'98 silverado 1500: anti-lock brakes were engaging just by turning the wheel, I replaced;calipers,flex hoses,wheel cylinders,bled them and pedal still goes to floor. Now what?

After taking it for a drive, feel the wheels and see if one is hot. This will indicate that the brake is dragging. A very common issue is the rubber flex hose. The support bracket will rust on the inside diameter and pinch off the tube. The master cylinder will have enough pressure to force the fluid into the caliper or wheel cylinder, but then it will be trapped there holding pressure on the brakes.

If all brakes are locking all the time is not a hose or bad caliper replace the master cylinder.

Hello Patricia,

Have you checked the master brake cylinder reservoir for brake fluid loss?

I don't suspect the master cylinder as you have replaced it... but am more suspect of a leaking brake line or fitting which should have
been discovered when you had the system bled.

The only time I ever had a rear brake problem with a 2500 series Chevrolet was due to seized rear brake caliper guide pins...as your calipers are also new that is not your problem.

If your brake pedal feels spongy and travels to the floor board you have air in the system, a brake fluid leak or a failure in the power steering system, such as a broken hose, broken power steering pump drive belt, or failed pump, would result in a loss of pressure to both the hydro-boost and steering.

Find more information here:

. Hydro Boost Power Assist Systems Operation Diagnosis and Repair

CAUTIONBleeding of four-wheel antilock brake systems require the use a dedicated scan tool.http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c152800c0dbe

Good question, on the antilock system is a bleader too and bleade it the same way you bleade the caliper. After all is done adjust the rear brakes, they should have a drag to them.

If you bleed them correctly,you would have pedal.

You need a helper & the engine running

Did you bleed all 4 wheels?

your power brake booster is blown out
the seal has a leak in it
run the truck for 3 minutes and shut it off. with the windows up listen carefully while you gently apply the brakes
listen for a hissing sound of air leaking.
the sound of these leaking is a very soft sound

You may have a leak in the booster or master cylinder. You can put a pressure tester on the system to test for leaks. It does sound like you have an air leak.
You can try to bleed the master cylinder, then slave cylinder, then brake lines.

Replace both front brake hoses.....they collapse on the inside and will not allow fluid to retract...caliper was probobly fine.....this happens a lot....good luck...Lee

sounds like the flex line is crushed inside alowing the caliper to apply but not release.
The best way to tell is to pump up the brake pedal and get the caliper to lock up. Open the bleeder screw. If the wheel suddenly become easy to turn, the flex line is wrecked. If it is still hard to turn, there is a problem with your caliper.