Hi there.

My '06 FEH failed VA safety inspection for a few things. Got those all fixed, but while I was replacing the lower control arms (one had a bad bushing and one had a ripped ball joint boot), I noticed the front brake hoses look like this:



So I think it's time to replace them on all 4 corners. Now, normally this would be a job I wouldn't think twice about, but I'm mildly terrified of doing this job because of the finnicky nature of the HCU. I bought a motive power pressure bleeder with the idea of changing the brake fluid before I discovered the condition of these hoses (I've read a few accounts online of people using pressure bleeders to change the fluid in these early FEHs with the HCU). Basically, I'm terrified of getting air back up into the HCU during the hose change-out, mainly because the bleed procedure in FORscan appears to be glitched, and I don't want to deal with taking it to a Ford dealer who will, in all likelihood, have no idea how to bleed this system given the age of these FEHs now.

So I've thought through this and this is what I'm thinking for the hose change-out procedure (per corner) to avoid any air getting to the HCU:

1. Disconnect 12V battery.
2. Attach pressure bleeder to the master cylinder, fill with fluid, and pressurize to ~35psi.
3. Crack the bleeder screw on the caliper to ensure the pressure bleeder is forcing fluid through, close caliper bleeder.
   • Question here: Is there a way to relieve the pressure stored in the HCU accumulator? Maybe disconnect the battery and let it sit for a few days? I don't want HCU accumulator pressure tricking me into thinking the pressure bleeder is doing its job.
4. With the pressure bleeder still attached and pressurized, quickly swap out the hose.
5. Crack caliper bleeder to bleed air out of the new hose.

Am I missing anything here? The idea with the pressure bleeder is to keep fluid moving through the system for the entire process so air doesn't have the opportunity to migrate up into the HCU while swapping the hose out. I am certainly open to any other feedback/suggestions/etc. Part of me also thinks I'm overthinking this; the hard brake line does a vertical hard 90 up to the hose, so theoretically air wouldn't travel DOWN the line and then back up into the HCU.

I'm planning on taking this on this coming weekend, so I will report back with success/failure/advice for the internet record.

Thanks!

 

good luck with this. I will eventually face this replacement on my son's 08. I have over the years seen posts where run of the mill tire shops have replaced these hoses due to internal collapse failures. I doubt seriously the shops did anything out of the ordinary besides disconnecting the 12 volt battery ground.

 

Thanks. I'll let you know how it goes. Want to get it out there on the internet so it may help somebody else in the future too. I'm planning on changing them out tonight/tomorrow. Had the car safety inspected, fixed everything they said was wrong, took it back to get it through safety before changing the brake hoses, and then they failed me for the brake hoses. Very confidence inspiring in a shop when they miss something as simple as brake hoses (and then they tried to blame me by saying they probably cracked during the work I did).

Anyway, rant over, I'll post back and let everybody know how it goes.

 

Reporting back. Got the hoses replaced yesterday and everything went well.

First step was to disconnect the battery and fuses 31 and 24 for the HCU.

I used the Motive Product 0107 Pressure Bleeder to keep ~15 psi on the braking system while swapping the hoses out. A steady stream of brake fluid was coming out of the hard line while swapping. I changed the hoses out quickly and then opened the bleeder on the caliper and all the bubbles came out. I kept the system pressurized for a while and ran probably between a half quart and a quart of fluid through each side on the front to flush (note: the pressure bleeder will require a little bit of pumping during this to maintain pressure). I also did the same for the rears and flushed them using the same procedure (just pressurized the system and cracked a bleeder and let it drain for a while). Overall went well. I'm hoping that some of the new fluid made it into the accumulator of the HCU; it was acting up last year in the heat (open to feedback on if you think I actually did get fluid out of the accumulator).

When I started the car up I initially got a "service brake system" message pop up and the brakes were in failsafe mode. I restarted the car and let the HCU cycle a few times, and all has been fine since (I'm assuming this was a result of having the power disconnected from the brakes). I then took the car to a gravel road and did a bunch of emergency stops to activate the ABS and make sure everything was working. Overall a simple job; don't let the HCU intimidate you. As long as you maintain positive pressure on the brake system from the MC reservoir it's an easy job.

I have noticed a few other forum posts I've found had people putting 35 psi on the braking system to flush it; I didn't have to do that. Not sure why they needed so much.

 

good work; thanks for doucmenting here.

 

Just did both the front brake hoses on my '09 MMH, the hoses looked OK, no cracks but there must have been a restriction that kept the caliper pistons from quickly releasing pressure as people have noted.
I didn't do anything special, bled the system like any other and what an improvement, no more grabbing, or creaking noises after a stop,
got two "Sunsong" hoses from Home Depot delivered for $19.29 they fit perfect, there might be better hoses, but they're better than what was on there
Local shop wanted $290