I always thought the brakes on my Excursion weren’t exactly confidence inspiring. I have a V10 with vacuum assist brakes. I have replaced most hard lines and have also installed the Russell stainless braided lines front and rear. I bought a 2004 diesel F350 a while ago to steal the ZF-6, so I figured I would neuter the hydroboost unit and pedal to give it a shot on my truck.

Attachment 278532

The hydroboost was offered as factory from Ford with the V10 on the larger trucks (F650), so the hoses are available for purchase. You will need Gates 352790 (hydroboost to gear) and 365431 (pump to hydroboost) pressure lines. I also bought Gates 352897 return hose to hack up and tie into my existing lines.



First is to clean off the hydroboost unit and pretty it up with some spray paint.





Looks like my existing pump to gear pressure hose is leaking (I believe this is a common failure point).



Then you need to remove the vacuum booster from the truck. Remove the master cylinder and hang it out of the way without messing up your brake lines. Remove the vacuum line to the booster. Then, go in the truck and remove your existing brake pedal (no pics of that). Curse as you have troubles because it keeps getting hung up on the insulation on the firewall.









I took some comparison pics of the pedals. Notice the different booster attachment point, which alters the travel/leverage.







Then, bolt up the pedal and hydroboost to the truck.





I took the power steering pump off for easier access to the hose fitting. You can see the existing short hose that goes directly to the gear and the new hose that goes up to your new hydroboost.



I tee’d in the return line to the smaller of the two return hoses that attach to the bottom of the power steering reservoir. I used a brass tee fitting.



Bleed the system fully. It takes a long time. I followed these instructions: . It took me a long time. I put my laptop on the console and watched some videos to keep myself entertained during that process.

Bonus pic of the axle that’s waiting on parts from PMF.



The brakes feel much better to me. There is a chance my vacuum booster was bad, but who knows. I am satisfied with the change. I do notice a slight hum with the new parts. In my research for this project, I saw someone else also had the same problem. I do not believe I have any air in the system. If anyone has any ideas, I’m listening.

I am planning on a flush with some new ATF, because I accidentally added PS fluid the first time I bolted everything back together. I did drain that and put some ATF in before I completed my bleed and started the truck, but I’m sure it is contaminated a bit. Oh and don't forget to plug the vacuum line you removed from the old vacuum booster.

 

Great write up! This should go in the tech folder.

 

One thing I forgot to mention, there was a foam gasket on the vacuum booster on the area around the perimeter of where it interfaced with the firewall. It disintegrated during disassembly. I believe the hydroboost is supposed to have some type of gasket as well. I put some foam tape that I had around that area before I bolted it to the firewall.

 

Now, what to do with all that "Extra" vacuum....?

 

Now, what to do with all that "Extra" vacuum....?/QUOTE]
You could always install a Wolf Whistle.
(I think only the OG ‘s know what that is)

 

Thanks for the great write up RPhil. I've been accumulating the parts for a few weeks and finally started the switch. DIdn't realize when I bought the used HydroBoost unit that the pedal was an power adjustable unit. Luckily he included all of the pieces for it. I was able to figure out how to adjust the pedal using just the cable attached and my cordless drill.
Once I got all of the pieces, I started the swap. Went along pretty well. I was able to remove the old hose off of the bottom of the PS pump while it was still on the truck. I had some old offset short open ended wrenches that fit in there good.
I ran into an issue with the used HydroBoost because when it was removed from old truck, they twisted off the steel pipe that attached from HydroBoost to hoses. I went to OReilly to see if they had these short right angle tubes. Special order from Gates and one was $300 and the other was $250. Whoa! Started investigating on internet and found one on PartsHawk for $50 and the other (different size fitting on HydroBoost - go figure ) from eBay for $30. Once I got those installed. I did the a complete purge of fluid using this process.
I thought I'd still better bleed the system to be absolutely sure I got all of the air out. Everything worked out good and I wish I would've done this years ago. MUCH more confidence when applying the brakes. I can't wait to see what happens when I pull my enclosed trailer with my SxS and 4 wheeler. There is more of a whine from the system under the hood but I will take that for these brakes!
At the same time I instead a new Bilstean steering stabilizer. I think that and using new Mercon V fluid in system improved the steering too. I think I used different PS fluid in the past (non Mercon). THat's one reason I wanted to purge the system. Well worth it.
Thanks again. Next upgrade is to regear the differentials to 4:56. I've never done that and trying to build up the courage....
zeppelindad

 

I'm happy you found it helpful.

The underhood whine is still there for me. It is very noticeable and pretty annoying to be honest. I just deal with it, I would rather have improved brakes with a whine than my old brakes and no whine!

 

Why not use Power Steering fluid? That's what they fill them with from the factory. There are a few full synthetic power steering fluids out there (I like Redline personally) that have been working in all my hydroboost trucks for years now. Is there something inherently better about ATF?
...

 

ATF is what is specified per Ford.

 

Well, I'll be darn. I grabbed the service manual for the Excursion off the shelf and sure enough it calls for ATF.

Ford now sells at power steering fluid (called XL-14) but it would appear that its only repackaged Mercon V ATF ( its even still red in color according to the SDS ).

Most hydroboost units are made by Bosch (or at least they used to be, Hydroboost was actually a registered trademark of Robert Bosch Corp but that may have expired or been sold by now). My Dodge and GM hydroboost vehicles call for their respective companies brand of power steering fluid, so it would seems the hydroboost unit doesn't care and the same goes for Borgeson power steering boxes that most manufactures use (not sure if the XR50 box the Excursion has is a Borgeson piece or not though).

I'm guessing that Ford just reached into their parts bin for a fluid that'd work. I wouldn't be to concerned about having power steering fluid in there, but you are correct that Ford calls for ATF in their power steering system.
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