Power Steering/Break system failing ‘85 635csi

Post in this forum for topics relating to suspension, steering, and brakes

Moderators: GRNSHRK, ron, bfons

Post Reply
Mike_635csi
Posts: 7
Joined: Thu Apr 02, 2020 2:41 am
Location: Miami, Florida

Power Steering/Break system failing ‘85 635csi

Post by Mike_635csi »

When i purchased it, the previous owner said he had recently replaced the break “bomb”(accumulator) & also replaced the high pressure hose that connected the pump to the break bomb. The whining noise was insane at first, but soon went away.

Driving the car home, the high pressure hose cracked on the cuppling that goes screwed into the accumulator, almost certainly from being screwed too tight.

The pressure hose was replaced & the system was refilled & bled. However the same high pressure hose vibrates violently & gets extremely hot while continuing to make the whining noise consistently.

Aside from these symptoms;
- when the whining& vibrating does disappear, breifly, all it takes is a pump of the breaks to get the pressure hose vibrating/whining again.
-The steering wheel is ridiculously stiff.
-The brakes are very weak & have to use a lot of force to pump pedal.
-the brake on one of the wheels seems to get stuck & causes the annoying scraping noise.

Where should i start diagnosing this issue?
User avatar
86_6series
Platinum Member
Platinum Member
Posts: 1069
Joined: Mon Apr 02, 2007 10:08 pm
Location: West Nyack, NY

Re: Power Steering/Break system failing ‘85 635csi

Post by 86_6series »

I think your pump definitely has a problem.
I would contact Jay Stratton and tell
him the overall symptoms, he'll advise you
on what to do. He's the pump guru.

viewtopic.php?f=24&t=28245
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
Mike_635csi
Posts: 7
Joined: Thu Apr 02, 2020 2:41 am
Location: Miami, Florida

Re: Power Steering/Break system failing ‘85 635csi

Post by Mike_635csi »

86_6series wrote: Tue Apr 14, 2020 11:12 am I think your pump definitely has a problem.
I would contact Jay Stratton and tell
him the overall symptoms, he'll advise you
on what to do. He's the pump guru.

viewtopic.php?f=24&t=28245
Thanks for the lead! I’ll be reaching out for sure!
User avatar
wogden700
Posts: 36
Joined: Fri Mar 08, 2019 3:39 pm
Location: Massachusetts

Re: Power Steering/Break system failing ‘85 635csi

Post by wogden700 »

"noise" in a hydraulic system is usually a sign of pressure or flow rate being to high.
1985 635CSi Diamondblack/Llama
1991 750iL (sold)
Mike_635csi
Posts: 7
Joined: Thu Apr 02, 2020 2:41 am
Location: Miami, Florida

Re: Power Steering/Break system failing ‘85 635csi

Post by Mike_635csi »

wogden700 wrote: Wed Apr 15, 2020 12:55 pm "noise" in a hydraulic system is usually a sign of pressure or flow rate being to high.
How would i address this issue?
User avatar
Ralph in Socal
Platinum Member
Platinum Member
Posts: 2746
Joined: Tue Apr 14, 2009 3:32 am
Location: High Desert of SoCal

Re: Power Steering/Break system failing ‘85 635csi

Post by Ralph in Socal »

I think your problem is the hydraulic distribution block. The part that carries the bomb and distributes fluid to the brake booster and steering box

That unit has very small orifices that will easily clog and prevents fluid flow

I had an issue with one years ago where I had good steering but terribly stiff brake pedal without much stopping power. I was lucky I had a spare on the shelf. Good luck

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)
Mike_635csi
Posts: 7
Joined: Thu Apr 02, 2020 2:41 am
Location: Miami, Florida

Re: Power Steering/Break system failing ‘85 635csi

Post by Mike_635csi »

I finally remembered to test the bomb before starting the engine & noticed the PS fluid in the reservoir did not fluctuate at all. I guess that narrows it down to the pressure regulator or the bomb... hopefully.
Post Reply