Not so, 460 vans had it too.

 

Sounds like a trailer brake controller.
The hissing is coming from a leaking brake booster.

 

I use the truck mainly for snowplowing my property. I put less than a 1000 miles a year on the truck. Not sure if this device is on because I have a myers plow installed or not.

 

If you blew a brake line you need to re-center the proportioning valve's piston.

Check the info in this thread;
https://www.ford-trucks.com/forums/1...ing-valve.html


Your booster's still leaking.

 

My 1985 F150 has the same thing under the dash with the red light...
When I didn't hook that back up on mine when I installed my new master cylinder/break lines/etc.

When you tried to bleed the system did you start with the passenger side rear bleeder screw? Then driver side rear... then passenger side front... then driver side front? I learned that you are supposed start bleeding the system at the farthest point from the master cylinder and work your way to the closest.

 

Ya know, I still don't know how to bleed the damn thing on an F350.... I loosen that nut
some but it starts leaking fluid so I stop, I'm afraid of opening it too far and having springs
or BBs or something fall out (I can see it now..... "Ah, sh3333333tttttt....") and I wouldn't
have the slightest idea how to correctly put it back together, thereby leaving the truck
unmovable until I figure something out.

 

But you DO have the instructions for an F-150.


Hijack complete!

 

Resurrecting this thread. Could someone give me an idea of exactly what makes/models/years to look for to get the parts needed for this? I might be stopping in a junkyard this weekend to look for them. Thanks a lot.

 

So my real question has the group came up with a solid answer to the brakes. I am just getting into my 85 F250 6.9 T19 4x4. I currently am putting 200 miles a day on her. Like a champ 19 mpg at 60. I need a daily and my brake system is replace or upgrade I intend a full rebuild and upgrade to the new freeway travel but biting my time money aside what’s your wish list of full brakes system I don’t have a one to order more then once?

 

If you repair the stock brakes they should work fine.

 

this swap is simple and complex. i have done it and will do it again.
there are various parts that fit various years. the ford pump is weaker and prone w
to whining (wouldnt you)?
the saginaw puts out 1350 psi- for the hydro boost. there is a bracket adapter someone makes to fit a sag. in the ford c2 pump bracket.

There will be a plunger rod alignment issue u will have to address.Tthis means pulling the pedal assy from beneath the dash- good time to add firewall bracket. the hydroboost pedal is $110.00 from ford and the pin is still in the wrong place. ask how i found this out....
the larger bore m.c. from 96 on is the ticket.
something not mentioned in this write up- cooling. the pressure side runs to brakes then to steering, producing lotsa heat. There is a return line from the hydroboost and one from the steering.Tthese need to be connected and run through a cooler of some kind, a filter, and back into the reservoir. Some guys have gone to 3/8 line on return side.
i have auxilary tank too.

the diesel vans have saginaw pumps. get the brackets for sure, they are different from the c2 pump brackets u have.
gas vans have saginaw or mine did.

all of the tahoe, suburban camaro etc have this system too.

purpose: greater pressure. Reports from drum brake users: WOW!

In my case i went from drum to a GM rear axle with disc. it was necessary to have the very largest bore possible; discs require a ton more fluid to move the pistons. my rear axle is a cab chassis model with huge brakes. if you plan to do a rear disc swap, the hydroboost is imperative.

its an invasive surgery on an old truck. but will bring it into the modern era.

it will take a week of trial and error to complete.

c2 pumps will power a hydroboost but here is the dirty secret behind making these pumps work: cool fluid or you cook ur o rings.
pulley installed so there is minimum 1/16-1/8 of the shaft sticking out front of the pulley
saginaw requires a flush pullley and shaft
proper sequence in bleeding the system: with engine off, front of vehicle raised, turn slowly lock to lock 30 times. Do not hard lock to right or left. Topping off. Dont let reservoir empty out on you, these system take a lot more fluid than you would imagine.

last, here is my rant: GM HAS ALL THE BETTER IDEAS, SORRY FORD. ITS JUST THAT KING HENRY THE FIRST, LOVED TRUCKS (FARM BOY) sorry for caps. and built a better truck, read tougher, but the ford components are substandard, especially in the brakes dept.

gm has better engineering and is more clever in solving problems ;hydroboost, hei ignition are 2 examples 14 bolt rear ring and pinion is another AAM axles especially dodges version are supreme.
i look at my frankensteins in the yard and they are made of components sourced from companies other than ford.

looking at it my ford is: cab, frame, steering box (junky ford).
everything else i made, or was sourced from oem suppliers; trans,ZF T CASE: new process 205. axles dana aam.