Why bleed all 4 brakes if only 1 component is replaced?

["Turbo-T"]

Just curious here....I had to replace a front brake caliper. I keep reading that all 4 brakes should be bled. I didn't have to open up the rear system. Why would the rear system need bled?

 

[rob350]

I would just bleed the front brakes.

 

[87granny]

Just curious here....I had to replace a front brake caliper. I keep reading that all 4 brakes should be bled. I didn't have to open up the rear system. Why would the rear system need bled?

Because air gets into the system and can be traped and you pushing the pedal can cause the air to travel through the lines

 

[pacecarta]

Because air gets into the system and can be traped and you pushing the pedal can cause the air to travel through the lines

if you're changing out for appearance or simply because you want to because they are cheap and it was not leaking or internally rusted caliper or wheel cylinder you only need to bleed that corner ,

but

if it leaked or the fluid is dark or discolored or cloudy and if theres any signs of rust in the fluid side of the caliper and has been years or you dont know when the last time the system was flushed clean you might as well do all four corners
brake fluid absorbs water which boils and causes air pockets and poor braking and rust because your lines are plain steel and calipers wheel cylinders are cast iron
the powermaster if you want good life from it should have the fluid flushed regularly and fluid should be clear in the reservior , if its black its way overdue to be flushed

 

[twodafloor]

huh?

Because air gets into the system and can be traped and you pushing the pedal can cause the air to travel through the lines

a yeah

 

[turbodave231]

You don't always have to bleed all 4 wheels if you get a good pedal.........however, It is a good practice on classic cars (yes GN's and TR qualify as classics) to replace the brake fluid every few years.

Its a fact that DOT 3 absorbs moisture from the air. The moisture will cause corrosion in calipers, wheel cyls and master cyls.

I pump the PM down and use a syringe to suck out the brake fluid and replace it with fresh DOT 3 every couple years. I like to wipe the black gook out of the MC reservoir while it is empty.

Getting the fluid out of the lines is easy and it keeps the bleeder screws freed up too.

"I'M just saying"

Dave

 

[1quick6]

I agree with the others. I was following your story in the brake section and you have already bled the backs with fresh fluid. I'd still bleed both fronts after replacing the one caliper. Good luck and go by pedal feel to ensure you are truly done bleeding.

As noted, dot3 does need to be changed since it is hygroscopic. I'm sure there are a lot of Turbo Regals out there that have 20 year old brake fluid in them.

 

[chopped39]

Just curious here....I had to replace a front brake caliper. I keep reading that all 4 brakes should be bled. I didn't have to open up the rear system. Why would the rear system need bled?

You only have to bleed the corner you replaced unless caliper was leaking fluid. Fluid should be changed at least every two years. Dot 3 is hygroscopic but its the copper lining in the brake lines that is the #1 contaminant in brake systems.Unless you have stainless lines. If this is the same car that had bleeding problems just do the one wheel because Im sure you ran enough new fluid through it.

 

[whitehot1]

As easy as it is to do why not just bleed all 4 corners?

I open the bleeder screws and let gravity do it's job of removing the old brake fluid from the system overnight once a year. :smile:

I use this one man bleeder kit from autozone to bleed the brakes, i can do all 4 corners in 30 to 45 minutes taking my time doing it by myself.

OEM/One man brake bleeder kit | Brake Bleeder | AutoZone.com

 

[Dabigguy]

It's pretty easy to bleed all the lines and it will help your brake system last longer. I use the Mitivac. It's a one man system and valuable tool to test EGR and other vacuum systems.

Mityvac Vacuum Pump

 

[1quick6]

If you do use a mityvac, put teflon tape around the bleeder threads or you will suck air past them.

 

[novaderrik]

you don't 'need' to bleed all 4 corners after a caliper swap any more than you 'need' to start at the farthest corner when you do decide to bleed the brakes..