Topic: Brake System Flush


sarahcecelia    -- 11-16-2019 @ 4:58 AM
  My front right wheel cylinder was leaking and I replaced it. It had a brownish sludge on the side that was leaking.

When I opened the master cylinder to "top off" the fluid before bleeding, It was empty, showing just a little wetness of fluid, and looked just a "little bit" dirty. I think I need to flush the entire system to ensure that it is clean before adding new fluid.

I read on this forum where a guy used denatured alcohol to flush his system. Would this be a good thing to use? If not, what could be used to flush the entire system before refilling with new brake fluid, and bleeding?

Regards, Steve Lee


trjford8    -- 11-16-2019 @ 8:51 AM
  If your master cylinder was empty and you could see some rusty muck inside you should rebuild the whole system. I would flush the lines with new fluid first and then check all the cylinders as they probably have rusty residue in all of them. Get new cylinders if the old ones are pitted inside or rebuild them with kits if not pitted. Also rebuild or replace the master cylinder if needed. Better to be safe than sorry.

This message was edited by trjford8 on 11-16-19 @ 8:53 AM


TomO    -- 11-16-2019 @ 8:59 AM
  I agree with Tom. In your situation, I would also replace all of the rubber hoses in the system as they are likely to contribute more sludge to the fluid.

Denatured alcohol should be used to flush the lines when you change from DOT3 ,4 or 5.1 to DOT 5 (silicone) fluid.

Tom


sarahcecelia    -- 11-17-2019 @ 8:36 AM
  I saw no rusty muck in the master cylinder, just a very "LITTLE" rusty color on the bottom, but not enough to worry about.

Regards, Steve Lee


therunwaybehind    -- 11-17-2019 @ 11:20 AM
  I had read that "brake fluid' was an ether in the 50's. It surely smelled that way. I will have to try to find out more about the formulation from chemist sources if the service bulletins do not specify an exact formula. The recent concept of flushing your brakes regularly to alleviate the hygroscopic nature of brake fluid sure seems like a property of alcohol. Off to the races! Twice a year! flush and replace the brake fluid with Ford fluid. OPR 3833 pg. 501 in the Ford V-8 1938-40 Service Bulletins not in the 1941-48 Bulletins where Subject 3000 is off on steering issues. Still seeking the actual generics.


ford38v8    -- 11-17-2019 @ 11:39 AM
  If all you saw was a very "LITTLE" rusty color, then I'd guess that for the present time, you'd be just a very little safe to ignore it.

Alan


therunwaybehind    -- 11-18-2019 @ 4:32 AM
  Now that I have read up on recent brake fluid guidance this seems too casual to me. Propylene glycol (not ethylene glycol as used for antifreeze) is available from drug stores and is used for flushing humans before colonoscopies. It would seem to be more compatible with DOT 3,and 4. which are ether based. DOT 5 is a different chemical formulation not compatible with anti-lock brakes so no real problem with classic cars. DOT 2 was a formulation of castor oil and ethyl alcohol. I appreciate those who would use DOT 5 to save the paint if they expect mess but cautions are that in the air it can cause fish eyes in paint while spraying. See also military uses of DOT 5 where anti-lock brakes are only on airplanes with dynamic hydraulic systems of up to 10,000 psi on B-1's. see also my post on not adjusting the brake rod too tightly to the cylinder for why the bypass valve to recycle the fluid back to the reservoir might cause a dry reservoir even when there was still fluid in the master cylinder bore. (More stuff in the Service Bulletins)

This message was edited by therunwaybehind on 11-18-19 @ 4:35 AM


37RAGTOPMAN    -- 11-18-2019 @ 2:42 PM
  HI
I went to VALVOLINE synthetic brake fluid years ago, and never has any problems.
it does not harm the paint finish,
check this out, read the label to see what exactly what this is. next time in the auto parts store,
my 2 cents 37Ragtopman


TomO    -- 11-19-2019 @ 9:23 AM
  If you found "rusty muck" in one wheel cylinder, it very likely that there is corrosion and corrosion products in the rest of the system.

It is your car and your life, so you can do what you want with it. I don't live in FL so I won't meet you on the road.

Tom


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