Power steering fluid overflowing when pushing brake pedal!?

[jmile46]

Hey guys, back again. Youll have to bare with me as a I clean up this e32! So I was bleeding new caliper today and then started to notice the red atf leaking out of the reservoir. I noticed a little late as it had already pooled onto garage floor. It appeared that every time brake pedal was pushed it seeped out more.

I checked it the other day and it was very low. Up to the bottom quarter of the reservoir, so I topped it off with fresh atf to just over the screen. Noticed slight seepage overnight but now after bleeding breaks major fluid overspill. When I topped it off last night I never drove car since. I popped off top just now and it was to the brim, still flowing over and I noticed old fluid in with it. So what the hell is happening? Is the brake booster somehow tied into this or what? Does fluid leave the pump when sitting? When I filled it, car was still warm.
Any ideas??

Edit: I should also add that the first 2-3 minutes of cold start the power steering sounds awful. It groans and grinds very badly. I thought super low fluid was the cause.

[shogun]

Tell us at least which E32 , year and month you have.
Vacuum brake booster or H31 hydraulic brake booster like on the 750 and oldest 735?


first 2-3 minutes of cold start the power steering sounds awful. It groans and grinds very badly. I thought super low fluid was the cause.>>>>> that is usually with too low fluid level and it sucks air and start foaming = overflow

[jmile46]

Tell us at least which E32 , year and month you have.
Vacuum brake booster or H31 hydraulic brake booster like on the 750 and oldest 735?


first 2-3 minutes of cold start the power steering sounds awful. It groans and grinds very badly. I thought super low fluid was the cause.>>>>> that is usually with too low fluid level and it sucks air and start foaming = overflow

Oops Im an idiot. 1988 735i. Month Im not sure off top of my head. The fluid was definitely low and because of this it was foamed up very badly. Why Im confused is that I topped it off to above the mesh and literally everything I topped it off with looks to have come out when bleeding brakes. Is there a wrong way to top off fluid or something?

[shogun]

As we do not know the VIN, let's say it is a 01/88 735 automatic, that could have hydraulic brake booster or a vacuum operated http://www.realoem.com/bmw/enUS/part...BMW-735i&mg=34
In case hydraulic, then also the brake booster needs power steering fluid as you can see in the diagrams, and the power steering pump is a double pump
Anyway, first fill up the power steering fluid, start the engine, turn steering wheel 3-4 time right/left to the end, fill up reservoir if necessary. Then see what happens.

[jmile46]

As we do not know the VIN, let's say it is a 01/88 735 automatic, that could have hydraulic brake booster or a vacuum operated http://www.realoem.com/bmw/enUS/part...BMW-735i&mg=34
In case hydraulic, then also the brake booster needs power steering fluid as you can see in the diagrams, and the power steering pump is a double pump
Anyway, first fill up the power steering fluid, start the engine, turn steering wheel 3-4 time right/left to the end, fill up reservoir if necessary. Then see what happens.

Without checking vin, I can tell you this is what the power steering reservoir looks like.

Im not sure if this is different between other version. But Ill do that tomorrow. Just scared of it overflowing again. Im most confused as to where the additional fluid came up from that caused it to overflow so much. Air in system?

[shogun]

Maybe you have a hydraulic brake booster and you pumped many times for bleeding, then the brake bomb gets empty and pushes the fluid to the reservoir. When you then start the engine, the brake pedal will drop down and the bomb will be filled again = reservoir lower. Does it look like this? http://www.realoem.com/bmw/enUS/show...diagId=34_0302

Description of the H31 system
http://www.bmwccae31.com/DOCS/Info/B...t%20System.pdf
https://www.bimmerforums.com/forum/s...teering-system
The H31 brake booster system uses Pentosin, and that is light green, not red ATF.

Based on the VIN add the car data to your profile, then we can help better.

Anyway, refill tomorrow again and turn the steering wheel with engine on and refill if required.

[jmile46]

I can tell you for sure it takes atf. Off top of head I can’t tell ya what full system looks like. But my buddy just gave me some duh! Insight. So i filled fluid, never drove or moved car. Then replaced front brakes and was turning the wheel to access calipers better. So I had been turning wheel with system off, and I think I overfilled it, so correct me if wrong but that would push fluid up!

[rosakirk12]

Takes Pentosin

[jmile46]

Takes Pentosin

The cap on top says atf only.

[CroughtonE32]

Eric, that picture looks like the brake system I had on my 1983 733I E23. Used ATF only and shared fluid with power steering. I remember having to replace that nitrogen ball a couple of times during the 8 years I had the car. I remember when bleeding the brakes, took the cover off pumped the brakes and watched the fluid come up. I forget the exact sequence they used, but I do remember them turning the wheel from side to side a few times. I never knew that brake system came on any E32. Even the very early ones.

