Need Advice on Draining Brake Lines

[tklm539]

Is there a short course in draining (changing) brake fluid in a Deuce.

I have a mix of DOT 3-5. I want to return it to all DOT 5. I read the TM's and posts. I know how to bleed the air out when refilling, but was curious as to the best way to drain the whole system of fluid to start.

Also how much DOT 5 I will need to buy.

Not sure which kidney I want to part with!!!

Thanks

Tom

 

[m-35tom]

a gallon of dot5 seems to be going for $30 and is enough to do 2 trucks

 

[Jones]

Tricky one, Tom. I don't know how to wring every last drop out of a system short of finding a DRY air source and pressurizing the lines then opening the bleeders; but even then you'd still have a little residual in the cylinders and things like fittings, passageways in the master and stoplight switch.
I'd lay in about three or four big cans of fluid and keep the receipt so you can return any unopened ones. I'd be surprised if it took more than that.

 

[maddawg308]

Best source for DOT 5 you're gonna find, $30 for a gallon or so.

www.sprucemtsurplus.com

 

[jasonjc]

Use the bleeder like kenny has and flush with alcohol. Then add your dot 5. Buying it surplus is the best deal around.

 

[houdel]

My advice would be to NOT drain the lines. The military did not do it when they converted from DOT 3 to DOT 5 (aka, BFS, for "Brake Fluid, Silicon"). The reason that draining is not necessary has to do with the colors of the brake fluids. FRESH BFS is a dark purple color. After a fairly short period of time, the color disappears and the BFS takes on a light amber color, the same as DOT 3 fluid. So chances are your brake fluid is all a light amber color.

When the military converted vehicles to BFS, they simply removed any DOT 3 fluid from the master cylinder, refilled with BFS and started bleeding. When purple brake fluid started coming out of the bleeder valve, they were done with that bleeder and moved on to the next. Simple as that, the new BFS was used to purge the lines of the old DOT 3 and the color change indicated when the line was purged. Apparently any minor amounts of DOT 3 not purged by this process were not significant enough to cause any concern.

There is a specified sequence for bleeding, as follows:
First, bleed the master cylinder if it has a bleeder.
Second, bleed the airpack.
Third, bleed the lines, starting with the FURTHEST from the master cylinder, then the next furthest and so on till all are bled.

For all the gory details download TB 43-0002-87, BFS Conversion Procedures, from the technical manuals section.

 

[oifvet]

I just did a roadside replacement of BFS just last week after splitting a brake line en route to the paint shop. My truck was marked "DOT 5" and the fluid was amber. When gimpyrobb and I hooked up his speed-bleeder and pushed fresh purple through, I was satisfied that it was at 90% (+), BFS. My plan is that down the road, (figuratively), I will push the purple through again. From what I understand, a mix of 3 and 5 is not going to shut a truck down by any means. Over time, I will be comfortable with all of the DOT 3 being purged out of the system and DOT 5 in it's place.

 

[acetomatoco]

I have been waiting for years for the mixture of 3 and 5 to cause me a problem... the culprit of course is water....if ya keep that out you are in Vegas..

 

[JDToumanian]

...after splitting a brake line en route to the paint shop.

A rubber line I assume?

 

[oifvet]

The line split at the flare. Just underneath the fitting that threads into the three-way, brass "T" inside the frame where the spare tire is mounted. The flare came off like a little halo! Fluid was spraying like pee-wee after a twelve-pack, (I used to drink beer). Anyway, NAPA delivered a new line and "T" and I did the fix, but couldn't bleed. No pedal, no prime. After a few hours, (broke down at 10:30 a.m., pulled out of the lot at 8:00 p.m.), there seemed to be good pedal, but gimpyrobb was already en route. When we connected his bleeder, it pushed quite a bit of air out. It only took about 30 minutes, and most of that time was spent moving from wheel-to-wheel. It works well!

 

[Recovry4x4]

The bleeder is a must have if you work alone like me and a big + even if you have help. Lee's post was exactly what I would have writtten. My theory on stocking DOT 5 is this. I buy 2 gallons at a time and when the last gallon's seal gets broke, I order 2 more gallons.

 

[tklm539]

Recovery,

Was it you who posted the plans for the homemade power bleeder. I cannot find them now.

Tom

 

[houdel]

Here is the link to Kenny's soon to be patented garden sprayer cum Deuce power brake bleeder:
http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=3439

 

[Recovry4x4]

Thank you Lee!

 

[tklm539]

Thanks