Break Line Replace/Bleeding?

*Brake*
So today I noticed slight cracking on the front break lines of my 99 prerunner.
Break system has been flushed not too long ago as I had rear axle seals replaced and rear drum breaks completely rebuilt break cylinders and all. SO break fluid is for sure pretty fresh still.
I have flushed and bled break fluid on my street bike before which was very easy.

MY QUESTION

If I remove just the front rubber break lines and ensure the master cylinder doesn’t get too low... Do I need to bleed the entire system including the rears or can I just bleed front Passenger then driver and should be good? I’m curious about this?

 

If the level in the Master cylinder drops to the piston level it will suck air

In theory it should work My luck is never that great

 

As long as you don't let the level get too low, yeah you should technically be fine.

In practice, however, this almost never happens (at least for me) because there's that *one time* you go one pump too many and the fluid dips too far.

Might as well just prepare yourself for a complete re-bleed, lol...

 

When I replaced my brake lines I hardly lost any fluid and I still had to bleed the system because air got into it. Same thing when I replaced my banjo bolts, had to bleed it afterward. I would count on having to bleed it, it's not that hard to do and it's better to be prepared for it than not.

If you bleed the brakes its best to do all 4 corners...start furthest away from the master cylinder and work your way to the front.

 

Did your old line look like this? I just replaced both front lines last weekend on my 99 Prerunner. I've got another line coming to replace the rear line.

I figured it was time to replace 20 year old lines.

 

While that is just a protective rubber coating on the outside of the line, that's still pretty bad.

 

Yeah, I would def make sure it didn’t.

I’m just wondering if I put the new lines on and start the bleed from the rear, would that air in front some how be pushed to the rest of the lines creating a lot of extra bleeding needed to be done At the rears as I work my way to the fronts.

I may just wait until I do the entire suspension and add the rear extended break line and do it all at once.

Yeah mine look pretty similar. Maybe not as bad, because they aren’t being bent like that pic and showing as much cracking, but definitely showing signs of cracking after 20years and almost 240k miles.

 

I think we have a winner right here.