I've recently change the brake lines on my pickup due to rust the lines that were changed are the two that run front the front to the back, into the LSPV.

I started bleeding the lines all fine and dandy until I tried pumping the brakes and there would be resistance but pressure wouldn't build.

I did a bench bleed of the master cylinder and made sure there were no more leaks, which I found there were none.

Starting to think its the LSPV but not sure.

 

Are you saying that the brakes kind of work but the pedal slowly sinks to the floor? Did you bleed the LSPV? If so, and you are getting clear fluid at all the wheels, then it could be the master cylinder. Sometimes bleeding the brakes on an old master cylinder can finish it off, or I have had bad re-maned cylinders, also.

 

Air in brake hydraulic system.

Faulty Master Cylinder.

Incorrectly installed front brake calipers.

 

I haven't tried bleeding the LSPV. Didn't know you could. Maybe I should try that first.

 

It can be as simple as one poor connection or a bad bleeder valve that has a piece of rust.

I have done numerous brake hydraulic rebuilds due to rusted lines my one and only attempt to bleed the LSPV was so very expensive

Then in 20 plus year old vehicles I wonder how many really still work

Living in the great rust /Liquid brine belt is so very hard on brake lines

 

I bleed the LSPV and there was a bunch of air in it. Brakes are fine now. Thanks for the help!

 

Glad you got it fixed.