Technique for draining brake lines

[keiser31]

What do you folks do for a clean or not too messy brake line draining when you start out with new fluid on a rebuild? When you blow out the lines do you use some sort of cover over the ends so as not to blow fluid EVERYWHERE? I would like to know your cleanest technique, please.

[PFitz]

Drain as much of the old fluid as possible  using a rubber tube from the bleeder screws to a can. Flush the system with alcohol drained the same way. Only use low air pressure to dry all the alcohol out of each line in turn into an empty container with a shop rag tapped over the top to stop any risk of splatter. 

 

Paul

Edited July 24, 2020 by PFitz (see edit history)

[C Carl]

Yes, and use industrial grade denatured ethyl alcohol. Or you can also use methyl alcohol if you are working outside, or with very good ventilation.    -   Carl 

[edinmass]

I prefer to use a pressure pot and flush with brake fluid............

[keiser31]

Thank you all for your input.

[C Carl]

Flushing with brake fluid as a cleaning agent is VASTLY inferior to a proper alcohol flush. The reason has to do with water, and any water borne "scum". To remove water and it's fellow travelers, you should use a polar correct solvent into which water is QUICKLY and THOROUGHLY  dissolved. BRAKE FLUID BY DESIGN CAN NOT DO THAT !! HOWEVER, over relatively long time periods, eventually it will absorb a small amount water from the ambient air. This will take place where there is a brake fluid/air interface. The reservoir at the master cylinder. Obviously more problematic in high humidity areas. But it is a slow process. VERY slow. VERY, VERY slow. That is why brake fluid is used in hydraulic brake systems. You quite simply do not want water in your brake plumbing. Therefore, periodic maintenance includes brake flushing. Sometimes recommended as often as every 2 years. Also why the "waterproof" silicone  brake fluid is better yet.

 

Let's see : What more can I say ? Well, alcohol. Earlier, I recommended ethyl and methyl. I have used each. Industrial grade denatured, and U.S.P. grade methyl. They have TREMENDOUS  and UNLIMITED affinity for water absorbency. Can not saturate, or supersaturate at the micro or macro molecular level. But not all alcohols are created equal. Has to do with polarity, so stick with the known solvents for the best cleaning.

 

After sanitizing with a correct alcohol wash, dedicated obsessive types like Ed and you and me can benefit with a power flush with the new brake fluid.

 

Many of you and I have done all this and more to prepare for a change to silicone brake fluid. A perfect time to do so is when you are rebuilding the cylinders and putting new seals in the system. Then, high pressure alcohol flushing of open lines is a MUST. And replace your proportioning valve too.

 

I heartily encourage any real chemist to critique the above, thank you. I am still capable of LEARNING a new trick from time to time. It is the IMPLEMENTATION of those new tricks at the end of a wrench which is becoming increasingly limited and difficult.   -    Carl 

 

P.S. Re-reading this, the next to the last sentence of the next to the last paragraph is not quite complete or detailed. Certainly flush with alcohol, but the pressure to apply is with a thorough blow out of ALL the alcohol AND it's contents with dry air. Leaving any alcohol in the lines to quickly dry does not transport the contamination out. Gotta get the water and scum outta there.   -    CC 

 

 

Edited July 24, 2020 by C Carl
Add P.S. (see edit history)

[Jim Bollman]

When I switched from regular dot 3 brake fluid to silicone brake fluid I rebuilt/replaced wheel and master cylinders and flushed the lines with spray brake cleaner. Not sure if that was the right thing to do. I then blew out the lines with air and let them sit for a few days till I got back to working on the brakes. Seemed to work. Don't remember what I did with the end of the line but probably just slipped a rubber hose over the end and stuck it in a bottle or something to collect the mess. That was over 20 years ago and the brake system with silicone is still going strong. Did a partially tear down to check this past Winter.

[Bloo]

I used to use brake cleaner as well to get the crap out. Lines all disconnected and open, or at least having the pistons and cups out of the cylinders. You really should follow with alcohol (a hose and a small funnel will get it in). Today brake cleaner is different. It does not evaporate quickly. I would be hesitant to use the kind we have today at all. If I did, I would definitely follow with alcohol.

