So this is a carry over post since the other one I made is too spotty with what I have done to my trucks brake system. So I am going to condense it to this post.

This is everything I have done to my trucks brake system:

• Replaced rear shoes and all hardware, replaced the wheel cylinders, bled the system and set rear shoes correctly .
• Replaced all rubber lines since the old ones were probably 31 years old and bled the system again.
• Replaced front brake calipers and bled the system again.(rear l, rear r, front r, front left)
• Replaced the Master Cylinder (bled on bench and on truck) and replaced the brake booster and again I bled all the brakes.
• Took the spring out of the RABS module to bleed it and then put the spring back in after bleeding. However I noticed while the cap was off the module, brake fluid was leaking out from where the spring sits.
• I replaced parts because they were worn and or original parts.

I am out of things to either check or replace as I still have a sinking pedal. I have bled them with 2 people, gravity and vacuum but I seem to have air with every bleed. The brake pedal feels decent with the truck off but sinks once stated up and then slowly returns.

Is my RABS module bad, or is something else going on? I have gone over the brake system with a fine tooth comb at this point and haven't seen any leaks that could be introducing air. The truck is a Georgia truck and has hardly any rust on it and the rust it does have is surface only. Should I bypass the RABS module, and if so with what part(s)?

 

the Kelsey hayes RABS valves don’t often fail let alone cause hydraulic gremlins.

I noticed new shoes , show us. Show us your shoes and hardware. I made a silly mistake ajd it make them work a lot different than it was supposed to.

also, you said you replaced booster and master cylinder..? We’re they bad? They are not needed to be replaced unless they fail… the new ones could easily be JUNK the mc primarily.

did you adjust the length of the pushrod into the mc

and how is your pushrod on pedal doing? Pedal pivots?

replace your Mc cap lately?

 

If you hear any whooshing when applying the pedal it COULD be the booster. If yours is original like your other components the diaphragm is probably ruptured. If no whooshing your symptoms are probably a bad master cylinder. You did it properly by bench bleeding but new parts fail regularly these days. Or check you rear inside of hubs and make sure your wheel cylinders are not leaking which is another possible bad part from the seller. Again that is not uncommon these days.

 

Before I decided to tackle this brake issue my RABS light was on all the time, every time I would drive it. I replaced the little sensor that sits on the differential thinking that was part of the problem, part was cheap enough but it did not make the light go out.

So for now I cannot get pictures of the rear drums, shoes and all since I only have two jack stands which are on the front since the front wheels are off.

I replaced the MC and booster as a pair since I read that was recommended. The old which was a Motorcraft MC sprung a leak on the rubber gasket that connects the plastic reservoir to the actual MC. The booster had rust and corrosion running down it plus had some crud sitting where the rod that pushes in the MC piston sits.

I adjusted the rod that pushes on the MC to the point of having very little play I had to take my time with this since the new parts had a fair bit of play in them.

Not sure what you mean by pedal pivots, if you mean did I install that circular part(that comes from the booster) back on the actual brake pedal and put the plastic bushing back on then yes.

The MC reservoir cap is a new unit since it came with the new Ford Motorcraft MC doesn't appear to have any damage.

As of now I am not seeing any leaks but the pedal still fades a substantial amount with the truck running. I just started it up a few minutes ago and noticed after I shut the truck off I hear a very faint hissing noise coming from the MC/ Booster area. If I depress the pedal the I can hear the woosh sound and the slight hissing stops.

 

As far as I know the wheel cylinders are good. I replaced them towards the beginning of me owning the truck. I'll see if I can get at them with the limited equipment I got. Only got two jack stands and a jack at the moment.

 

No reason to jack it up unless you can't get under the truck. A visual look should suffice for leaking fluid. You can pump the pedal with key on a few times before looking.

 

I forgot to mention, the brake fluid level has not gone down at all. I filled it last night after bleeding the RABS module and looked this morning and no change. Even after I pressed the pedal a few dozen times no change in the level.

 

If the level didn't change and it is a PIA then move to the whoosing. If no issue then my only suggestion is to return the MC and try a new one. I know it's not fun but I don't know where to go from there.

 

Sorry if I sound dumb, not sure what you mean by PIA?

 

PIA Pain in the *** for checking the cylinders since the level didn't change.

 

Gotcha, lol

 

did you by chance use the tool to adjust the pushrod length to the mc. It’s sometimes a very finicky touchy adjustment for some people but I haven’t done anything personally like that so I don’t know.





Can you snap a few pics like these on my truck but on yours? Mine should not be used as a should-be because I don’t think mine is right /an extension cord kinda in the way there but I was just demonstrating where you should take pics

 

Also even tho you got a motor craft part , just know that it doesn’t mean quality like the OE would have been. The original brake system was produced to my knowledge by bendix and the ABS functions by Kelsey Hayes and then just slapped together on a vehicle by Ford. The bendix OE part is probably not the same as the replacement because to my knowledge bendix stopped making them at least in this gen case, few years ago. So unless it’s rebuilt it’s hard to say who physically produced it unless a manufacturer logo or casting can be seen

 

[QUOTE=AuroraGirl;19991830]did you by chance use the tool to adjust the pushrod length to the mc. It’s sometimes a very finicky touchy adjustment for some people but I haven’t done anything personally like that so I don’t know.

Here is a link for him to follow your good suggestion. I searched for a 93 but the 90 should be the same.
https://www.google.com/search?q=How+to+adjust+the+brake+booster+push+rod+ on+a+1993+ford+f150&sxsrf=ALeKk03PdKE4jIJRXFnG24hb 72AcACxUww%3A1627501743037&source=hp&ei=rrQBYZClPM Lj-gTI4rXYAw&iflsig=AINFCbYAAAAAYQHCvwKZWZ0ogpfaT84wP lapPIGnb1-8&oq=How+to+adjust+the+brake+booster+push+rod+on+a +1993+ford+f150&gs_lcp=Cgdnd3Mtd2l6EAMyBQghEKsCMgU IIRCrAjoHCCMQ6gIQJzoECCMQJzoFCAAQkQI6CwguEIAEELEDE IMBOg4ILhCABBCxAxDHARCjAjoFCAAQgAQ6CwgAEIAEELEDEIM BOg0ILhCxAxDHARCjAhBDOggIABCABBCxAzoHCAAQsQMQQzoIC AAQsQMQgwE6CAgAEIAEEMkDOgUIABCSAzoGCAAQFhAeOgUIABC GAzoFCCEQoAE6BQgAEM0CUKImWKq4AmD4vAJoAnAAeACAAaMBi AGvLpIBBTM1LjI1mAEAoAEBqgEHZ3dzLXdperABCg&sclient= gws-wiz&ved=0ahUKEwiQtIy6xIbyAhXCsZ4KHUhxDTsQ4dUDCAo&u act=5
Videos on how and below some and some forum info to read.

 

The MC that came off that was leaking says Tokiko on it, a Japanese part from what I have seen. The new one I got says the same thing, the markings on the new and old are: Tokiko on one side and 1-1/16 on the other side, part of the reason I got a new Ford MC was it being made in Japan. The booster I got was a rebuilt part, company was Cardone.

I got some pictures here:
Something I should add too: when the truck is off the pedal springs back quickly and seems firm, but when the truck is running the pedal sinks and firms up towards the end, but not hitting the floor, and it takes a second or two for the pedal to go back up.