1996 C1500 5.7 Bleeding the brakes - Question

[OBS Oregon]

I just changed out my front rotors, wheel bearings and break pads on my 1996 C1500 pickup. According to the videos I have found on-line they have you bleeding all 4 brakes starting with the right rear, then left rear, right front then finally left front. I've done brakes before but don't remember bleeding all 4 brake valves? Is this correct or is there another way without buying fancy equipment.

 

[1998_K1500_Sub]

I just changed out my front rotors, wheel bearings and brake pads on my 1996 C1500 pickup. According to the videos I have found on-line they have you bleeding all 4 brakes starting with the right rear, then left rear, right front then finally left front. I've done brakes before but don't remember bleeding all 4 brake valves? Is this correct or is there another way without buying fancy equipment.

Are you bleeding for a reason? Nothing you’ve done necessitates a bleed.

If you’re bleeding simply to replace the fluid, a “gravity bleed” should do fine and is super simple. Yes, bleed them in the order you described.

 

[OBS Oregon]

Are you bleeding for a reason? Nothing you’ve done necessitates a bleed.

If you’re bleeding simply to replace the fluid, a “gravity bleed” should do fine and is super simple. Yes, bleed them in the order you described

After doing all the work in changing the brake pads, etc.... the brake pedal is mushy and goes almost to the floor. Something it didnt do prior to bringing it in my garage. I just figured it is something that needed to be done?

 

[1998_K1500_Sub]

After doing all the work in changing the brake pads, etc.... the brake pedal is mushy and goes almost to the floor. Something it didnt do prior to bringing it in my garage. I just figured it is something that needed to be done?

You’ve driven it and, unlike before, it’s mushy?

Or is it just “mushy” because you just finished the job and haven’t taken up all the clearance between the new pads and the rotors yet?

 

[OBS Oregon]

Did not get it out of the garage Started the truck and pumped the brakes - didn't feel it was safe to drive. Will try again in the morning but just in case I wanted a second opinion. Not sure if I did something wrong. Thank you for your help,

 

[1998_K1500_Sub]

Did not get it out of the garage Started the truck and pumped the brakes - didn't feel it was safe to drive. Will try again in the morning but just in case I wanted a second opinion. Not sure if I did something wrong. Thank you for your help,

I’m guessing those first couple of pumps were mushy because of the clearance. Start the engine, pump them a few times and they should firm up, same as before you started the job

 

[OBS Oregon]

Thanks.

 

[Schurkey]

HOW did you make room in the calipers for the new, thicker pads?

In general, the worst, most-contaminated, wet, sludgy fluid in the brake system is at the lowest points--the calipers or wheel cylinders.

Did you push the pistons back into the bores, forcing crappy, contaminated brake fluid backwards through the ABS unit?

Or did you pinch the rubber brake hose closed, open the bleeder screw, and blow the contaminated fluid out the bleeder screw as the pistons went back into the bores?

Getting rid of contaminated fluid requires a brake fluid flush; and that's a great idea any time the friction materials are replaced. Clean out the plastic reservoir on the master cylinder, put in fresh fluid, bleed RR brake until fluid runs clean at the RR bleeder screw. It'll take awhile. LR should take a bit less time because the rear brake system should be clean except for the LR split behind the rear brake hose. RF will take awhile, LF about the same. But that only flushes three out of six valves in the ABS unit. To flush the other three, you'll need a scan tool capable of performing the "automated ABS bleed sequence"; the tool cycles the ABS valves and the ABS fluid pump. It gets the air and contaminated fluid out of the ABS unit, but not out of the brake system, you'd have to bleed all four brakes AGAIN to move the air and old fluid down and out the bleeder screws. GM says you need a gallon of fluid to do this properly--half-gallon before the ABS bleed, half-gallon after.

And then you hope there aren't rust particles or other debris trapped in the ABS valves that don't get flushed-out.

 

[Schurkey]

Oh, yeah. One more thing. If the front calipers have gotten stiff (not totally seized, but the piston doesn't move freely) the brake pedal will be perpetually low when you apply the brakes. The low-drag calipers on 5- and 6-lug trucks are especially sensitive to this. There's a third pressure chamber in the master cylinder, that supplies low-pressure fluid at high volume to the front calipers. It's intended to push the pistons up to the rotor, then the normal high-pressure section of the master cylinder forces the pads into the rotor to stop the vehicle. If the caliper pistons get sticky and take more pressure than the blow-off valve for that low-pressure chamber, that gush of fluid never reaches the calipers--it's squirted into the reservoir instead.

 

[1998_K1500_Sub]

Getting rid of contaminated fluid requires a brake fluid flush; and that's a great idea any time the friction materials are replaced.

@Schurkey, very good points above.

Question: Assuming the OP has...

(a) not opened the system to air ingress, and

(b) not caused the ABS system to operate,

is the complete ABS bleed procedure required? I'm speculating that with (a) and (b) satisfied, there's little or no contaminated fluid or particulates in the ABS pumps or accumulators, and since the ABS valves have remained in their at-rest positions (dump valve seated, isolation valve unseated) no chance for particulates to impair them, thus little or no need for a complete ABS bleed.

As most of us know, avoiding the ABS portion of the bleed procedure simplifies the job a great deal, which I'm sure the OP would appreciate as I doubt he has the means to cycle the ABS (I don't).

I'm sure the OP would appreciate the simplicity of a gravity bleed; it's a one-person operation that might do all that needs to be done, here.