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Brake Fluid Bleeding
http://www.international2cvfriends.com/forum/viewtopic.php?f=7&t=3911		 Page 1 of 2
Author:  pavlos_k [ May 2nd, 2012, 3:43 pm ]
Post subject:  Brake Fluid Bleeding
Guys the endless problem is here with you again.

This time i have a lhm bleeding difficulty. The problem started after the new master cylinder. After i installed it to the car i blew in the pipes for the pipes to get cleaned. ANd after that i am trying to take the air out but it seems impossible.

The problem i think is a very slow return of the master cylinder . So it is kind of impossible to pump lhm into the pipes and the whole system.

I dont know what to do . I am pumping the system yesterday all day long and tommorow all morning.

A few minutes ago i understood that there is no possibility of success.

So i am coming to the point . Why is the pistons of the master cylinder returning so slow? is there any tip for blleding the air out of the system? I tried to put lhm from the drum brakes but it seems impossible to as the these little air screws doesn t fit well so if i untight them the air and lhm doesnt pop out from the whole but around the screw .
Author:  2CViking [ May 2nd, 2012, 9:04 pm ]
Post subject:  Re: Brake Fluid Bleeding
It is not unusually for a dry master cylinder not to work immediately. The master cylinder should not be pushed to the end as the dry seals can be damaged in doing so.

Best is to bleed the master cylinder before attempting bleeding on the calipers and rear brake cylinders. Fill the LHM container, fit one 8 mm bolt where the rear pipes are attached. Without the brake pipe to the calipers, gentle push the pedal with your hand but not to the end. When LHM are flowing from the front pipe connection fit another 8 bolt, remove the 8 mm bolt from the front of the master cylinder (rear pipe connection) and again gently pump the pedal until steady flow is achieved. Now the master cylinder should be free from air. Leave bolt in the master cylinder on the front (rear brake connection) fit the pipe running to the calipers (remember green seals 3.5 mm) and bleed the front brakes. When done, remove the last 8 mm bolt, fit the pipe and bleed the rear brakes, several times moving from side to side until no more air is visible. Do the front calipers one more time and job should be done
Good luck
Let us know the result. As you can see, this job is a 2 man operation
Author:  pavlos_k [ May 2nd, 2012, 10:58 pm ]
Post subject:  Re: Brake Fluid Bleeding
ohhh !!!! peter . I should asked before doing .......! As i can understand at this point i destroyed the dry seals .....!!!!

My stupidity keeps costing me money ...!

Ok after the first shock this is how it goes.

On monday i got my 2cv out for the first long term testing ( 10km) On the way to the gas station which is a lot of down hill all things were going perfect . After the fuel up then i moved the car for 700 meters and then the car stopped. It was like i was pressing the pedal and the wheels were blocked. So i ordered some tools i shorted the the screw that press on the master cylinder pistons and then the car was ok. So i understood there why the book says that you have to keep 1-1.5 cm play of the brake pedal.

After htat i though that it was a good time to do the bleeding . Untill that time the brakes were working perfectly unless that matter with the blocked pedal and cylinders which i thought that it wwas the wrong play that i ve left on the pedal and the big amount of air in the system.

Now From yesteraday i try to bleed the brakes with no success. The problem is that i ppushed the pedal until the end several times.

At this time i ve disconnected all the pipes from the master cylinder and i ve found thatthere is something strange on the end of the pipes.

ImageImage

I am thinking that the end of the pipes is too long so it cant seal properly the pipes

Please take a look at the photos at the end of the pipe and tell me if you think that it is everything ok.

Thanks Viking for the reply . I ll do it tommorow hoping that the seals are still good......!

I ll let you knowo

Have a nice night guys.
Author:  ken [ May 3rd, 2012, 12:46 am ]
Post subject:  Re: Brake Fluid Bleeding
pavlos,
there's nothing wrong with that brake pipe, there should always be 'about' 3 to 5mm projecting beyond the rubber seal.
By the way, do not overtighten the brake pipe nuts, 0.8 kgf.m. is sufficient.

