Brake pedal on 1978 244DL

[vjck_uk]

I should'nt think that idea has got a hope,you may be lucky and may improve the odds by when it's all conected to push the calipers pistons in as though changing the pads which will force any air bubbles back into the master cylinder but also old fluid.
I personally would'nt bother as it no problem to bleed a completely dry system on your own if you have a home made tool like I have to hold the brake pedal down.
If you look in the Haynes manual it tells you the sequence to bleed the various nipples.
I also use a length of soft rubber pipe with the end blocked off and a slit in the side about an inch long,this acts as a one way valve.
If not then just get someone to give you a hand,always hold the pedal down to the floor when tightening up the bleed screw.
On no account put any of the used fluid back in.
If you are a tightarse and the fluid looks clean then you must let it stand over night before using it with a cover over it, but personally I put mine in the fuel tank of the mower as it smells great just like Castrol R.
Good luck.
Vaughan

[Clifford Pope]

As I said Vaughan, I have sucessfully done this trick on three cars. A garage man told me about it - he said it was standard practice. Volvos are notorious for persistent air-lock trouble in the 'octopus' and in the in-line pressure valves in the pipes to the rear axle after complete emptying.
It takes me about 10 minutes to swap a master cylinder - how long to do a complete bleeding sequence, even if you don't encounter any air-lock problems?

I like the mower tip!

[vjck_uk]

If you have a knackered master cylinder then the fluid could do with changing anyway.
I have bled mine a couple of times once after fitting a new master cylinder and had no trouble at all.
I did it on my own with a home made bleed tube (as in previous post and a home made extendable (from an old klooklock) tool which holds the brake pedal down.
I find that if you hold the brake pedal down on the last stroke from each nipple then you will have no probs at all.
As I said in my other post I don't think your idea has a prayer,but if you want to try then be my guest,but I know which way I would do it.
After being a mechanic for yonks then I will continue to do it this way.
Vaughan

[neil stevenson]

The brake fluid is a horrible gungey brown colour and needs changeing.
However the master cylinder ordered last week has not arrived and I have given up and reordered from another source. It will arrive tomorrow so if it does not snow to much I will fit it tomorrow afternoon.
We will see if it all goes to plan then.

[vjck_uk]

Well that solves the question whether to change the fluid or not.
If you do it like I said you will get no trouble.
Make sure you do each nipple in the correct sequence.
Vaughan

[neil stevenson]

Nobody said it was going to be easy but this would try the patience of a saint.

I replaced the master cylinder and all went well, a reasonable pedal which stayed up under pressure.

However the weather is not great for lying under a car and so I left in to an independant garage to bleed the brakes and change the fluid completely. I even left them in the workshop manual to see in what order it should be done.

They rang some time later to say there was a problem in that they had broken off one bleed nipple, managed to undo two at the front but could not get the other undone and could I come down. When I arrived I was told the car was outside and nothing more could be done, and if I got the nipple drilled out and the others lossened they would be happy to bleed the brakes.

Not a happy bunny but the garage don't want the hassel of fixing it. I would rather do it myself so I know it is done right.

When I drove it home and applied the handbrake the brake failure light came on. So which circuit has the problem? Getting the old nipples out should not be to hard but does anyone know what size they are to replace them.

Do I now have a problem with the brake valve in the primary or secondary circuit.

This started as a simple problem but now it is doing my head in.

[neil stevenson]

Further to my post above.

It seems that the nipples that were undone / loosened off, have upset the pressure drop warning valve. Does this seem right?

If so how do you reset this valve?

It may be easier to purchase a second hand caliper than to drill out the broken off nipple. However my local scrap yard does not have any 240's in at present. Any other model use the same caliper front and rear?

All these questions mean this is a worth while group to belong to.

[vjck_uk]

I tell you I would not trust most garages to bleed my brakes.
As soon as they get a good pedal they would probably leave it at that so you could end up with half the old fluid still in.
There is no lying underneath required just removing the wheels,you've no need to even get your knees wet.

[Clifford Pope]

>I tell you I would not trust most garages to bleed my
>brakes.


I agree. Freeing seized bleed nipples without breaking them is a fine art, involving judicious tapping with a hammer, soaking the threads overnight, very very cautious turning with a good ring spanner, more tapping, etc.

You could try extracting the ends yourself, but I have to say I have never succeeded in extracting anything that has snapped off. Replacement used caliper is the best bet, if you can get one.
You can bleed a caliper by loosening the pipe union, but it is messy, not guaranteed, and won't pump the old fluid out totally of course.

Re-setting the pressure valve is exactly the kind of problem I like to avoid by replacing the master cylinder without bleeding!!!
In theory once everything is bled and working a good stab with the foot should re-centralise it. In practice they often stay stuck. You can try reducing the pressure in one circuit to try and force it back the other way. Otherwise it means dismantling (horribly fiddly) or replacing (more bleeding).

[neil stevenson]

Thanks for the info. I have ordered a pair of rear calipers from Euro Car Parts @ £42 + V.A.T. and a surcharge of £25 each. They should be here tomorrow morning. I just could not see the point of digging around a scrap yard for a pair which may or may not work.

The pressure valve may be more problematical. We shall just have to wait and see. I may get a price for one anyway just in case.

It will teach me to do the job myself next time, although there is no guarantee that I could have got it out myself with out breaking.

The good side is that the car only cost me £150 and last years M.O.T. cost me one new tyre, so this years is the first real money spent, the new parts, discs, pads, calipers, a set of number plates mean I will have doubled the price of the vehicle now.