Noise when turning wheel while foot is on brake

[LuckyTaxi]

Let's say I'm pulling out of a parking spot and I have my foot the the brake pedal while I'm turning my steering wheel. I hear this loud shrieking noise as I'm turning the wheel. Only happens when my foot is on the brake. what the heck is it and should i be concern?

 

[Zenmervolt]

The power steering and the brakes are not connected in any way. Put the car in "Park" and turn the steering wheel, you will probably hear the same sounds.

It is much more difficult to turn the wheels when the car is not moving, which means that the power steering pump has to work harder when the car is sitting still. Most cars will groan a little bit when they're sitting still and someone turns the wheel. It's also possible that the power steering belt is getting old and is slipping when there's more load on the pump. I would first check the tension on the PS belt, and if that's OK, I'd try replacing the belt. After that, if there are no other problems I'd probably leave it, but if it really worries you, go and have a mechanic inspect it and tell you if the noise is OK.

ZV

 

[exdeath]

Originally posted by: Zenmervolt
The power steering and the brakes are not connected in any way. Put the car in "Park" and turn the steering wheel, you will probably hear the same sounds.

ZV

Hydroboost brakes like the system Ford has, uses the power steering pump to provide the power assist to the brakes instead of a vacuum booster. Maybe low power steering fluid could cause the traditional steering squeal/whine when the brakes are applied at the same time and there isn't enough volume in the hydraulic system to cope with both at the same time?

 

[LuckyTaxi]

ah ok ... makes sense ... other than that the car seems fine. thanks!

 

[jagec]

Originally posted by: exdeath

Originally posted by: Zenmervolt
The power steering and the brakes are not connected in any way. Put the car in "Park" and turn the steering wheel, you will probably hear the same sounds.

ZV

Hydroboost brakes like the system Ford has, uses the power steering pump to provide the power assist to the brakes instead of a vacuum booster. Maybe low power steering fluid could cause the traditional steering squeal/whine when the brakes are applied at the same time and there isn't enough volume in the hydraulic system to cope with both at the same time?

You're kidding, right? Seems much more likely that someone would develop a leak in their power steering system (or just not fill it up), and lose their power brakes, than a break in the vacuum line.

Sounds like poor engineering to me. The vacuum boost has worked great since time immemorial, and been consistantly reliable. Same reason I'd be suspicious of a company that went to electric brakes...no reason to change a working system that's reliable and has few downsides.

 

[LTC8K6]

As far as I know, Ford rarely used the hydraulic brake booster, one example being on Lincoln Mark 7's, I believe. Most Fords will be your standard vacuum boost system.

 

[LTC8K6]

Could it be your brake pad wear indicator?

 

[exdeath]

No I'm not kidding...

http://cgi.ebay.com/ebaymotors...ameZWD1VQQcmdZViewItem

It was just a logical hypothesis that since there is a problem ONLY when both turning and braking at the same time that the two may be related in some way... hence hydroboost brakes competing with the power steering system or something on the same hydraulic loop.

Firmer pedal, less effort and travel, stronger brake boost than vacuum can provide, saves space in a time where engine bay space is at a premium, works on diesels where there is no vacuum supply, etc. It's becoming more common (?) in some newer cars. Esp all V8 Mustangs and Cobras, Dodge/GM/Ford trucks, Hummers, diesels, etc.

What kind of car is this anyway? Be nice to know if it even has hydroboost or not, and if not we can drop the subject

 

[SpeedEng66]

well it kinda depends on the noise

take a look at your belts might be slipping

 

[Zenmervolt]

Originally posted by: exdeath
It's becoming more common (?) in some newer cars. Esp all V8 Mustangs and Cobras, Dodge/GM/Ford trucks, Hummers, diesels, etc.

Funny. My 2006 V8 Mustang had a perfectly normal vacuum accumulator.

Hydroboost is interesting, but from what I can tell, rather rare. Certainly not anything I'd heard of until today and from a couple of information sources, it's exclusive to diesel engines and Hummers for currently produced vehicles. Mustangs did use it in their V8 models from 1996-2004, but with the 2005 re-design Ford either went back to a conventional vacuum booster or the 2006 Mustang GT that I had was somehow a one-off custom job that I didn't know about.

ZV