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whirring noise at stop - 86 bmw 535i

8K views 13 replies 2 participants last post by  smokey+ 
#1 ·
hi,

at a stop i've got a weird intermittent pumping/whirring sound from somewhere in engine compartment.

my clutch syncros are not good, but this is a different sound. if i pump the brakes it seems to go away. have tried taking foot off the clutch, neutral vs. in gear. seems like related to brakes.

is there a pump or something? low pressure? my brake fluid resevoir seems to be missing any kind of rubber sealer and it leaks out the top of the cap. figure i should fix that. but anybody got any ideas?

hmmm.
 
#2 ·
Your car uses the Power Steering system as a pressure assist to the brake system while the 528e uses vacuum. There is a filter hiding inside the Power Steering fluid (which is Automatic Transmission fluid, Dexron II to be exact) under the mesh. You'll need to de-pressuriize the system by pumping the brakes 10 to 20 times after you shut off the engine before opening the reservoir. There are a couple of circlips holding things in place so you'll need some tools. This should give you a better picture:

http://www.bmwmobiletradition-onlin...el=DC74&mospid=47231&btnr=32_0150&hg=32&fg=20

Good Luck!
 
#3 ·
it's mostly quiet

hi,

it's mostly quiet now.

seems like if i speed up to 50mph or so and then slow down by braking the whirring sound comes back. if i pump the brakes a bit it goes away and then comes back.

i know my brake booster leaks ever so slightly... don't think it does it enough to cause this though...

have checked fluid level in the canister. seems good but i know when the car is running it drops down quite a bit. i do pump the brakes 10+ times with car off before checking the level.

the filter cartridge was still in one piece but holding it up to the light showed it was good and dirty compared to the new one.

any ideas???
 
#4 ·
Power Steering Pump or Brake Booster??

Could it be the Power Steering Pump or Brake Booster???

at a stop i get the whirring sound, if i pump the brakes the noise goes away then ccomes right back.

don't think i have air bubbles in the system, but after replacing filter cartridge i didn't start the car and pump brakes and move steering wheel to supposedly get air bubbles out like my mechanics book says. didn't read about that til today.

sorta don't think that is it though...

anybody have similar symptoms? it sounds like it low on fluid but it's not...
 
#5 ·
I think that you might have a bad or dirty ABS sensor and what you are describing is the ABS system working (that is if your car has ABS!). For a quick check, locate the ABS brain above the glovebox (right above the ECU) and just unplug it. Your dash ABS will remain lit but do some driving around and see if the sound is gone. If it is then your ABS is getting confused by probably dirty sensors or rusted ABS hubs (they look like gears). In order to reach the sensors you will have to remove the brake rotors and thay can be VERY difficult to remove. You can clean them on location with brake parts cleaner (get a couple of cans, you'll need them!). My car has very badly rusted rear ABS hubs (they are exposed to the undercar environment) so the sensors cannot get a good reading.

Good Luck and Happy New Year!
 
#11 ·
hmmm. i'm thinking maybe i should check out the power steering pump? when i got the car from the previous owner they had let the power steering reservoir go empty. i think the brake booster was leaking. i put new seals in that and it seems to be holding fluid these days.

i'm not getting a screech or anything from the steering wheel. i read somewhere that when the engine is running if you have the power steering reservoir cap off (where the atf goes) that you should be able to see the fluid moving around. i don't remember seeing that so much. is it that noticeable?

i did the steering wheel thing and pumping the brakes to get rid of bubbles. just thinking maybe something is up with the pump. i read in my book you can check the pressure with a gauge. i'll see what that says. yey. another expensive part.

not sure about the brake accumulator symptoms? rock hard brake pedal? i'll read about it in my book...
 
#13 ·
The bomb is either working or not so I don't think that is it. Did you bleed the power steering system after replacing your pump? You have to turn the steering wheel from one side to the other a couple of times with the engine running. It is much easier to do if you have the car on jack stands. Then pump the brake pedal like 15 times (it should get hard as a rock) and check your fluid level, it should be close to 1 inch from the top edge of the reservoir.
Good Luck!
 
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