Bleeding brakes before changing brake pads?

[gibsonj]

My experience was on a 2011 KR. I can't say whether speed of compression had anything to do with it or not. But, I usually compress with a 6 inch C clamp, and that is typically not a fast process. Not taking any more chances now, I hose-clamp the brake lines to minimize back pressure, loosen the bleeder, then compress the caliper. Reversing that order after pad replacement, I've never had air issues that required bleeding.

 

[theoldwizard1]

So, I have been binge watching FordTechMakuloco on YT and came across a video where he recommends bleeding the brake caliper before compressing the piston on "every car, every model year" when doing brake pads. Apparently the concern is that the ABS hydraulic control unit my get damaged if you send old fluid back into it (?).

I've done many, many brake jobs on family cars (all equipped with ABS), including my old Explorer, and never had any issues with ABS by compressing the caliper pistons.

Same here !

The reason I don't do it is because out here, with all the salt and calcium on the roads in winter, the bleeder nipples become literally fused to the calipers with rust and snap off each and every time you put a wrench on it on any car/truck over 5 years old. I once soaked a bleeder nipple in PB blaster for a week and when I went to remove it, it snapped right off... like clockwork.

HEAT is the only solution.

You have to be careful with your propane torch. You want just enough to help free that bleeder screw but not enough to damage any of the "rubber" parts or boil the brake fluid.

 

[TobyU]

Same here !


HEAT is the only solution.

You have to be careful with your propane torch. You want just enough to help free that bleeder screw but not enough to damage any of the "rubber" parts or boil the brake fluid.

I have only heated one up once or twice in my entire life. Probably snapped off two or three bleeder screws in my life also. Maybe only two. I've done a lot. It takes multiple sprays with generous amounts of PB Blaster over at least a few minutes to a few hours. I always soaked in at least three or four times. I just opened 4 bleeder screws on two different vehicles and the last week or so. Three were on a 98 Buick LeSabre that have been sitting for 4 years and the other was on a 93 Chevy truck I have been sitting for about 3. These vehicles were parked outside on asphalt and have a good deal of rust underneath them. Rusted out brake lines is why I was working on them. I use PB Blaster and a 6 point socket on the end of my quarter inch drive ratchet and bumped it with the palm of my hand instead of just pulling. Not one snapped off.
If I have one that's tighter than that and I'm afraid it will snap off I hit the end of the bleeder screw with a hammer five or six good times before I resort to heat.

 

[atrident]

Why send old fluid back up the line if you don't have to.

 

[WakeZone]

I used to compress the fluid back up into the master cylinder and have never had a problem, but I started bleeding calipers about 10 years ago. The idea of bringing fresh fluid into the heat cycled zone is solid. Another benefit is that it excercises the bleeder screw and prevents seizing from long term neglect. Brake fluid loves to absorb moisture. If you live in a humid area like I do, you'll probably need a full flush at some point to prevent spongy brake feel; those screws will have to be broken loose. Extracting broken bleeder screws is not my idea of a relaxing Saturday afternoon.

 

[rjdelp7]

Expedition have 4 piston front calipers. When you crack the bleeder, it is much easier to compress them and evenly. It puts fresh brake fluid in the caliper, where all the work and heats is. I can see why mechanics, like doing it this way. Less tools to pull out and maybe(if everything goes right), quicker.

 

[ExplorerTom]

I just did my brakes this weekend. I bled the calipers just like in the video. The fluid was NOT clear like the stuff I put in the master cylinder......

Seems like solid advice to me. I think I’ll do it like that from now on.

 

[UniqueTII]

I had this exact bad experience. Compressing the caliper put too much back pressure on the seals in the hydraulic control unit. Result was sticking calipers that wore out pads very quickly. Problem only solved after replacing the HCU. An expensive part and a mistake I learned from.

I've got a brake pedal that sinks to the floor after changing pads and rotors and the HCU is a likely culprit, unfortunately.

 

[coupe11]

Never thought about opening/cracking the bleeder valve to compress the piston for new pad installation.

I have bled the brake system to get old/nasty fluid out and new fluid in the system.

Now I'm thinking that doing the bleeding when compressing the piston might be a better way to do it. I'll be replacing the rotors/pads/e-brake shoes on my 2014 Expedition this fall. I'll try to remember to try this "new way" of doing it.

 

[07navi]

Never thought about opening/cracking the bleeder valve to compress the piston for new pad installation.

I have bled the brake system to get old/nasty fluid out and new fluid in the system.

Now I'm thinking that doing the bleeding when compressing the piston might be a better way to do it. I'll be replacing the rotors/pads/e-brake shoes on my 2014 Expedition this fall. I'll try to remember to try this "new way" of doing it.

It's not new, I did it on all 50+ vehicles, just close it when as soon as you compress so the pistons stay there and don't let air in.