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Brake fluid - How old is old


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Hi all

I bought my 3A nearly two years ago and have no idea how old the brake fluid is. The car was restored in 2003 and I presume new fluid was put into the system then.

I have by a series of tests (removal of paint, imersion in water etc) convinced myself that the brake fluid is glycol based. I have just bled the farthest nipple from the master cylinder and was surprised that there were no air bubbles at all. Initially the fluid was a bit darker in colour but that is all.

Is it just bubbles in the fluid that indicates the fluid should be changed? - Should I bother to bleed the other corners.

I have never bled brakes before so would welcome comments from the experienced.

(Out of interest I used a vizibleed kit and it worked fine. )

thanks

Steve

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Hi all

I bought my 3A nearly two years ago and have no idea how old the brake fluid is. The car was restored in 2003 and I presume new fluid was put into the system then.

I have by a series of tests (removal of paint, imersion in water etc) convinced myself that the brake fluid is glycol based. I have just bled the farthest nipple from the master cylinder and was surprised that there were no air bubbles at all. Initially the fluid was a bit darker in colour but that is all.

Is it just bubbles in the fluid that indicates the fluid should be changed? - Should I bother to bleed the other corners.

I have never bled brakes before so would welcome comments from the experienced.

(Out of interest I used a vizibleed kit and it worked fine. )

thanks

Steve

It should really be changed every three years with glycol fluid. Bleeding out all four the way you have been doing is fine starting furthest away from master until each one delivers"clean" fluid. Be careful re-filling your fluid tank and dont let it run out. It would also be a good idea at the same time to do the clutch fluid (integral in the supply tank)

Stuart.

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First, Stuart is right about this.

 

Second, you can check the brake fluid quality. A good car dealer or workshop can test the quality of the brake fluid. Due to the hygroscopic character of brake fluid, it attracts water. It's a fairly easy to test the boiling point: less water in the fluid means higher boiling point.

 

But again, Stuart is right. Better safe than sorry.

 

Menno

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It's not too critical to bleed the clutch - unlike the brakes the clutch fluid won't get that hot so the reduced boiling point of old fluid is less relevant to cluch function.

 

However boiling brake fluid is a little scary!

 

If you are on silicone brake fluid it's still worth bleeding as the droplets of water that condense in the master cylinder tend to gravitate to the lowest point (calipers) and boil at the boiling point of water!

 

Either way brake fluid is to cheap to skimp on!

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It's not too critical to bleed the clutch - unlike the brakes the clutch fluid won't get that hot so the reduced boiling point of old fluid is less relevant to cluch function.

 

However boiling brake fluid is a little scary!

 

If you are on silicone brake fluid it's still worth bleeding as the droplets of water that condense in the master cylinder tend to gravitate to the lowest point (calipers) and boil at the boiling point of water!

 

Either way brake fluid is to cheap to skimp on!

It is necessary to do the clutch fluid on a sidescreen car as the fluid reservoir is common to both with a tube divider down the centre for the clutch and the recommended level is above the divider.

Stuart

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Thanks guys

As it is a sidescreen car I want to do the brakes and clutch as well.

I have done the brakes - no problem using a Vizibleed. Now I am at the clutch slave cylinder but have found the bleed nipple is really tight and I am concerned about applying too much force. As you will know the space around the nipple is a little tight for a normal spanner but I have a spanner with its opening at 90 deg to normal and this will allow rotation if only I could get it to budge. Anyone had this experience??

cheers

Steve

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Thanks guys

As it is a sidescreen car I want to do the brakes and clutch as well.

I have done the brakes - no problem using a Vizibleed. Now I am at the clutch slave cylinder but have found the bleed nipple is really tight and I am concerned about applying too much force. As you will know the space around the nipple is a little tight for a normal spanner but I have a spanner with its opening at 90 deg to normal and this will allow rotation if only I could get it to budge. Anyone had this experience??

Soak the nipple threads in PlusGas. Then try it with a proper brake spanner, if there is room. That won't round off the nipple.

 

Ivor

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You can buy a gizmo from Gunson fairly cheaply - see example on Ebay http://cgi.ebay.co.uk/GUNSON-BRAKE-FLUID-T...93%3A1|294%3A50 - which will give a quick indication of water content in your brake fluid. I've got one and it seems to work ok

 

Yes, that's the one I talked about!

 

I did an All Weather Training Course a few years back. The instructor told us all the usual stuff. Then we went out to the parking and we had to check our cars with this gizmo. My car was 10 days old then, so there was no problem. But... I remember clearly that most older cars had some water in the brake fluid.

 

Menno

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So, I got the perfect spanner ( swivel head with ratchet). It fits easily but still the nipple will not budge. So I will try with PlusGas. I guess using Plusgas here is OK? (I was told not to get any oil type solution anywhere near brake fluid)

Steve

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So, I got the perfect spanner ( swivel head with ratchet). It fits easily but still the nipple will not budge. So I will try with PlusGas. I guess using Plusgas here is OK? (I was told not to get any oil type solution anywhere near brake fluid)

Steve

 

I would not risk it if it was my car. By definition penetrating oil seeps into the components it is on. It is hydrocarbon based so has the potential to destroy the rubber seal. Do not underestimate the trouble making potential. Second only to MRSA I reckon. Even a very small amount may cause the rubbers to swell up. You could try bathing the parts in methylated spirits. I am assuming you are not using silicone brake fluid of course. Meths - alcohol - is what should be used to clean brake internals. It has a fair penetrating property but lubrication is negligible. Worth a try though.

 

After that it is mole grips, which will no dount shear the nipple off. Then it is remove whole assembly to a bench and extract rest of nipple with an "easy-out".

 

Or... If it is just the clutch, take the operating rod off and get someone to very gently press the pedal while you allow the piston to more or less come out of the bore - just to the point of leakage. This is great for lubricating arm pits. Then pop the piston back in properly. If you do it right, it is air free.

 

Nick

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Wouldn't it make sense to just replace the slave cylinder and get on with your life (especially as the weather is so good)? :rolleyes:

You can always try to reclaim the old one as a spare at your leisure.

Edited by BrianC
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Damn right Brian,

 

if the bleed nipple is corroded in that well, the slave cylinder is probably in need of replacement anyway . . . .

 

Hi Nick,

 

Agreed any penetrating oil is not good for rubber seals, but if needs must . . . apply Plus Gas sparingly to the corroded seal with a small paintbrush (as opposed to spraying liberally), give it a minute to soak in, then spray meths from a hand spray bottle to flush off the surrounding area. Another 10 minutes for the Plus Gas to work down the thread and try again with the socket. If it moves, spray liberally with meths to flush off the Plus Gas. If it doesn't move, throw away the cylinder and replace.

 

Cheers,

 

Alec

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