procedure for replacing brake fluid

[nevets]

this question is not Healey specific but what is the best method for replacing the hydraulic fluid in the brake system (hopefully without the risk of letting air into the lines)? thanks

 

[John Loftus]

I would remove as much of the fluid as possible from the reservoir using a turkey baster or large syrine, etc. Then refill and use a pressure bleeder to run new fluid through the system. You need to check the fluid level frequently and refill to make sure you don't run out in the reservoir. When the fluid coming out each bleed screw looks like the new fluid you have flushed the hydraulic system. Of course this won't be good enough if you are switching to or from silicone fluid.

Cheers,
John

 

[nevets]

thanks John
not switching to silcone fluid.
is there a particular pressure bleeder you like?

 

[John Kuzman]

I use the bleeder from Motive Products. I change the fluid in my "other toy", '69 Corvette, every couple of years using their system. C3 Corvettes have a touchy brake system that tends to suck in air. I built two adapters for my BJ7 and AN5 as well.

https://www.motiveproducts.com/02bleeders.html

John

 

[John Loftus]

[ QUOTE ]
is there a particular pressure bleeder you like?

[/ QUOTE ]

I have a Gunson Eezibleed .. some pictures and description located on the following link. Just make sure you bleed air out of the spare tire you are using for pressure ... it only takes 10-15 lbs of pressure to work:

https://www.enter.net/~rdent/pages/tools.html

If you feel so inclined you can make your own from a garden sprayer (this looks to be the same system that Motive uses)

https://www.bmw-m.net/TechProc/bleeder.htm

Cheers,
John

 

[Johnny]

If your not in a hurry, and who is, I'll pass on a method that my uncle who was a mechanic for over 40 years used to use on his sprint racer that sat for a long time between seasons.
"Remove all brake bleeder screws completely. Let the fluid completely run out on it's own, preferrable overnight, or longer. After all the drips have stopped add more new brake fluid and let that all run out as well. Now, replace the bleeder screws and bleed the brakes to remove the air. I know it sounds to easy, but it does work.
/ubbthreads/images/graemlins/laugh.gif

 

[nevets]

thanks for the suggestion, but I would like to avoid getting air in the lines. maybe I'm missing something but, based on your description, why wouldn't someone simply pump the brake pedel to hurry up the process?

 

[Biff]

I use a simple power bleeder to flush and refill my brakes. It makes it a one person job and will not introduce air into your system. Cost to make it is about $25.00 or less depending on how many of the parts you already have. The plans for it are at
https://www.bmw-m.net/TechProc/bleeder.htm

 

[nevets]

Thanks Biff, that's a nifty unit you made, and a well put together set of instructions...nice work!

 

[Johnny]

Actually I never did it that way myself. I can only say that maybe not wanting to operate the brake master cylinder dry, which would prematurely wear the rubber. You see, if memory serves (and it usually doesn't) with most cars the master cylinders are elevated above the wheel cylinders, thus gravity does all the work. When completely drained (actually the wheel cylinders never completely drain) you just have to add new brake fluid and bleed the brakes as normal. Simple. One person who actually did replace the brake fluid as I said, told me less air was introduced with that method than by pumping or pressure filling. He just removed all the bleed screws, opened the fill can and let it be. Then replaced all bleed screws except the furthest rear one. Then poured in new brake fluid slowly until he saw new brake fluid come out the opened rear most opening. Finally bled the brakes quite easily and was astonished how easy it really was.
/ubbthreads/images/graemlins/thumbsup.gif

 

[anthony7777]

biff,very cool,but ill not be over for thanksgiving dinner! /ubbthreads/images/graemlins/nonod.gif

 

[Ed_K]

I always use gravity to bleed out the old fluid whenever I replace brake pads. I remember how bad brake fluid can get if you never change it. Many years ago, I started replacing all of the brake fluid at the same time I gravity bleed them. A side benifit of using gravity to bleed is that if there are any restrictions caused by an old brake hose, the brake fluid will not come out of the bleeder as fast as the other, non restricted wheel cylinders. You are done when only clean, new fluid without any bubbles is exiting the wheel cylinders.

 

[tahoe healey]

Ed K, do you drain one wheel at a time and if so which is first and which is last (and okay, which of the other two comes first)?

 

[Ed_K]

I always start with the longest run first,( the rear on the passenger side). Then rear driver side. Then passenger side front, and the driver side front is last.

 

[shorn]

I believe the longest run is actually the driver's rear brake cylinder. Although closer to the reservoir than the passenger rear brake as the crow flies (straight line), it is actually a longer run because the brake hydraulic line actually runs down the passenger side of the frame, next to the fuel line. Therefore, the travel is longer to the driver's rear. Whether or not this really makes much difference when bleeding the brakes is uncertain.