1998 Nissan Frontier brake issues

Hello all, I was looking at this truck on Saturday and I think the brake master cylinder is bad. The pedal goes all the way down, I tried bleeding at master and nothing happened then I went to the back right rear wheel and a few drops of fluid came out with a full reservoir, is like there was no pressure at all, didn’t try all the wheels yet until this week, I ordered a MC to replace it, does anyone has any inputs on this? Is it possible for the abs system to have air in it? If it does, how do I know and how to remove it? I was reading something about a LSV valve not sure if it has it or not or where it would be, how does this work? What bleeding procedure would you recommend? Normally I do, RR, LR, FR, LF, please advise, Appreciate your help

Definitely could be a bypassing master cylinder. It's definitely possible to have air in the ABS system, OR some kind of internal ABS hydraulic issue (though you usually still get pressure at the bleeders).

If you don't get any air out of the bleeders, then I'd suggest making some plugs for the master cylinder ports and installing them. If the pedal is now hard, then the master is fine, and your issue is further down the line. If it still goes to the floor, then the master is toast.

Tyler good thoughts, where would you get these plugs you talked about

There are kits like this one out there, that come with all kinds of plugs for most vehicles:

www.tooltopia.com/thexton-803p.aspx

But usually, when I need some plugs for doing this, I just make them myself. Make a line and nut just like the OE, then cut the line short and smash it closed with a hammer. You can TRY using the plastic plugs that come with replacement master cylinders, but they never seal under pressure, and may even blow out if the master isn't bad. :lol: