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MG MGA - Flushing brake fluid

My brake fluid looks a yucky green so I think I need to flush it out and replenish.
I thought I would buy the gunson Eezibleed so I can do it on my own but would be interested to hear if anyone has good or bad experiences. In particular, does it have a cap that fits our master cylinder. I have a Mk2 so it has a MC extension chamber but I am assuming the screw cap is the same.

I am guessing it is not dot 5 and seem to remember I can test it by seeing if it mixes with water. Am I right in thinking that if it doesn't mix, it is dot 5 silicon fluid, but if it mixes, then it is standard dot 3/dot 4 fluid?

Finally, I think I have to work on brakes furthest from MC first, so by that logic does that mean I bleed the clutch last? I would have thought it makes sense to bleed the clutch first so that I can clear through the MC straight away?

Many thanks, Graham
Graham M V

Graham, I used the Gunson Eezibleed on my car last year with good results. Yes, there is a cap in the kit that fits the MGA master cylinder.
Andy Bounsall

Check archives for "How to tell the difference between Dot 4 and Dot 5" . Gunson Ezi-Bleed works a treat.
Mike Ellsmore

Thanks. So it seems colour is not a guide but I am right about mixing with water, and testing it as a paint stripper is the definitive test!

And thanks for thumbs up on Ezi Bleed, I will buy one today.

Any views on which order I should start, and whether I should do clutch first or last? I guess it is not that important so long as I end up with new fluid at each bleed valve?
Graham M V

Fluids formerly came in all sorts of colours, but AFAIK non silicone fluids now are all clear. Green was Lockeed, amber and crimson Girling, blue ATE.

Suck all the fluid out of the master with a syringe first. The actual cylinders will remain full and no air will get in. Point being to not mix the old fluid with the new.
After that it doesn't matter which system you bleed first.

Near 50 years of doing this, including commercially, and I have never used an EZ bleed or similar, nor seen one in any shop I worked in.
Just keep it full and open one bleed screw at a time, let gravity bleed it until it runs clear.

FR Millmore


If, at the end of the advice others have given above, you are still unable to determine what type of brake fluid you currently have then, in my humble opinion, I think you would be well advised to completely flush your system with something like acetone (or whatever the European Elf and Safety regs allow) which dissolves the glycol gummy residues and removes any trapped moisture. The lines should be dried by blowing with air (ethyl alcohol can also be used, it is not as flammable and won't injure paint). All flexible lines and seals should be replaced so that all rubber that has been exposed to glycol or other contaminants are removed. I think it is highly likely that Silicon fluid got its bad name when owners converted to silicon without carrying out the process. Not sure of the implications when going the other way, but it makes sense to me to avoid cross contamination.

The braking system is your life, so you can never be too careful.

I copied the gist of the above process from an article written by Derek Stevson for the MGCC Safety Fast magazine in 1999. The full article appears on the MGCC members web area - worth a read.

Finally, Silicon fluid normally comes with an identification tag that you can attach near to the top up point. No guarantee that all silicon users use the tag, but I do and have seen it on other cars.

Steve Gyles

Thanks Steve
I am pretty sure I will find out it is glycol based and am very anxious not to reignite the religous war on brake fluids!
But just for the record, I did stumble on another advantage of silicon fluid that to my knowledge, hasn't been mentioned before.
As you will see from about half way down the article below, this type of total brake failure is limited to just glycol fluid!

Graham M V

Oh my gawd. I have often ended up with a mouth full of brake fluid when lowering the MC level after an Eezibleed. Glad I use silicon!

Steve Gyles

This thread was discussed between 25/04/2012 and 26/04/2012

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