Hi i own a 1998 chevy siliverado and my brakes are not working adequately, im not losing break fluid so im unsure of the problem

If the pedal seems really hard to push, you could have a bad brake booster. If the pedal feels OK but there is not much action from the brakes, there could be an internal leak in your master cylinder. If your vehicle is equipped with Antilock Brakes, it could be a bad Hydraulic Control Unit.

I start checking by stopping the truck quickly on a smooth gravel surface and get out and look at the marks the tires made. If the rear tires grund alot and the front just some, the front need checking. If the brake pads are thick ( 1/4 inch or more) they might be glazed, if thin there's the problem. Turning the rotors will get a new start for the new pads and you'll find it stopps real good, new rotors better still. make sure the caliper bolts and sliding surfaces( mounting) are free or rust and ruffness with the caliper pushed back and it mounted you should be able to move the caliper side to side with just some resistance as the caliper piston should push back fairly easy with a pry tool or a pair or channel lock pliers without much force. if it is hard and you open the bleeder bolt and it's easier, the brake hose or even the brake pedal not returning will cause this to hold the brakes on some while driving and glaze the brake pads and they'll ( afer overheated) become harder and uneffective. If stopping and the pedal goes down quite abit, and you make a few quick pumps of the brake pedal and the pedal comes up higher the rear brakes may be out of adjustment. The rear brakes are suposed to adjust themselves but the adjusters get stuck or the driver seldom stops hard going backwards to acuate the adjusting sequence. after the rear brakes get out of adjustment enough even stopping hard backwards might not get them to adjust but it's worth a try. Find a place where you can back up and not worry about running into anything and drive along backwards pumping the brakes. hit em hard enough to almost lock the wheels as it's the shifting action of the shoes the advance the adjuster wheel. If no good and the brakes still feel like thier puming up. ( Let it sit and hit the brake pedal and it so far from the floor and them pump it a few times quickly and it's farther from the floor) If it does this then the rear brakes will have to be adjusted by hand. remove the wheel and then the brake drum to see what's going on in there. anything you do to one side you must do to the other side. With the drum off look to see if there is enought brake shoe lineing. If it has rivets and all the revits have pleanty to go before they hit the brake drum then your fine just turn the adjuster, ( it can be stuck) till it's tight enought to just touch the drum but not dragging. Whereever you do the other side ( other rear wheel) needs to be adjusted the same way. You might find that the wheel cyclinders (THE HYDROLIC CYCLINDER THAT EXPANDS AS THE BRAKE PEDAL IS PUSHED DOWN) may be leaking a little. Don't let this go. the wheel cyclinders cost very little conpared to brake failure and should be replaced. I pinch the rubber hose from th frame to the rear axel as I replace the wheel cyclinders tokeep all the fluild from getting all over everything and to make it eaier to bleed the air out once the new parts are installed. with the new parts installed and certainly change the wheel cyclinders if your changing the shoes. 98 was a long time ago and if you drive hard and alot this can be a very other year kind of job. If you've never done rear barkes or any kind of brake job before at least have someone who has check what you've done to catch any mistakes you make. It's better to check and be corrected than to drive and wreak.