 

I doubt there is a non-messy way. I probably had a shop rag tied loosely over the open end of the line, and a pan underneath. Brake fluid removes paint, so you must be extremely careful if the areas you are working around are painted.

[keiser31]

I will be replacing the master and wheel cylinders, so it's just the lines I will be dealing with.

[DFeeney]

Hello John, I have recently been using the brake bleeder suction system ,  They sell in the $20. range.  I have been happy with how one person can bleed the brakes.  I would guess you could suck about all the old brake fluid out before you used the air hose.   I was also curious with you being on the West coast if you have ever been to  the fall Hershey swap meet.   Stay Safe.   Don

[keiser31]

On 7/24/2020 at 5:14 PM, DFeeney said:

Hello John, I have recently been using the brake bleeder suction system ,  They sell in the $20. range.  I have been happy with how one person can bleed the brakes.  I would guess you could suck about all the old brake fluid out before you used the air hose.   I was also curious with you being on the West coast if you have ever been to  the fall Hershey swap meet.   Stay Safe.   Don

I was raised a few miles north of Detroit and I used to go to Hershey. I think I went four times total. Maybe five. When I tell folks about it, I always say, "it reminds me of ten football fields long and ten football fields wide full of old cars, old parts and people".

Edited July 27, 2020 by keiser31 (see edit history)

[54vicky]

west coast?

[keiser31]

1 hour ago, 54vicky said:

west coast?

Yep.

[Frank DuVal]

Being on the east coast, my method for flushing brake lines is either,:

 

1.Just add fresh fluid to master and bleed at each wheel until it runs clear or,

 

2. Replace everything! Add new DOT 5 fluid to fresh new parts. Yes, I replace the steel lines always, with Cunifer, as they rust out here. Even as new as an 8 year old car. Not fun driving through red lights.....😲

 

To answer first question, I put newspaper down and crack lines open. Do not use your tablet that you read news on, however.....😉  use real newsprint.

[Bloo]

2 hours ago, Frank DuVal said:

1.Just add fresh fluid to master and bleed at each wheel until it runs clear or,

 

Thats what I do. I flush out with new fluid about every 2 years if DOT3 or DOT3. I suck it through the bleeders with a vacuum bleeder until it runs clean. I gathered keiser31 was going in deeper than that.

[keiser31]

Thanks again for all of the tips. It's too hot (100+ degrees) so it will be a while before I get to it.

[54vicky]

On 7/27/2020 at 5:11 PM, keiser31 said:

Yep.

my first clue should have been the lack of white stuff in your postings of spotted cars😁

[trini]

Pardon my ignorance, I am subject to correction. As far as I can tell, brake cleaners are sort of corrosive. It is good for outside use like cleaning brake shoes and backing plates .The rubber dust shield will distort. I do not want to think of the damage to pistons and rubber parts and seal inside.

I have a 1928 Dodge Senior with 4 wheel hydraulic brakes and I am going to flush out the Dot 3,  replace it with the new type what ever it is called. The Master cylinder is at chassis level, well below the wheel cylinder level.

I am getting a machinist to make me a new solid  MC cover, add a pipe in the center , hook a long hose , bring it right up beside the fuel pump. I have a 1 quart capacity oil can  built in the 40"s  . Fill it with good alcohol, and pump it , opening one bleeder at a time .  I am also going to get an extension  for the bleeders onto which I will attach flex lines to put into containers to catch the goosh 

I am 84 years old and still capable of learning something new. I also work alone because I have no help. My wife does not know the difference between a screw driver and a spanner.

[Flivverking]

I would to see acutal documention of a manufacturer or supplier or builder of hydraulic automobile brake systems  advocating the use of alcohol as a flushing agent or introducing anything other then brake fluid in the system for any reason..Just sayin.👹

[Flivverking]

Pardon me...I would LIKE to see documention...