Heavy Brake Pedal Question
I have a 1991 GMC Sonoma, and I am having problems getting the brake pedal to come all the way back up. At first it was just a problem with the lights not going off, but now you can feel the brakes not fully releasing unless you pull the pedal up with your toe. I've never worked on this part of the brakes and would appreciate any advice you can give me.
The truck sat unused for 3+ years (while I did a very slow V8 conversion) and I first noticed this problem when I got it back on the road. I put white grease on the booster pushrod where it comes out of the firewall and that helped for a while. I also tried replacing the brake-light switch, which of course did nothing.
When I listen carefully (and the engine isn't running) I can hear a rubbing sound coming from what looks like a weather packing gland the rod goes into before it goes through the firewall.
What is it that usually causes the pedal to return? Is there a spring inside the booster or the master cylinder? The brakes feel firm and I don't lose any brake fluid, so I'm guessing the master cylinder is still tight.
Thanks for any advice you can give me...I hate to just throw parts at something I don't understand very well.