Replaced Master Cyclinder, Bleeding rear brakes.

Hey guys. I have some questions regarding my recent brake job. I've read a few different threads that gave me some information, but nothing that linked it all together.

Like the title says, I've replaced the Master Cylinder on my 1998 4x4.

I'm lifted 3 inches. I'm running the Toytec/Eibach springs in the front, and the All Pro Off Road Standard leafs in the back with all Bilsteins 5100s all around.

Here my issues. Don't know if any of these are related.

1) After replacing the MC, sometimes when I brake, the e-brake light comes on for a split second. More common when braking in reverse. It didn't do this before. The brake fluid is sitting directly between the min & max level. So it's not full, but it's not empty.

[Q] Can a few millimeters of brake fluid cause this light to come on when braking or is my e-brake sensor going bad. Or did I mess something up replacing the MC?


2) I bled the brakes in order RR, LR, FR, FL. The fronts bled fine. But the rears would bleed out during the first two tries, and by the third, the steady stream became a drip...drip...drip. Like the rear ran out of fluid. Same for both sides.

Now get this....If I bled the LSPV, it spewed out insanely fast, never a steady stream. ONLY after bleeding the LSPV, will the rear drums build up fluid and bleed. And again, it bled 2-3 times, and then completely empties out.

I know that we're supposed to bleed the LSPV last, but if I did it last, there was no fluid in the rear drum lines. Even then, there wasn't much fluid.

[Q] Any ideas how why the rears won't bleed. I'm lifted 3", and the LSPV is also left. But I think the bracket only raises it 2" or so. Could the LSPV not be allowing the fluid to run to the rear?

[Q] If I'm lifted 3", should I have lifted the LSPV 3"?

[Q] Should I have continued to bleed the LSPV until there was a steady stream? It seemed never ending.


3) Truck is driving fine. 100x better then before where I had to grind the brake pedal to the floor to get it to stop. Now it start to stop within an inch, and completely stops half way down. Nice and smooth.

[Q] Am I missing something?



Thanks in adavence for any help guys!

 

Make sure your brake system is totally bled, I've always started at furthest brake from the master cylinder and bled each brake from that point. Fill your brake reservoir the the max line, brake fluid is thin it could be sloshing around in the reservoir causing the float to sink momentarily causing brake light in dash to come on. Also check the switch on your e- brake handle to make sure it's tight this could cause brake light to come on also. Hope these help.

 

Im not too sure what u mean by LSPV but our trucks have a height sensing proportioning valve, and unless you relocated it to accomodate the 3" of lift, your brake system thinks there is a lack of weight in the rear, which means it is proportioning all your braking power to the front.
Edit: BAMF makes a relocation bracket i think its like $20. get that and i'd be willing to bet that fixes your problem.

 

So I topped the fluid all the way up to the max line. And drove around the block. The brake light didn't seem to come on. But I'm not a 100% that its gone since it was doing it randomly, 1 out of 5 times. I'll drive it some more and see if its completely gone as the week progresses.

I have the BAMF bracket. I have LSPV (load sensing proportionate valve) set to the full 3.5" of height that BAMF's smaller bracket allowed. But even when I tried to bleed from the rear passenger side first, its like the line ran out of fluid.

So I'm trying to bleed the brakes completely, but I'm not getting much fluid out of the rear after the first couple pumps.

Someone said I should unbolt the LSPV from the axle and raise it up all the way then try to bleed the rears.

I know the All Pro standard leafs are supposed to give 3" of lift but it sure seems to have given me more. So I wonder if I still need to raise the LSPV bar even higher than the the 3.5“ that BAMFs bracket allows to get fluid flowing at the rear?

 

Hmm my bad i didnt realize u had already relocated the PV. But yea thats bizarre i would try like you said lifting the bracket from the all the way up and see if that helps. you should check your metal brake lines too to see if there are any kinks or anything causing an obstruction along the line

 

So after a week, no brake light. I guess the fluid in the Tacos needs to be exactly at the max line to be read full.

But I still can't get the rear brakes to bleed.

I bleed the LSPV/BPV and there was a ton of air in there bleed the front too. The truck brakes 100% better than it did before replying the master cylinder.

I raised the arm all the way up and tried to bleed, and dropped it down and tried to bleed. You name it, they won't bleed.

Could this LSPV /BPV be bad?

 

I've never bled the LSPV last.
I bleed passenger rear, driver rear, LSPV, passenger front, driver front.
I've even used an air actuated pressurized brake flusher and followed that same path. Never had an issue the 5 years I've owned this truck.

And FWIW, if your stock leaf springs were sagging, you probably did see more than 3" of lift but are at 3" over what a stock truck (new springs) would sit at.