Changing front brake pads open bleeder nipple or leave it closed

[ImTod]

Hey all,

I'm planning on replacing the front pads here on my LX here soon but I haven't been able to figure out if its better to open the bleeder nipple on the caliper when compressing the pistons back in, or if its safe to just push them back in which from my understanding pushes fluid back into the master cylinder?

I've seen conflicting information on youtube for it, some saying no issue not bleeding them, others saying you could destroy the master cylinder if you don't. Most of the things I find through search are more focused on rear brakes as that seems to a less simple process than fronts with the parking brake.

Also is it worth doing a full brake fluid flush when replacing just the front pads?

Thanks in advance!

 

[Broski]

Whats the FSM say ?

 

[marques]

I have never opened any bleed nipples when changing any pads and have never had any issues whatsoever. And I’ve changed a lot of pads in my life.

I think the one exception would be if the brake fluid had been grossly neglected (not changed ever in 15+ years), in which case I would simply flush the brake fluid before changing the pads.

 

[marques]

And about the question of when to flush the brake fluid, it should be a function of time (every two years or so), regardless of whether you’re changing any pads or not.

 

[bloc]

I have never opened any bleed nipples when changing any pads and have never had any issues whatsoever. And I’ve changed a lot of pads in my life.

I think the one exception would be if the brake fluid had been grossly neglected (not changed ever in 15+ years), in which case I would simply flush the brake fluid before changing the pads.

What this guy said.

 

[Boston Mangler]

I’ve changed DOZEN of sets of brake pads on all sorts of vehicles and damn near every model cruiser

I do the same method every single time

Usually do rotors at the same time…

-Remove caliper and pads
-zip tie in place so not to put pressure on line
-swap new rotor
-take large C clamp, SLOWLY crank it on OLD pad to compress the piston, again, SLOWLY
-once piston compressed, put new pads in
-slide over rotor
-bolt it all back together

I do this at all 4 corners and check the MC during each corner to make sure nothing overflowing.

I’ve done this method literally dozens of times and it works flawlessly

Then bleed as needed once it’s all back together with new pads

 

[LCH21]

I’ve changed DOZEN of sets of brake pads on all sorts of vehicles and damn near every model cruiser

I do the same method every single time

Usually do rotors at the same time…

-Remove caliper and pads
-zip tie in place so not to put pressure on line
-swap new rotor
-take large C clamp, SLOWLY crank it on OLD pad to compress the piston, again, SLOWLY
-once piston compressed, put new pads in
-slide over rotor
-bolt it all back together

I do this at all 4 corners and check the MC during each corner to make sure nothing overflowing.

I’ve done this method literally dozens of times and it works flawlessly

Then bleed as needed once it’s all back together with new pads

This is what I do. I only change rotors when too thin or damaged. For a simple pad-slap, I don't open the bleeders.

 

[Boston Mangler]

This is what I do. I only change rotors when too thin or damaged. For a simple pad-slap, I don't open the bleeders.

If ya do crack bleeders, replace them with “speed bleeders” been putting them on EVERYTHAANG for 20+ years and make it all much easier and cleaner

 

[ryanCA]

Hey all,

I'm planning on replacing the front pads here on my LX

Which pad are you going with?

 

[TeCKis300]

Agreed, no need to open bleeders.

Couldn't be easier and don't even need c-clamps. You can use the used pads themselves as prys/levers to push the pistons back. Just note that pushing on any piston may extend the other piston(s).

 

[DanielW]

I’ve changed DOZEN of sets of brake pads on all sorts of vehicles and damn near every model cruiser

I do the same method every single time

Usually do rotors at the same time…

-Remove caliper and pads
-zip tie in place so not to put pressure on line
-swap new rotor
-take large C clamp, SLOWLY crank it on OLD pad to compress the piston, again, SLOWLY
-once piston compressed, put new pads in
-slide over rotor
-bolt it all back together

I do this at all 4 corners and check the MC during each corner to make sure nothing overflowing.

I’ve done this method literally dozens of times and it works flawlessly

Then bleed as needed once it’s all back together with new pads

That's the same way I've been doing it for 20+ years

 

[ImTod]

Which pad are you going with?

Planning on just going with OEM based on other threads I’ve read.

 

[ImTod]

Thanks all! This is super helpful!

 

[ryanCA]

Planning on just going with OEM based on other threads I’ve read.

Great, thanks for the info!

 

[tominboise]

I do it like everyone else on this thread. One thing - I suck the fluid out of the master cylinder before I compress any of the pistons. To prevent overflowing the master cylinder. After I get done, I suck out the fluid pushed back and replace it with fresh. Also vacuum bleed the brakes to flush the lines.

 

[bloc]

Just a quirk about our vehicles: there is as much fluid stored at pressure in an accumulator as there is the reservoir, so if the intent is to replace the fluid with fresh stuff, you’ll have to bleed that out into the reservoir as well first.

 

[Boston Mangler]

Just a quirk about our vehicles: there is as much fluid stored at pressure in an accumulator as there is the reservoir, so if the intent is to replace the fluid with fresh stuff, you’ll have to bleed that out into the reservoir as well first.

Good point!

Also good reminder I haven’t finished this portion yet! Oops

 

[NeilC]

I have a mobile mechanic business as a side hustle and, by far, the most work I do is brake jobs. I use a Mityvac to suck out the fluid while I use a ratcheting piston compressor to push the pistons back in. I do this because the fluid in the caliper is exposed to the most heat cycles and its the best way/time to remove the worst fluid. The fluid in the reservoir always looks a lot cleaner than what I pull out of the caliper with the Mityvac. On vehicles that have had a prior brake job, you can absolutely tell if the fluid was removed or not because the fluid will be like black coffee. That being said, in the past, I have simply compressed the pistons and not worried about sucking it out and never damaged the components. I started doing it like this after studying for and passing the ASE brake repair test. It is a little bit extra work but is the right way to do it and will extend the caliper's life in the future.

 

[bloc]

I have a mobile mechanic business as a side hustle and, by far, the most work I do is brake jobs. I use a Mityvac to suck out the fluid while I use a ratcheting piston compressor to push the pistons back in. I do this because the fluid in the caliper is exposed to the most heat cycles and its the best way/time to remove the worst fluid. The fluid in the reservoir always looks a lot cleaner than what I pull out of the caliper with the Mityvac. On vehicles that have had a prior brake job, you can absolutely tell if the fluid was removed or not because the fluid will be like black coffee. That being said, in the past, I have simply compressed the pistons and not worried about sucking it out and never damaged the components. I started doing it like this after studying for and passing the ASE brake repair test. It is a little bit extra work but is the right way to do it and will extend the caliper's life in the future.

In general I’d agree that this is best practice, but it turns into a question of competency. Meaning I usually wouldn’t expect people new to wrenching to be able to juggle all of that without potentially introducing problems. Breaking the process down into discreet steps seems more straightforward for that group.

 

[Boston Mangler]

In general I’d agree that this is best practice, but it turns into a question of competency. Meaning I usually wouldn’t expect people new to wrenching to be able to juggle all of that without potentially introducing problems. Breaking the process down into discreet steps seems more straightforward for that group.

Agreed

I’m also of the mindset or doing stuff like this with as basic tools as possible, stuff I carry with me on trips.

Meaning, if I need to bleed brakes for some reason or another on a trip, I’m not relying on a fancy pants gizmo sitting in my garage.

That’s my odd outlook on my approach to wrenching in general