How to test rear brakes?

[yargnits]

Lucky me, I just replaced the 2 rear brake lines on my 04 Yukon. Yeah, 2 lines because of the active traction control. Can’t say it was fun.

I started with the left side using the vacuum method of solo bleeding. I kept getting air bubbles which could have come from a loose connection or...? I ended up enlisting my neighbor to use the pump and hold method. It appeared to work and I moved to the right side.

Note, using the pump/hold (pressure) method lets you know if you have a leak, and let’s you know where it’s at.

A broke bleeder nipple on the right rear lead to a new caliper. I went straight to the pump/hold method but the bleeding didn’t go as expected. After a couple rounds of good pump/hold sessions, the fluid barely came out when opening the bleeder and the pedal didn’t go to the floor. I then tried with the engine running and got one good pump/hold round before it went back to almost nothing coming out when the bleeder opened.

Could this be the antilock system?

I said a prayer and took it out for a test drive. After driving my car for most of the summer I can’t remember how the Yukon’s pedal felt. Any ideas on ways to test the rear brakes?

I do plan on trying to bleed them again, now that it’s been driven around a bit. I’ll eventually get one of the pressure bleeding systems.

 

[Scottydoggs]

if the master went dry at any point, you need to bleed the master first, via the line nuts, then bleed all 4 calipers.

 

[Fless]

Bleed the farthest caliper first - right rear - then do the left rear. Also, when the brake pedal is pumped, don't push it to the floor; that can do damage to the master cylinder seals. Put a 2x4 or something under the brake pedal to stop full pedal travel.

 

[yargnits]

Scotty, I’m pretty sure the master never went dry. I’m thinking this over. Would the bleeding be acting this way if it had?

Fless, The order doesn’t matter since there are two separate lines going to the back. Both are pretty much the same length.

Good point about not pushing the petal all the way down. I just saw a good youtube video about that... a day after I tried bleeding the brakes.

 

[Doubeleive]

Scotty, I’m pretty sure the master never went dry. I’m thinking this over. Would the bleeding be acting this way if it had?

Fleas, The order doesn’t matter since there are two separate lines going to the back. Both are pretty much the same length.

Good point about not pushing the petal all the way down. I just saw a good youtube video about that... a day after I tried bleeding the brakes.

unless your brake fluid reservoir is dead center in the vehicle and all 4 lines are same length then yes the right rear caliper is the farthest away and it is brake bleed 101 procedure to start with the farthest caliper first, the lines may appear to be the same length but you have to remember the reservoir is located in the front left, so rear right is farthest away. so it goes right rear, left rear, right front, left front.

 

[yargnits]

unless your brake fluid reservoir is dead center in the vehicle and all 4 lines are same length then yes the right rear caliper is the farthest away and it is brake bleed 101 procedure to start with the farthest caliper first, the lines may appear to be the same length but you have to remember the reservoir is located in the front left, so rear right is farthest away. so it goes right rear, left rear, right front, left front.

I respectfully disagree when it comes to the rear lines. I know, I just put them in. Both go from the Manifold under the driver seat, run along the left frame, turn to the center of the truck, transition into two separate hoses, over the diff, then go back to solid lines on the rear axle, at the differential.

I’ll even debate that either rear line is the longest run. It looks like the tubing going to the right front is quite a bit longer than the rear lines. Old “bleeding 101” doesn’t apply to these beasts.

 

[PG01]

I respectfully disagree when it comes to the rear lines. I know, I just put them in. Both go from the Manifold under the driver seat, run along the left frame, turn to the center of the truck, transition into two separate hoses, over the diff, then go back to solid lines on the rear axle, at the differential.

Yes, we understand what you’re saying but it is common practice (for 19,000 years now)to always start a caliper furthest away....which no matter how long you think the lines are, is the right rear. Stop at any garage and they’ll tell you tge same.

On to the bleeding... your abs pump needs to be bled first, then right rear....etc, etc

 

[yargnits]

Yes, we understand what you’re saying but it is common practice (for 19,000 years now)to always start a caliper furthest away....which no matter how long you think the lines are, is the right rear. Stop at any garage and they’ll tell you tge same.

On to the bleeding... your abs pump needs to be bled first, then right rear....etc, etc

So, you’re saying that the direct distance between the MC and the caliper is the only factor in the bleeding order, and actual tubing length has nothing to do with it? I hope not.

 

[PG01]

So, you’re saying that the direct distance between the MC and the caliper is the only factor in the bleeding order, and actual tubing length has nothing to do with it? I hope not.

Hey man, im not arguing with ya, im just telling you what every mechanic from here to Timbuktu will tell you...start with the side that is furthest away from the master, which here, in America, on stock production left hand drive vehicles.... is the right rear.
Have fun bud

 

[yargnits]

I’m just saying the old rules don’t always apply. I was curious about my other thought on the right front and I found this image of a tubing kit. Granted, the lines from the differential to the calipers aren’t shown, but I don't think they make up for the extra length that front line has to go.

I do appreciate the help. I’m just trying to add a bit more thought on the topic.

It’s sad that my truck came from the upper east coast, where they use the most aggressive salt. It’s a freaking rust nightmare under the thing. My plan was to sell the truck this fall, so I’m not going to mess with the front and sell it with the remaining lines in the kit. I am buying a pressure bleeder and will try again when it arrives.

Thanks.


Finger painting on an iPhone isn’t easy, but here are the lines in question.