Further Brake Woes..! - Alfa Romeo Forum
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(Post Link) post #1 of 9 Old 4 Weeks Ago Thread Starter
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Further Brake Woes..!

My RHD standing pedal dual circuit master cylinder (of unknown age) started leaking last winter and I replaced it with a refurbished one in March.

After about 100 miles, this one started leaking, so I sent it back. It has been rebuilt and tested again so Iím about to reinstall it.

Apparently the company who refurbished it said there was some debris in it/the system which compromised the seals.

With this in mind I want to ensure there is nothing in there before this one goes on. Iíve noticed some specs of grub in the reservoir which has appeared since I washed it out the other year as part of installing new servos and changed the flexible lines.

It isnít magnetic so Iím assuming itís rubber but itís so fine I canít be sure - I used Cohline 2337 for the reservoir to solid lines so doubt itís that - does anyone have any other guesses or am I being paranoid?

Thanks,

Alex
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(Post Link) post #2 of 9 Old 4 Weeks Ago
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I've not heard of the rubber degrading like that in such a short time? Maybe the seals in the cylinder were at fault? Could you remove as much fluid from the reservoir as you can and refill?

If your bleeding the system again why not buy another length of pipe from the reservoir to the metal pipe?



Quote:
Originally Posted by Alex_P View Post
My RHD standing pedal dual circuit master cylinder (of unknown age) started leaking last winter and I replaced it with a refurbished one in March.

After about 100 miles, this one started leaking, so I sent it back. It has been rebuilt and tested again so Iím about to reinstall it.

Apparently the company who refurbished it said there was some debris in it/the system which compromised the seals.

With this in mind I want to ensure there is nothing in there before this one goes on. Iíve noticed some specs of grub in the reservoir which has appeared since I washed it out the other year as part of installing new servos and changed the flexible lines.

It isnít magnetic so Iím assuming itís rubber but itís so fine I canít be sure - I used Cohline 2337 for the reservoir to solid lines so doubt itís that - does anyone have any other guesses or am I being paranoid?

Thanks,

Alex
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Quote:
Originally Posted by roony View Post
I've not heard of the rubber degrading like that in such a short time? Maybe the seals in the cylinder were at fault? Could you remove as much fluid from the reservoir as you can and refill?

If your bleeding the system again why not buy another length of pipe from the reservoir to the metal pipe?
Thanks for the reply - Iíve emptied the reservoir and had a good look at the contaminants and think theyíve come out of the tyre when Iíve been using my pressure bleeder connected to the front wheel.

Iíve sucked them all up and will flush a couple of hundred ml of fluid through to ensure theyíre all out of the supply lines before I put the new MC on.

Iím using a vacuum bleeder this time!

I canít get the flexible lines off as installed then while the servos were out and now remember heating them up with hot water to get them on. Iíll cut them off if I get any further issues, but canít believe the particle size of debris Iím seeing would compromise a seal in the MC - suspect the supplier was covering themselves saying dirt in the system was the cause of the premature failure, especially since seeing the colour of the fluid which came out of the MC following, presumably, their pressure test...
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Perfect.

Does you system bleed ok? I had a mare when doing mine....What process do you follow?




Quote:
Originally Posted by Alex_P View Post
Thanks for the reply - Iíve emptied the reservoir and had a good look at the contaminants and think theyíve come out of the tyre when Iíve been using my pressure bleeder connected to the front wheel.

Iíve sucked them all up and will flush a couple of hundred ml of fluid through to ensure theyíre all out of the supply lines before I put the new MC on.

Iím using a vacuum bleeder this time!

I canít get the flexible lines off as installed then while the servos were out and now remember heating them up with hot water to get them on. Iíll cut them off if I get any further issues, but canít believe the particle size of debris Iím seeing would compromise a seal in the MC - suspect the supplier was covering themselves saying dirt in the system was the cause of the premature failure, especially since seeing the colour of the fluid which came out of the MC following, presumably, their pressure test...
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In the good days when you bought a master cylinder it came with instructions. ISTR you are supposed to loop the outputs into the reservoir and pump until all the bubbles stopped, which seemed to take a very long time. I always do this now when fitting a new one, but I can't positively say bad things happen if you dont do it.
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Quote:
Originally Posted by roony View Post
Perfect.

Does you system bleed ok? I had a mare when doing mine....What process do you follow?
Iíve been lucky and unlucky in equal measure so far! The best technique Iíve found is to fill the MC on the bench through the bleed nipple and rear circuit outlet, then spin it around and inject more fluid through the bleed nipple with the front circuit open until fluid come out of every orifice, then put the plugs back in install the MC, fill the reservoir and then hook it up reservoir lines first.

I then bleed the MC nipple again, then start at the left rear, right rear, left front and finish with right front and a quick bleed on the clutch slave while Iím in the vicinity and covered in fluid! The proper route is opposite corners but Iíve found back then front is fine.

Iíve been told by several reputable sources that bleeding with the engine running is more effective, but am not sure if this applies to using a vacuum/pressure bleeder or just the old school two man approach.
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Quote:
Originally Posted by alfahaze View Post
In the good days when you bought a master cylinder it came with instructions. ISTR you are supposed to loop the outputs into the reservoir and pump until all the bubbles stopped, which seemed to take a very long time. I always do this now when fitting a new one, but I can't positively say bad things happen if you dont do it.
Do you do this on the bench or on the car with tubing? Any new techniques suggestions are appreciated!
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(Post Link) post #8 of 9 Old 4 Weeks Ago
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Quote:
Originally Posted by Alex_P View Post
Do you do this on the bench or on the car with tubing? Any new techniques suggestions are appreciated!
I always assumed they meant on the car, but maybe on the bench would work too, just a little more messy.
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(Post Link) post #9 of 9 Old 3 Weeks Ago Thread Starter
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Replaced the front brake light switch today which was easy (once Iíd found a 22mm spanner), the old one looked like it had either a very mangled plastic washer or a bit of sealant on it - the new one from CA didnít so hopefully it wonít leak; I tried not to over-tighten it but nipped it up what felt right.

The rear one is a different story - itís over an inch so Iím guessing 26mm - and Iíll have to use an adjustable to get it off so wanted to ensure the new one will fit first! Has anyone seen one of these and successfully replaced it with a 22mm version?

Iím ready to put the MC back on and get the system bled, but never want to mess with it again so would like to know both the switches are working first!
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