Upon doing some research, could this be due to that fact that the brakes on these trucks are hydroboost brakes, and aren't vacuum controlled?? That would almost certainly make sense to me.

 

Mine is doing the same thing. Just bought the truck and was curious about the sound and feedback from pedal myself, but never had one before so I thought it was normal.

 

I just bought one also that does it.

 

Ya same situation here.

But I was looking around and heard that these are not vacuum controlled and are hydraulically controlled. So I wonder if it's the hydraulic pump or fluids that make it sound and feel so weird.

 

Just did a search for "power steering flush" there is a link. This may help out. It could be our pumps giving out. Mine has 232k and I don't know if it has ever been replaced.

 

Mine only has 139k miles. I'm going to be pissed if its shot.

Yep, hydroboost. Hows the fluid level?

fluid level is great. I'm thinking its just the nature of the beast. Hoping, anyhow..

I wonder if there is some sort of fluid I can put in there to make it operate more quietly and more efficiently; perhaps some sort of synthetic additive or just totally replace the fluid w/ synthetic..

 

Yep, hydroboost. Hows the fluid level?

 

Check out this interesting read; it's about hydroboost and explains perhaps a lot

Installing A Hydroboost Brake System on a Chevy

 

It could be your power stearing pump, thats what powers your brakes. But it could also be your abs sens. they are on the back of the hub, you can take them out with a small allen wrench and clean them with carb cleaner, and somtimes that does the trick?????

 

I'll give that a try, with the abs sensors. But I'm not quite so sure thats the issue

 

Don't mean to hi-jack, but this would be a good time to remind everyone that there is a direct connection between out power steering and brake booster. If that cheap little power steering resevoir ever leaks down (O-ring between plastic and metal pump) you will have very hard steering and little ability to brake. surely it won't happen on a curvy mountain road! I've read about an upgrade for the PS pump - all metal. Worth looking into I guess?

 

My power steering is down a bit, actually. I dont think it even touches the dipstick. Thats why I'm going to pick up that thicker anit-noise liquid this tuesday and see what happens. I've had good luck in the past with it.

 

The brakes on these trucks do feel a little weird compared to a traditional vacuum boosted system. It's normal for them to sort of push back. I wouln't worry about a little noise on a 10 year old truck with 100k + miles on it. I would however keep the fluid level up and if it's leaking I'd fix that.

 

^Ok good deal. Its not a bad or annoying noise, just a noise that made me think "wtf?". But I'm almost certain its just because it's a hydroboost setup and not vac setup.
I'm going to top the fluid off w/ that special anti-noise stuff and will post the results back here.

 

Having the Same Problem For the Third Time...

From what is being described... I have the same problem. Actually, I have had this problem twice already... For both of the previous time this happened I took the truck into the dealer... here is a short description of what they "fixed"...

Hydro-Boost Assymblely (both times it was in)
Hi-Pressure Hose (it was "restricted")

This frist time it was in the Hydro-Boost was "zeeping" at the rear seal... and the second time it was "zeeping" at the center seal.

Maybe, this will help in diagnosing your problem further... right now I have to decide if I want to take it in and have it fixed a third time... or try and do the repair myself...

Ben

 

Interesting. I had finally come to the conclusion that it was just the nature of the beast of a hydro boost setup, but now I'm curious..

 

The hose that threads into the power steering pump and then up to the brake booster blew on my truck last week...in the middle of me moving to a new house, no brakes and no power steering. Thats the same exact noise it made. If your power steering gets very low, it WILL affect your brakes.

 

Thanks for the input. I know it was a bit low a few weeks ago. I'm gonna check it tomorrow. I'm going to put the stop-leak stuff in it, I've had good luck with it. I'll report back how it works as far as noise and pedal feel/noise

 

If your truck makes that whining noise when you press the brakes or turn the wheel, you probably need to skip the flushing part, and go directly to a new PS pump. They are cheap (~$45), and the peace of mind is worth it in my opinion.

