fluid in .....close bleed point . ...and move onto next point.
Whole process takes max 10mins.....and no real chance of fluid on bodywork ( plus a big absorbent cloth around mc to allow for unsure hands ....) . Used it on my jeep and other cars.
Neil Ferguson

This thread was discussed between 15/01/2016 and 26/01/2016

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