Thanks for the welcome CampSpringsJohn.

 

What are you using for fluid?

 

I lost my manners there but after seeing John's post I looked and seen you were new around FTE.
It is always nice to see a new face "Welcome "
Now there is a nice write up on post #7 by Thomas White that can be helpful.
https://www.ford-trucks.com/forums/1...boost-bad.html

Now I don't know in what order you were going to do what but I would start with flushing the P/S first and I use a good AFT. I use Mercon V in mine. There is a very good write about how to do a p/s flush but I couldn't find it. If I recall correctly you remove the return hose off the hydo which is on the top of hydo. Put a clear hose on it run it into a bucket and run about 3 or 4 quarts thru it. It might have been more then 4 qts. It has been a few years since I did mine.

 

When I do mine, I jack the front up off the ground.

Suck as much old fluid out of the pump as I can.

Pull the return line off the Hydroboost and put a rubber line on the hydroboost and run it to a clear 1 gallon jug. Usually an empty windshield washer jug.

Then start the truck and turn the wheels from lock to lock a couple times, and stop at straight ahead. Then I hit my brake pedal about 3 or 4 times, top off the Power steering Pump, and repeat. I do this until I see good clean fluid coming out of the hose. Usually requires 3 to 4 quarts. When I see good fluid, I re-install the return line, make sure the PS pump is full, and take the jack stands out from under it. Be sure to check the level again after a day or 2 of driving.

Edit: Keep in mind, the PS pump does not hold a lot of fluid. It takes quite a few times to do this completely. You don't want to run the pump too low.

I have never noticed much difference in the steering or braking after doing this. But I certainly do feel better just knowing the PS has good clean fluid. Every truck I've done this to had fluid that was black! Since then, I make it a point to suck as much PS/trany fluid out of the pump once a year and top off with new fluid just to keep it clean.

 

So I said I would share results. Yesterday I flushed the PS fluid. It was not dirty at all. I also pulled the master cylinder for replacement. While the MC was off I tried to remedy the slow brake pedal return previously mentioned. I lubed the inside push rod portion of the hydro boost. I sprayed the moving parts with a dry spray lube, as well as the accessible portion inside the cab at the firewall. This seemed to free it up and it began returning quickly (normal) with the master cylinder off. I bench bled the MC. And bled it again on the truck. Then bled all four corners in proper order manually. Got a bunch of air and the pedal seemed good and returned quickly. Then drove away.
Same damn problems. Fading to floor pedal before stopping and painfully slow pedal return. Second pump of pedal gives good brakes and stopping but return is so slow that pumping twice to stop is not a realistic option a lot of the time. I cannot continue to throw money at the problem.
Anyone who has solved this please help me out here!

 

There is a procedure to bleed the brakes at the ABS module, but I've never done that. At this point, I don't know what else it could be, unless it's a stuck brake caliper or 2. I had that issue a few years ago where it took a lot of pedal to stop, not to the floor. Found one of the brake calipers had a frozen slide pin. The caliper was wearing crooked, and it took a lot of brake fluid to push it out to work.

 

Thanks CampSpringsJohn. There are no stuck calipers and I have bled the abs with a scanner twice with no improvement. I am beginning to think maybe the cause of the painfully slow pedal return is the root of the problem here. I just can't think of what I could lube the inside of the mechanism with. The dry lube spray worked very temporarily. Lithium lube always gets gummy after a while. I need to figure out a non volatile lubricant that won't get gummy over time, or too heavy in the cold and see what that does.

 

Bleeding ABS sounds like its worth investigating,if you want to test for caliper problems,You can pinch all caliper hoses off & release one at a time to find the problem caliper,but this test is questioned by some of being tough on the hoses even though its practiced in a lot of brake/alighnment shops.

 

Ok. New master cylinder. PS pump has been replaced. Hydro boost unit appears to me to have been replaced. I am beginning to think the previous owner had been chasing this problem as well.
I am leaning more and more back toward my original plan of converting to vacuum boost. I believe if I obtain a vacuum pump from a 2006-2009 saab 2.8 turbo as well as the vacuum switch/activation relay, and the vacuum booster from a gas excursion I should have what I need.
I had a super heavy duty extended cab dually for years with vacuum boost and was perfectly happy with the braking so I will take the simplicity of the vacuum system in a heartbeat.
I welcome any input, but I have tried and/or checked all avenues I have seen suggested thus far to make the hydro boost work.

 

I am not a hydroboost expert, but have worked on a number of brakes. So I'll throw in my $.02, just in case.

1. Air in brake lines. Bleed them, run fluid through for a good 10 mins. Sometimes air gets in the middle of the line and has to be pushed through.

2. Leaking brake line. Yep, most of the time, see them on/around the rear axle. Sometimes hard to see. Get a buddy to stomp on the pedal while you look with a flashlight on a hard surface. A couple of pumps should give you signs

3. Sticking or leaking calipers. When the seals in the pistons go and let fluid bypass, but it isn't completely gone, the pistons won't return properly. Also rusty caliper pistons.

4. Hung up brakes. Thought we had a major failure in a motorhome. Turned out a piece of gravel got in and jammed the brakes.

5. Here's an unusual one. Brake calipers reversed/upside down on fronts. Bleeder was on the bottom. Left was on right side and vice-versa. Couldn't get the guy to listen to me. He replaced MC, cut the lines to the ABS module and bypassed it (expensive), just about anything and everything except the calipers. "They were like that from the factory," he said. Mazda ("Ford Ranger"). Couldn't get the air out and brakes were spongy and took that second press but not right.

6. Bad rubber lines can fail internally. I haven't had this personally, thought it was old wives tale, but the explanation sounds plausible, I guess?

7. I haven't seen where you've confirmed you are using synthetic ATF (what kind?) instead of Power steering fluid. Not usually a big deal, but since you are still having issues, gotta check everything

Hope this helps.

 

Years ago a buddy of mine had a problem with his brakes having air in them. Could not figure it out. Changed master cylinder, still had it. Turned out to be the sensor on the master cylinder that turned off the cruise control was leaking, one way. No fluid would come out, but every time you let up on the brake pedal, air would be sucked in.

 

CampSpringsJohn that is an interesting thought I had not considered. That is easily checked out. I'll take a look there.
ExPACamper I have eliminated everything on that list but the synthetic fluid. But as a mechanic with 28 years experience I can pretty confidently say changing to synthetic is not going to make a difference in performance. Longevity maybe.

 

True, as long as it's Mercon V rated, should be fine.

You obviously know, but some might not realize that it doesn't take "Power Steering" fluid

Hope you find it soon.

 

Thanks ExPACamper. Me too, and yes I flushed with fresh Merc V. Got a couple other things to look at before I pull the trigger on the conversion. I will keep everyone informed of my progress.