[shogun]

Early E32 730/735 M30 used the H31 hydraulic brake system like the E23 and E24, and all E32 750. Maybe it uses ATF (not sure), the 750 use Pentosin because of the self levelling rear suspension system requires that

[jmile46]

So does that mean the brakes used atf? Because my brakes use brake fluid. Sorry but a lot of this stuff goes over my head. Im very new to these pre 2000s bmws.

[shogun]

The brake always use brake fluid, only the hydraulic H31 brake booster system uses Pentosin or ATF, separate systems. Explained here http://www.bmwccae31.com/DOCS/Info/B...t%20System.pdf
Later E32 735 use vacuum assisted brake boosters.

[jmile46]

Ahhhh. Figured. After checking out the engine bay I believe this is the system I have, as I recognize the nitrogen ball.
IMG_0867.jpg

So this is the hydraulic system then?

Edit: just noticed the get a polish girlfriend ad at top of that picture, LOL!

[shogun]

Yes, that is the H31 hydraulic brake booster system. In case the brake booster is leaking thru the weep hole between brake booster and brake master or if the sealings inside are bad, you can contact our member master6, he repairs them. New hydraulic brake booster costs almost more than the car is worth.

[jmile46]

Well fingers crossed its not leaking. Im thinking it was my fault it overflowed. Ill try again tomorrow!

[youngbimmer]

I have the same problem, I overfilled it because when I checked the reservoir, it appeared to be low, but I did not press brake pedal to return fluid into the reservoir, so I overfilled. Kinda wish I had my vacuum brake booster from my '89 but apparently in some cases, the hydraulic booster is "better performance". It can also leak from cracked plastic surrounds at the pressure sensors that hook into the reservoir.

[jmile46]

[QUOTE=youngbimmer;30160513]
So what did you do to fill it properly? Do I have to pump brake pedal then check fluid ?

[shogun]

with running engine fill just below the strainer. Or with engine off, pump the brake pedal abt. 20 times till it get's hard and the fluid level in the reservoir will rise, then it should be max. abt. 25mm below top of the container respect. not overflow. When you then start the engine, the level will go down again, as the brake bomb will be filled.

http://www.bimmerboard.com/members/q...0Reservoir.jpg
As my iL has self levelling on the rear, I even fill the reservoir less, about 1 inch below the strainer with engine running, because for the case that I lift the rear and the SLS shocks are cpl. extended, all the fluid from the SLS will flow back thru the regulating valve into the reservoir, and that can cause overflow, if too much filled.

[jmile46]

Thank you! So Ill fill just below strainer when engine is running. Hoping to get to it today. Been busy and haven’t messed with 7 series past couple days.

[jmile46]

Well I filled reservoir to just below strainer. Took if for a drive and the pump was groaning and grinding as much as ever. I got home to see that it overflowed again. This time not as much and after some more driving seemed to stop overflowing. Got back and parked it and checked fluid to seen it just above strainer. I turned it on again and noticed everytime I pump brake pedal fluid rises, and every time I turn the steering wheel fluid goes down, but once full lock and holding it rises up again. Meanwhile every turn of the wheel it groans horrendously. Im at a loss here, as I truly don’t understand what the hell is happening. Tonight im going to read the explanation of the system. The fluid is foamy up top. Is there air that needs to be bled? Is my pump toast?
IMG_0883.jpg

[shogun]

The power steering system bleeding is done automatically when the engine is running and the steering wheel is turned left and right several times.
The pump noise could be caused by worn seals inside the pump when metal and metal is touching. There are seal kits available for the pump. Also master6 repairs them.
It could also be that the old hydraulic hoses are internally 'swollen', same like old brake lines.

[jmile46]

I may have to look into that. Because topping it off with fluid doesn’t seem to be making the noise go away. However its does get better after some driving and warmed up. Could that point to something else?

Edit: I realized that I actually have a power steering pump laying around from another m30( out of an e34 535i) if its the same I think I’ll swap it in and see what happens.

[shogun]

First change or clean the filter inside the reservoir. That filter is at the bottom of the strainer and held by a snap ring on the center pin/bolt inside the reservoir. That filter can be clean with brake cleaner. Looks like this, also see realoem
https://www.bimmerforums.com/forum/s...tal-reservoirs
If it goes away after some time, that means at the beginning there is not enough fluid inside the pump, so the pump might be still o.k., but the flow to the pump not.

[jmile46]

There is hope!!! Thank you for sharing that! Certainly going to give it a shot. Can I pull it up with fluid still in reservoir though? It said recommended in post.