Hi guys! I haven't been on in awhile, as I haven't had any real troubles. I have been reading all of these threads, as everybody seems to have brake problems on these IDI's. I have a hissing sound when the pedal is depressed, and only good brakes when I pump the pedal. All new hardware on the rear end, calipers and pads are good up front. Vacuum pump is only a few years old, while brake booster has never been changed. This must be the booster right? Brakes are bled, and no leaks are present. I haven't had the time to do any diagnosis, but will get to it asap. I have heard that you should replace master cylinder with brake booster, but I'm wondering if it is necessary?? Also, if anyone has any tips or tricks to replacing a booster they will be very appreciated!!

Thanks guys!!
1990 F250 7.3 IDI ZF5 N/A SC LB

 

When I had the hissing noise you described, it was indeed the brake booster. I didn't replace the master along with it, because the master was fairly new already. The job was fairly simple and straightforward.

 

Thanks 86-IDI! My master has never been replaced, but I haven't had any troubles with it. Should it be replaced? Also, is there any o-rings or any other parts that should be replaced along with the booster?

 

If your master hasn't been replaced, it might be a good idea. I think they sell both the master cylinder and booster together if you want to replace both.

 

I have ordered a M/C attached to the brake booster, and it should be in today or tomorrow. It doesn't come with a reservoir, but there shouldn't be any problems if I reuse my old reservoir eh? Should I replace anything on the reservoir when I put it on the new M/C?

 

The instructions that came with the new M/C booster combo states that it has to be level when bleeding it in the vehicle. The way it sits in the truck, it isn't perfectly level. As long as I keep the reservoir full when bleeding, wouldn't that work? I'll get a helper to watch the fluid level, and add more if it gets low, while I push on the pedal.

 

You should bench bleed it first, before installing. Otherwise you might get air trapped in the master. That is probably why they say it has to be level...
You could park on a hill (well gentle hill..) as one way to make it level in the vehicle. Or jack up whichever end you need to.

 

i would mount the master/booster in the truck, and get a set of adapter hoses that screw into the master cylinder outlet ports. connect a small hose to the adapters and put the other end into the master cylinder fluid reservoir. have your helper slowly pump the brakes until you no longer see any bubbles coming out of the hoses.
then you are ready to hook the steel lines up to the master cylinder and bleed the complete system.

 

Usually a new m/c comes with those ^^^^^ adapters with little hoses, for bench or in-cab bleeding.

 

ok wasn't sure if they still did or not. it has been a while since i installed a master, and i know how cheap the manufacturers have gotten. if they can safe 3 cents by not adding them they will.

 

I got the Booster M/C combo from Cardone Industries. The hoses and fittings you guys mentioned above aren't included, as Cardone has a new bleeding process. Instead of getting the hoses and fittings like I thought I would, I got two little plastic thread-in plugs; a blue one and a yellow one. Apparently this is supposed to be a better process than before. tjc, you are right about them saving 3 cents lol! But if it is a better bleeding process, then I guess its a win-win all around

Here is the link, hope it works: https://www.cardone.com/tech-help/br...ding-procedure