How to tell If hydro boost is working?

[THEFERMANATOR]

If the pedal is going all the way down, check to see if your losing fluid. If you are you have a leak, if your not the master cylinder is shot.

 

[WarWagon]

Last OEM items left in the brake system is the hydroboost, Master cylinder, and ABS unit?

Would bleeding the ABS system matter? Esp with a MC replacement? Maybe a vacuum bleeder...

Out of the blue I would disconnect power to the ABS. It's possible it's going off on you. I have fond memories of hitting paint strips and stopping in, rather than before, the intersection on a 1992 Olds Bravada - my God what a POS that was and the antilock I literally bent the brake pedal trying to stop the damn thing once fighting the ABS and worthless Uniroyal tires.

Here is the sensor you are looking for IF there is on on the back of the PS pump. It would be hard to see for sure. Looks like people replace complete pump with one from a 1996/1995. (New or junkyard at that vs. trash rebuilt.) Diesels may have different pressure springs in the pump vs. gas engines w/o hydroboost.

 

[Will L.]

I saved some manuals over the years, but wow, a kit instruction sheet! Your kinda scaring me pulling that out.

 

[Big T]

Alright, I reached down there on the pump and there's no EVO, just the tube coming out. Took a photo using the iPhone, but can't load it here. Can't even find old photo albums with this new forum software.

 

[WarWagon]

I saved some manuals over the years, but wow, a kit instruction sheet! Your kinda scaring me pulling that out.

I got more of those than I like with all the PS pump swaps I did on the 1995.

One less thing to chase down for Big T.

 

[Big T]

No leaks in the system. So looks like I'll be doing the master cylinder. Any special tricks I need to be aware of?

 

[THEFERMANATOR]

Bench bleed it REALLY GOOD!, do NOT turn the key on until you are CERTAIN all the air is out of the system, and don't use alot of pedal pressure when bleeding the brakes or else you can push air into the ABS system and then need a scan tool to trigger the ABS to do a bleed of it's system. The best way to bleed the brakes to avoid getting air into the ABS when replacing a master cylinder is to reverse bleed. Also make sure and run alot of fluid through the system to get all the old moisture contaminated fluid out.

 

[Big T]

Bench bleed it REALLY GOOD!, do NOT turn the key on until you are CERTAIN all the air is out of the system, and don't use alot of pedal pressure when bleeding the brakes or else you can push air into the ABS system and then need a scan tool to trigger the ABS to do a bleed of it's system. The best way to bleed the brakes to avoid getting air into the ABS when replacing a master cylinder is to reverse bleed. Also make sure and run alot of fluid through the system to get all the old moisture contaminated fluid out.

Hate to admit it, but have never done the bench bleed thing and could benefit with a description.

 

[WarWagon]

 

[Big T]

Thanks WarWagon. Pretty much what I envisioned. I'll have to get the fittings and tubing. My vice is up at Big Bear so I'll being doing it up there this weekend.