[how do i find out my paint code?]

Now i thought my 95 disco was green, but the paint code 575 reads as avalon blue

my eyes must be bad

[Bleeding brakes on 300Tdi Disco (non ABS)]

Dont worry I'm done with it.

[Bleeding brakes on 300Tdi Disco (non ABS)]

He, he ... the hydraulics and aviation bits remind me of another hydraulic brake specialist working in the aviation bussiness that had issues trobleshooting a (what I consider a simple) D2 brake problem not long ago on this forum ...

What do you mean by "What's the fluid properties got to do with it", Mr Hydraulics Teacher?!

You mean none of the properties of a fluid has something to do with the miscibility between that fluid and another? You mean there's no property of a fluid that tells you something about how that fluid wets the surface of a solid? You mean there would be no difference if, in the said 3 hoses configuration, you want to replace the air with another gas, water, brake fluid or mercury?

Come on Mr. Hydraulics Teacher, you must be familiar with those fluid properties.

Mr. Teacher, there are some things you didn't take into account:

1. the history of the trade (automotive, not aviation), what we're talking about in the trade and the tricks of the trade

2. the big picture

1. The trade:

- this method (separate bleeding) was the only method applied for decades and it worked just fine until mass production, optimizing repair times, advanced ABS systems etc

- we're not talking about bleeding a 50 m long half inch thick hydraulic line of a plane, we're talking about a 1m hydraulic line on a car

- there is a trick you can do at the last bleed of a ramified pipe to ensure the last mixed air/fluid bit, although slight chances to be the case, is pushed back past the T and will be expelled when bleeding the other pipe (I'll let you discover it, it's not hard).

2.The big picture:

- although there are some miscibility phenomena where the pipe splits (T piece), this will take place for a limited amount of bleed cycles; that's because of two things:

a.) the pipes are small enough and the replacing fluid is viscous enough (brake fluid in our case) so there's no vertical fluid separation in the pipe

b.) the brake fluid will 'dislodge' (carry away down the pipe to be bled) a limited amount of air; if the air is taken down the pipe to be bled , the missing air must be replaced with something (brake fluid), you can't have vacuum in the pipe (the one not bled yet); let's say you'll have a couple cubic cm of air dislodged (which will be replaced with brake fluid so in the last bleed cycles there will be no air close enough to the junction) and will be all the air that will mix with brake fluid further down the line and in the caliper.

There are two other aspects of the big pictures:

- the amount of air still on the bled pipe

- the amuont of air in the rest of the brake system due to the wetting quality of the brake fluid and the inside surface roughness.

You will always have air in the system, no matter the method used for bleeding, no matter what you do. What's important is how much air is in the system, if it's in an acceptable quantity. 'Cause if you have so much air that you get a 2 cm longer pedal travel it's not good. But 2mm would be considered perfect.

What we were actually talking about was the best method for the original poster to bleed his brakes, not a history of the 'you wanna do it this way brigade' I and many others it seems agree that pressure bleeding will be the best chance of a solution to the issue.

Point 1. Miscibility regarding liquids is not relevant as we are only using one type ' automotive hydraulic fluid (liquid as fluids are also gases). As you 'must' know air and brake liquid are imiscible hence the need to bleed !

Point 2. Aircraft hydraulic lines are nothing like 1/2 inch in thickness but as you are a car 'Mechanic' and I am an aircraft 'Engineer' I will forgive this minor lack of knowledge. And you would not find a 50m long run of pipe as the problem of maintaining a laminar flow becomes more difficult to control over longer runs of stainless steel pipe as used on aircraft, as a more turbulent flow will tend to release the entrained air (caused by the liquid and air being imiscible) giving a less sensitive output force.

Point 3. The big picture. The big picture is that he has tried to bleed the old way using a number of bleed cycles, so maybe he should use the single cycle method of pressure bleeding ! Yes you will probably get a laminar flow but its more consistent when applying a force to the fluid reducing the chance of air remaining. as that pressure will be felt equal at right angles and without loss throughout the system.

Now if the 2 split pipes were the same length then you may not encounter any problems, indeed you may not encounter problems full stop, due to the, as you say, small scale hydraulic system we are dealing with. However liquid will always take the easiest route out !

Now as a spend most of my time explaining Brahms and Pascals to future engineers I really don't want to get in to a Fluid power/dynamics lesson as you seem to want to, I try to explain in simple terms, but theres always a smart alec isn't there ? I can sit and quote theories and mathmatical terms all day but it wont help the chap bleed his brakes now will it ?

Use the Eezi bleed mate it works, and i did it at 20 psi from my spare tyre as the instructions on the box tell you to. Cracked each bleed nipple once and top job, took 15 mins.

Sorry to the other readers for this boring post that is of no real help.

[Bleeding brakes on 300Tdi Disco (non ABS)]

It doesn't make sense as it doesn't happen . Get 3 small diameter clear hoses (about the same inside diameter as the brake lines), join them with a T piece and test with water so see for yourself. It's a matter of superficial tension, fluid properties and the amount of depression the master cylinder can make.

What's the fluid properties got to do with it ?

I teach fliud power (hydraulics) to aircraft engineers and i can assure you that in a split system there is no way other than luck you will dispell all the air without simultaneous bleeding.

It may appear to be air free but aeration ( tiny particles of air suspended in the fluid) will not be removed. This will eventually manifest itself as 'sponginess' or slow operation to give it its technical term.

keeping the fluid under a constant pressure is the only way to ensure complete de-aeration. And even this is not fool proof.

[squeal transformation]

Tried the penny trick yet? - Put a penny behind the tensioner assembly at the 9 o'clock position - solves it 99% of the time.........

You must elaborate on this one ........... behind the unit or the wheel ? How does it work ? Cant be an Aprils fool as its the 2nd.

Cheers

(if it works i owe you a beer)

[Bleeding brakes on 300Tdi Disco (non ABS)]

Just done mine after changing all four rigid pipes to the calipers for MOT.

I bleed using a pressure bleed kit eezi bleed)about £15 to buy and I've used it dozens of times and it never fails, uses the pressure from your spare wheel to force the fluid through.

Problem with the 2 man bleed is where the brake pipe splits at the rear as you bleed one caliper you drag air back in from the other pipe that has not been bled yet ....... does that make sense ?

You cant fail with an eezi bleed kit as all the pipes are pressurised.

If its still spongy after that then you have a leak some where or air can get trapped in the servos, but again pressure bleeding will push this out.

[squeal transformation]

Had the same thing, changed the bearing on the tensioner and it went ........ and came back. Changed the belt it went .........and came back. Changed the water pump and it went for good........ as did the P gasket aaaarrgh.

Well changed the P gasket and guess what .......... the squeals back. Sure its the tensioner again.

[Fuel gauge on 300tdi]

First of all I'd like to say hello to my fellow disco owners, I have had my 95 300tdi auto for about 2 years now, bought it as a mobile skip when I was doing the house up but I have grown to love it and am keeping it..........

So to the point, had to weld the rear floor pan back on so dropped the tank for access etc. Put it all back together and the fuel gauge now seems to move about a lot more than it used to whilst driving (corners , hills ).

I had to put a good splash of juice in initially as the float seemed to be stuck, once 3/4 full it read fine, but it seems to move above and below the level quite a bit, maybe it was doing it before and I'm just noticing it more now or have i dropped the sender and float back in wrong can this happen ??

Thanks in advance

Mark T (very new to the landy world !)