Power steering system on '87 535i e28?

afireinside1988 · Post by **afireinside1988** » Nov 04, 2011 7:56 PM

Hi I'm new to mye28.com and I really need some help understanding how my power steering system works. Is the brake and power steering system integrated? What kind of fluid do I need to use? And I have a bad whining coming from my pump when I start it in the cold, especially in the morning. Sound goes away after about 20 secs and steering is tight and great. There is no sound when I turn, just early, cold starts when it whines. Any help would be greatly appreciated.

mooseheadm5 · Post by **mooseheadm5** » Nov 04, 2011 8:01 PM

Quick answer:
Yes, the power steering and brakes are integrated
Use ATF (Dexron III)
When you fill it, make sure not to overfill it. You must first pump the brake pedal 20-30 times until all the residual pressure is gone. Then you can top it up.

Now, do a search on this site. You can use the term "hydroboost" or "hydro boost" and you will get info on how it works.

Welcome to E28 ownership. Check the Tech FAQ section and always search before you post a question. They have pretty much all been answered.

afireinside1988 · Post by **afireinside1988** » Nov 04, 2011 8:15 PM

Wow, that was a quick response! I need to drain the current fluid in there then cause I put dot 3 brake and I'm sure that's not okay. Any suggestions on this? I'm planning to do all this tomorrow. Just replaced rotors and pads all the way around and bled the brakes. Brakes work amazing and no weird sounds other than the brief whine from steering pump.

mooseheadm5 · Post by **mooseheadm5** » Nov 04, 2011 8:22 PM

You put brake fluid in the big metal can or in the small translucent white bottle with the plastic screw top?

The big metal can holds the ATF for the power steering and brake boost system, the plastic bottle holds brake fluid for the actual braking system.

TSMacNeil · Post by **TSMacNeil** » Nov 04, 2011 8:24 PM

Change the fluid. The pump whine may indicate that it's pulling air into the system through a loose hose fitting. It can also be caused by the bolts on the pump case itself getting loose. Tighten those pump case bolts and snug all the hose fittings.

afireinside1988 · Post by **afireinside1988** » Nov 04, 2011 8:27 PM

Thank you so much for your time! This site really is amazing.

mooseheadm5 · Post by **mooseheadm5** » Nov 04, 2011 8:28 PM

afireinside1988 wrote:Thank you so much for your time! This site really is amazing.

Did you read my last post?

afireinside1988 · Post by **afireinside1988** » Nov 04, 2011 8:33 PM

I put it in the metal cannister. The fluid in there before was clear just like brake fluid and when I was bleeding the brakes fluid was coming out from the metal one. I was very confused. So I need to make sure brake fluid is in the brake reservior and the metal cannister is atf 3? I'm confused how this is an integrated system with two types of fluid. I apologize for not knowing a whole lot about these cars. Thanks for your time!

TSMacNeil · Post by **TSMacNeil** » Nov 04, 2011 8:37 PM

Search button is your friend. I'd give a good ear to Moosehead, he has mad skilz.

mooseheadm5 · Post by **mooseheadm5** » Nov 04, 2011 8:42 PM

Well the actual brake system that moves the brake caliper pistons uses brake fluid like all hydraulic brakes. Simple. The hydroboost system uses stored hydraulic pressure to assist your braking efforts. This pressure is produced by the PS pump and stored in the black ball (brake bomb). Some pressure is released whenever you pump the pedal to give you power assist. You only thought fluid was coming out of the metal can when you were bleeding the brakes. In reality, the fluid bled from the brakes comes from the plastic bottle on the master cylinder (to boot, if you have a 5 speed, it uses this same fluid for the clutch hydraulics.)

Anyhow, to flush the system, do not start the car. You will want to pump the system down (press the brake pedal 20-30 times.) Then pull the hose off at the lowest point in the system (the pump) and drain it into a pan. You can move the steering wheel back and forth to push more fluid out of the system. Check the PS pump bolts as TS suggested then reconnect the line. Fill the system, turn the wheel back and forth a bit and set the level pretty much even with the bottom of the screen. As soon as you start the car it'll suck fluid out of the metal reservoir. If you are worried, you can do another drain before the final fill. Always set the final level with the car off and after the system is pumped down.

afireinside1988 · Post by **afireinside1988** » Nov 04, 2011 8:53 PM

That makes much more sense now. I'll get going on this project tomorrow, using your instructions. I really appreciate the help. I love this car, best BMW I've ever owned so I plan to keep it. Thanks guys!

TSMacNeil · Post by **TSMacNeil** » Nov 04, 2011 8:57 PM

I sense the force in this one....welcome to the madness. As always with new guys, please research before you ask as it's all been covered before...make use of the FAQ section. Please be very specific in your questions to include what you've done already in your fix attempt, and be clear when describing symptoms...it saves everybody time that we would rather spend arguing with each other.

afireinside1988 · Post by **afireinside1988** » Nov 04, 2011 8:59 PM

Haha

will do. Goodnight. I'll be visiting you all soon!

TSMacNeil · Post by **TSMacNeil** » Nov 04, 2011 9:02 PM

We take a little getting used to...that is certain.
Please add your specific model/year/car to your sig as it helps everyone know what we're talking about.

see ya

afireinside1988 · Post by **afireinside1988** » Nov 05, 2011 5:23 PM

Flushed the power steering system per moosehead's instructions today. Filled with atf 3 and tightened pump bolts. Everything is sound. Thanks fellers!!!

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