Brake bleed!

[tfphoenix]

Hello. I was trying to take my X for an actual test drive today but found out pretty quickly that my bleeding attempts had failed somewhere. We had a tough time bleeding the brakes in the first place, we couldn't even get fluid to come out at first so we started with a vaccum pump and eventually got things going with the pedal (had to do this on all calipers) and got A LOT of air out overall. Well after bleeding all the calipers twice with the pedal, the pedal still doesnt feel solid until it nears the floor. Any tips on how to stiffen her up?

Other notes: 86 X, single reservoir, the master cylinder is not leaking, we did not let the reservoir get low when bleeding, we bled in the order of RR, RL, FR, FL both times.

Thanks! :nuts:

 

[Wyverndude]

I hope this doesn't apply to you but...

... I heard a funny story from the guy at the parts counter, who told me that -before he knew any better- he thought it would be a good idea to thoroughly shake his can of brake fluid before pouring it in.

He succeeded in mixing so much air into the fluid that he says it took days and several more brake bleed sessions to get the brakes working normally.

It sounds like you completely drained the brake system at some point prior? If that is the case, you will want to bleed the feed lines from the reservoir to the M/C before starting any bleeding of the M/C or hard lines.

 

[EricH]

reservoir lines

It sounds like you completely drained the brake system at some point prior? If that is the case, you will want to bleed the feed lines from the reservoir to the M/C before starting any bleeding of the M/C or hard lines.

You don't exactly bleed them but you do want to get all the air out of them. I've done this by lifting the passenger(US) side of the car about six inches before I start refilling the system. Remove the reservoir from its bracket and lift it up, and you can get to where the line from the MC to the reservoir is uphill the whole way. Now when you fill with brake fluid there's no way for air to be trapped in the lines. Once you have the reservoir half-full and no air in the lines, put the cap on and put the reservoir back into its bracket.

It's even easier if you use Tygon tubing - transparent so you can see the air bubbles leaving. But don't make the mistake of using vinyl tubing instead of Tygon...

 

[tfphoenix]

hah

well i definitely didnt shake my brake fluid. i removed all 4 calipers and quite a bit drained out but i dont think that would affect the feed line to the mc would it?

 

[Wyverndude]

Yes

Fluid can drain from the reservoir right through the system. If you removed the calipers and left the lines open, the reservoir-to-M/C lines would have drained (given enough time -maybe a couple of minutes).
Not a bad thing, since it's a good idea to entirely replace your brake fluid every so often, but it would leave you with air in those lines; which can be troublesome to get out.

 

[tfphoenix]

well that may be then... i will try thanks!

 

[Jim Young]

When I did my clutch ( similar in some ways )

I unbolted the reservoir and put it up by the wiper (hose on) filled it,, left it overnight(to make sure) to let the air in that line creep up to the reservoir,, and proceded the next day. All went well. It's a first step to eliminate.
Caution :Brake fluid will attack paint..

 

[EricH]

Yes... another way of avoiding grief

Fluid can drain from the reservoir right through the system. If you removed the calipers and left the lines open, the reservoir-to-M/C lines would have drained (given enough time -maybe a couple of minutes).
Not a bad thing, since it's a good idea to entirely replace your brake fluid every so often, but it would leave you with air in those lines; which can be troublesome to get out.

If you're going to open up a caliper (remove/replace hose, replace/rebuild caliper) take the top off the reservoir, lay a piece of kitchen plastic wrap over the mouth, and put the cap back on. The caps are vented, and if you seal them off when the system is open, you won't pull air into the system from the top.

This can be the difference between a major four-corner bleed and a quick pump of the pedal when you're only working with one corner of the system.

Of course, if you're doing a full fluid replacement you want the whole system flushed. Even then, I prefer using a pressure bleeder and displacing the old fluid with new without ever letting air into the system.

 

[Yves]

Brake fluid will attack paint

I use Dot 5 I and have to be not worry with paint attack.

 

[ng_randolph]

single reservoir, <snip> we did not let the reservoir get low when bleeding,

You probably know this, but the single reservoir has two internal chambers. There is a partition between the front and the rear chambers (so that if you have a leak in one circuit you won't drain the fluid from both circuits). It can be hard to see the fluid level in the rear chamber unless you are specifically looking for it. You can drain the rear while at first glance the reservoir looks almost full. Any chance this snagged you during the bleeding process?

 

[Robert Mose]

I learned that one the hard way. :hmm2:

 

[tfphoenix]

uhhhh

You probably know this, but the single reservoir has two internal chambers. There is a partition between the front and the rear chambers (so that if you have a leak in one circuit you won't drain the fluid from both circuits). It can be hard to see the fluid level in the rear chamber unless you are specifically looking for it. You can drain the rear while at first glance the reservoir looks almost full. Any chance this snagged you during the bleeding process?

Also entirely possible. I was unaware of that