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MG Midget and Sprite Technical - Replacing brake fluid

I want to replace the brake fluid on the midget.Having had the car for 10 months and not knowing when it was last changed I thought it should be done.

I am perfectly familiar with the procedure for bleeding brakes to remove air but I have never completely replaced the fluid. How do I go about it? I'm sure you don't pump it all out then chuck some more in.
Roger D

I would suck out what's in the M/C, and replace with fresh, then just pump it on through!

If the fluid is really old it will be a different colour to fresh fluid, so as you bleed it through you will see when the fresh fluid starts to come out the nipple.

Or just flush a butt load (a british standard measure) to be sure it is done!

Happy bleeding.
Malc.
Malcolm

Crack open the bleed nipples and let gravity empty the system for you.

Or use a pressure system like EasyBleed, and put plenty through to completely change all the fluid.

I would do the later personally.
Chris Madge

My tip: don't let the level in the master cylinder reservoir get too low or you will risk getting air in the system.
Jonathan Severn

For an unknown system I’d bleed (probably the rears) before topping up until the M/C is almost empty - avoid going too low!
Then I’d top up with fresh fluid and repeat 3 or 4 times but obviously doing all points front and rear. You’ll never completely change the fluid without a full system strip but that way you will minimise dilution with the old fluid and the amount used.

My latest preferred bleeding system is suction using a kit similar to this:

http://www.ebay.co.uk/itm/393420043233?epid=2298257082&hash=item5b99a973e1:g:5k0AAOSwZI1g3WtY

The main advantages are that it is one man operable and if anything goes wrong it isn’t going to explode fluid everywhere like ones that pressurise the reservoir.
John Payne

Same as bleeding brakes but you want to completely empty the system as you replace with new then more to flush out any crap fully at the reservoir and each corner and a bit more for luck and allowing for bleeding air out. Get a litre bottle and don't be stingy with the flushing.

You're trying for the fluid that's in the reservoir (I always clean the inside the reservoir) and that comes out each of the nipples to be the same as the fresh in the new opened bottle.

Don't worry about how quickly you can get the job done or how long it takes you just do a thorough job.

Nigel Atkins

Here are my brake and clutch kits. The brakes usually take two mugs of tea and perhaps three pees.



Nigel Atkins

Roger

If you want to remove old fluid from the master cylinder without flushing it through (before then filling up and flushing the old fluid from the pipes and bleeding out air), I have found large plastic syringes useful (and can attach a tube to the end if needed). You can buy these cheaply from agricultural supply shops - get a number (and label them carefully and keep and use separately, a clean and dirty one and a set for oil and a set for brake/clutch fluid) as handy for removing oil from lever arm dampers, topping up diff oil etc.

Cheers
Mike
M Wood

Thanks for all the helpful comments.
Nigel, I'm a bit worried about your mugs of tea timescale. I can only admit it with total secrecy, I don't drink tea. THERE I'VE SAID IT. I'm out of the closet, please don't think badly of me, I do have other more reprehensible habits.
Roger D

Roger,
at least you are out of the country. I go places over here and get offered coffee! I once bought a workmate a coffee because he insisted, I had to let it go as he was driving and had the keys, it was at a motorway services, I've yet to recover from it or forgive him for it.
Nigel Atkins

This thread was discussed between 08/04/2022 and 09/04/2022

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