I am loosing a considerable amount of brake/clutch fluid, I fill it up then 1-2 dys later or 25-40km's later it need filling at least 1/2. It would appear as if the master cylinder is leaking. What are some of the things I can or should check to either stop it from leaking or reduce it. I don't really want to have to replace it if I don't have to. Any tricks or pointers?

does the "vanishing" fluid reach a lower level and stay at the point, or does it completly empty itself?

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real men race downhill - keiichi tsuchiya

if it reaches a certain point and stays there then you have a crack in your plastic fluid housing (assuming you dont have a tin can type)
you can fix it with superglue, or just replace the plastic type.
if it empty's itself then you have a bad leak somewhere, search all brake lines etc until you find the cause

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real men race downhill - keiichi tsuchiya

Is it clutch or brake that's dissapearing ? Check around all the wheel cylinders and pipe junctions if it's the brake and around the slave cylinder if it's the clutch . Also lay on the front floor and reach up under the master cylinders/pedal mechanism and see if it's leaking from inside , they can leak there and not be noticed for a while .

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It the master brake cylinder thats the one that sits up the back on the bulkhead driver side? It empties itself to a point I'll take it off and have a good good and I'll check the brake lines etc. I'll take a look at it this evening after work and let you know what i find.

if your standing infront of the car looking towards the engine bay, the left cylinder is brake and the right is clutch. (if your stting in the car the left pedal being clutch etc)
like we said check for hairline cracks in the housing. wipe it clean find the where its seeping from

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real men race downhill - keiichi tsuchiya

will check it tonight thanks for all your help

Just be wary of letting it run too low, you don't want it to suddenly draw lots of air in and you have no brakes....

As said make sure you check for wet pedals, the master cylinder can leak out the bottom. My clutch leaked like that when I bought the car but it miraculously fixed itself after a while... must have gunked up. Been fine since then!

If no leaks round the MC I'd check the bottom of all the brake backing plates for evidence of leaking. Or better yet pull each drum off for a look. You can check the brake shoes for wear at the same time.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I had a quick look this evening and I tightened the bolts and had a good ole looksee for cracks. So I'll see how I go, if it doesn't get any better I'll double the lines and drums and go from there. Thanks to all the advice given by u all

I noticed my brake pedal was starting to get lower and a little spongey over the past few weeks. Checked the fluid levels and she was only running on half an inch of fluid.

Topped it up on Monday night and seeing how it goes for the rest of the week (checking fluid level each night). If the fluid drops then i definately know there's a leak, if not then i guess it could just be an adjustment or brake bleed.

Either way i'll have to book the car in to get something fixed.

Either -

Dodgy cylidner in the drum assemblies
Leaking/Split Hose
Leaking Master Cylinder
Dodgy hydraulic brake light switch

Do like doc said and take a look inside each drum assembly and check for leaks. One sign is streaks of leaking on the walls of the tyres originating from the centre of the wheel.

Get underneath your dash and check the bottom of the Master cylinder, replace it ASAP if its leaking.

Check your hyd. brake light switch if you have one.

Check out all your hoses under there.

If you braking system is leaking, consider an overhaul. They are too important not to have working. Master cylinder is only about $120, the slaves being about $18 to $30, and hoses are pretty cheap aswell. If I was losing 1/4 my brake fluid every 24-48 hours, I would stop driving the car, as you are risking something just dying completely.

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No more Minis!......For now.