Have you tried bleeding the brakes since adjusting the master cylinder pushrod to give the correct free play?
With insufficient free play, it would have been impossible to bleed the brakes.

You should also remove those bleed nipples on the rear brakes and clean them out, a small piece of wire plus compressed air should work, otherwise buy some new ones.

I'm not too sure that your master cylinder would have been assembled 'dry', as the correct practice when rebuilding brake parts such as calipers, wheel cylinders and master cylinders is to lubricate the seals with brake fluid before installation.
However, if the secondary piston on your master cylinder is sticking, tapping the end of the master cylinder with a small hammer will often free it off.

ken
Author:  pavlos_k [ May 3rd, 2012, 6:44 am ]
Post subject:  Re: Brake Fluid Bleeding
ken yesterday i fixrd the rod before i start the bleeding process.

and yes i blew through yhe nipples and they are free and. clear.
Author:  pavlos_k [ May 3rd, 2012, 5:43 pm ]
Post subject:  Re: Brake Fluid Bleeding
Ok guys things doesn't look good. I didnt start the bleeding progress as a friend of mine stop by to take a look. The first thing he asked me was why the piston of the cylinder doesn't come back. So i took out the master cylinder to check what is going on .

Now what i am seeing is that the pistons cant come back. Holding the new and the old master cylinders side by side i can see that there is a problem in the new one.

THe old one is moving nice even by a finger pressure and when i ll leave it it comes right away back .

the new one cant move not even by my hand and a rod.

SO i am quessing that i managed to do some serious damage to the master cylinder :evil: :evil: :evil: :evil: ....! THat mIGHT happen when the car's brakes blocked and the car has been stopped whhile i was trying to push the pedal back to its normal situation.

Or some garbages or small dust get in the master and did some damage. So now i am coming to the conclusion that i need new seals or a new master cylinder ? What do you guys think...!

I should get married with a daughter of a mechanic. Ormaybe sell the car before i destroy it .

Anyway what's ur vote on; seals or new master cylinder...?
Author:  2CViking [ May 3rd, 2012, 7:23 pm ]
Post subject:  Re: Brake Fluid Bleeding
Place the new master cylinder upright in a vice. Pour LHM in to the back, let it soak a little, push the piston gentle to see if the piston will return. If not, remove the clip holding the piston in place and withdraw the piston, watch out for the spring. If all fail, ship it back to me.
Cheers
Viking
Author:  pavlos_k [ May 3rd, 2012, 9:26 pm ]
Post subject:  Re: Brake Fluid Bleeding
Thanks Viking for the tips. Already done them . The piston seems to move difficult even when it is pussing. Put some lhm on the back but it doesnt seem to help either. Took it to a friend of mine who is a mechanic told me what i was thinking as an option. Something ( rubber i think from the overtight ) got into the piston and this is the most reasonable explantation.

Anyway i tried to take out the piston but i broke the drill in. So now i am kind of confused . I cant find anyway to take out the broken drill and even if i could manage it this tip with the drill is something that i cant do .

To ship it back is not an option trough to overpriced shipping costs of the greek posts and courier company.

I ll try again tomorrow . If i ll succed i ll ask you to ship some new sealings . If i wont be able to do so i ll buy a new master cylinder.

The 2cv is standing 4 weeks now. Today my sharan tdi is for service and i dont know if i ll take it tomorrow and my aprilia smv has some cables cut out and the the exhaust hanging.

I asked from my family to take away all of my vehicles even the bikes as it seems that the moon is not on my side these days.....! :(

And a question . Why do you put the quote after the text and not before.

2CViking wrote:
Place the new master cylinder upright in a vice. Pour LHM in to the back, let it soak a little, push the piston gentle to see if the piston will return. If not, remove the clip holding the piston in place and withdraw the piston, watch out for the spring. If all fail, ship it back to me.
Cheers
Viking
Author:  J-dub [ May 3rd, 2012, 10:58 pm ]
Post subject:  Re: Brake Fluid Bleeding
Have faith
Author:  2CViking [ May 4th, 2012, 8:21 pm ]
Post subject:  Re: Brake Fluid Bleeding
Don't get it. What did you have to drill to get the piston out?
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