Furthermore, if your brakes are acting up, that is, pushing back on your foot, then you probably have already done damage to your brake booster. A stiff feel isn't really a problem, so long as the booster is still doing it's job. If it is actually pushing your foot back, you have a major problem. It means that the internals of the booster are shot and it needs to be replaced ASAP. It will get to the point that you will simply *not* be able to push on the petal hard enough to apply the brakes. It is not just 'not working', it is actually actively preventing you from applying the brakes. The hydraulic pressure that should be boosting your petal is actually pushing it up instead of down.

 

Well here's how it works from my best explanation. Say I apply the brakes gently. They feel like normal big-truck brakes. Say I'm in neutral messing around testing them. If I kick the brake relatively hard, so that it goes in 1/4 the way or more, the pedal almost "absorbs" my foot, then makes a weird noise and starts resisting and pushing my foot back. I'm used to using either vac. brakes or air brakes, never used this hydrboost system (not enough to pay attention to this anyhow), so I'm really just thinking it's the way the system is setup, and I just have to get accustomed to it. Thanks a lot for the input though.. keep it coming!

Eli obviously has allot of experience with these trucks so I would certainly take is advice under consideration but I disagree with him slightly on a couple of things.

Even when new and in perfect condition the brakes on these feel different and will sometimes feel like their pushing back slightly. I think that it's more that it takes a noticeable fraction of a second before the boost catches up than actually pushing back. If it's really pushing back then yes you do have a problem and you certainly don't want to mess around waiting for it to fail completely.

If I ran an ambulance fleet like Eli I probably would replace the PS pump when it made noise but otherwise I really wouldn't get that worked up about a Ford PS pump with a bunch of mileage on it that makes some noise when it's working. I think I've heard more noisy ones than quiet ones.

You do need to make sure that there's fluid in it and fix any leaks so that it stays full.

Based on some of 85 305's other posts he's a driver that's very sensitive to his vehicle (a good thing as far as I'm concerned) and is likely to notice things like the different brake pedal feel that allot of other drivers would never pick up on. I don't want to be casual about brake issues but I really suspect that aside from a low fluid issue there's nothing wrong with the boost system on his truck.

I think you are right in what you are describing, how it feels like it pushes back slightly. I think I just need to get used to this different type of braking system.

Thanks for the compliment though! Lol. I've owned a LOT of cars (plan on keeping this one), so I pretty much pay attention to every little thing and keep mental notes of changes. I'm pretty "spiritual" about cars, if you will, and always try staying on top of things. I checked the fluid a few weeks ago, and I keep forgetting to check it again. But I'm going to buy some noise stopping stuff in a few mins and see how it works.

 

ok just found this thread. for the first post, that wining is the pwr steering pump. and thats what powers our brakes. vac is powering the obs trucks

 

Eli obviously has allot of experience with these trucks so I would certainly take is advice under consideration but I disagree with him slightly on a couple of things.

Even when new and in perfect condition the brakes on these feel different and will sometimes feel like their pushing back slightly. I think that it's more that it takes a noticeable fraction of a second before the boost catches up than actually pushing back. If it's really pushing back then yes you do have a problem and you certainly don't want to mess around waiting for it to fail completely.

If I ran an ambulance fleet like Eli I probably would replace the PS pump when it made noise but otherwise I really wouldn't get that worked up about a Ford PS pump with a bunch of mileage on it that makes some noise when it's working. I think I've heard more noisy ones than quiet ones.

You do need to make sure that there's fluid in it and fix any leaks so that it stays full.

Based on some of 85 305's other posts he's a driver that's very sensitive to his vehicle (a good thing as far as I'm concerned) and is likely to notice things like the different brake pedal feel that allot of other drivers would never pick up on. I don't want to be casual about brake issues but I really suspect that aside from a low fluid issue there's nothing wrong with the boost system on his truck.

 

Noise Only in drive and reverse

I have a whining noise that only happens in drive gears in my 2000 Excursion. Does the power steering/ hydroboost whining noise you have all experienced happen in all transmission positions? My ps fluid level is good and my noise doesnt change if the truck is turning. any insight?