Cleaning brake lines?

[David Montgomery]

Hi all! My m38 brakes were getting horrible so I decided to check out the brake cylinders. All four were full of dark brown crap, like thick mud... what the heck?? Three wouldn't work at all and on the last only one side provided any stopping effort. Yes, I barely had any brakes. Anyway I'm putting on all new cylinders as the old ones were too rusty inside to even hone out.

Question: What about the brake lines themselves? Might they also have a bunch of that mud in them? Is there a way to clean brakes lines from the master cylinder all the way out to the brakes? Again, what is that thick mud like junk from?

Looking forward to hearing if you folks have seen the same!

Dave

[workingdog]

If you're going to replace all the wheel cylinders (slave cylinders) then it would be prudent if you also replaced the Master Cylinder as well…if you haven't thought of that?

Standard Brake fluid attracts water and needs to be totally replaced at least every year.
To avoid doing that you may like to consider having all your Slave Cylinders and the Master cylinder re-sleeved with stainless steel.
Using Stainless Steel Sleeves ensures you will not get rust in your Slave Cylinders or Master Cylinder.

Once you've done that you can them use Synthetic Brake Fluid (such as Dot 5) and not have the problem of attracting water into the system.
Synthetic Brake Fluid is normally coloured in a Purple colour, so you can see it you spill any….however, it has the added benefit of not affecting your paint should you accidentally spill it on some paintwork.

Under normal conditions…Synthetic Brake will last around 4 to 5 year before you need to renew it. So the initial higher cost of buying the Synthetic is far more economical.

Synthetic Brake Fluid also has a higher temperature tolerance and will keep good braking if you are using your brakes almost continuously…whereas Standard Brake Fluid *can* expand and make your brakes less efficient under constant pedal pressure.
EG. Most motorbikes use synthetic in their systems.

You are also able to store synthetic Brake Fluid in your "spare parts" without having to be concerned that the container will attract water whilst it is on the shelf (even though the top is on).

To clean your lines, first check that the rubber hoses are not brittle, hard or cracked. If they are…replace them.
Once they are OK, then blow all the lines out with compressed air.
Then, load a pressure cleaner with Methylated Spirits and force the Metho through the whole system. {A pressure cleaner that attaches to compressed air}.
Then finally...blow it out with compressed air again, to dry it.
Metho will not effect Brake Fluid.

To reassemble - use a light smear of whatever brake fluid you choose to go with (Standard or Synthetic), on all the surfaces that will have rubber cups sliding up and down.
The old fashioned "Rubber Grease" has quite a few shortcomings and is not recommended nowadays.

Once everything is reassembled, and the system is bled…adjust the brakes and the Master Cylinder.

Oh, by the way, that "mud looking crap" is actually old brake fluid that has gone off due to not being replaced regularly.

[Stoney]

Good advice. I add that Eastwood.com also has Aerosol injector cleaner, part # 12846Z, that you can use to clean out your hard lines. disconnect your hard lines from the rubber lines and blow this stuff through them and then follow with a blast of air. The aerosol can tip fits into the brake line end.

[workingdog]

Good advice. I add that Eastwood.com also has Aerosol injector cleaner, part # 12846Z, that you can use to clean out your hard lines. disconnect your hard lines from the rubber lines and blow this stuff through them and then follow with a blast of air. The aerosol can tip fits into the brake line end.

Thanks.
If you're in Australia you can't get Eastwood products such as you suggested. However, instead of Methylated Spirits you could use ordinary Brake Cleaning Fluid (in an aerosol can).
Either way, whatever you choose to use…Methylated Spirits or Brake Cleaning Fluid…the essential part is to ensure it is all removed from the brake lines i.e. dry and clean, before you feed new brake fluid through the system.