Power Steering Hose Change

[youngbimmer]

I am preparing to order some power steering hoses to replace all 4 of mine (H31 system). They seem to be sweating/wet so in the interest of not having catastrophic failure on the road, it seems right to do it after 32 years. My question pertains to the fluid refill process: I know on my previous 735, there wasn't a bleed procedure per say, just to refill the reservoir and turn the wheel to its limits a handful of times to bleed air. Is it the same process for the H31 (using ATF, no LAD)?

Also pertaining to brake bomb, are there tell-tale signs of it needing replacement? It is original to the car, I'd rather not have sudden brake loss if it goes out.

[CamE32]

Not sure on the PS hoses - although I did change one on my first E32, non-LAD, and don't recall doing anything special.

As far as the brake bomb goes... when you brake suddenly, does the pedal get harder to press? Mine was like hitting a brick wall with my foot if I really needed to get on the brakes - pretty scary. Basically, in my limited experience, you'd know if it was bad. But hopefully someone can share the how-to-check mechanically procedure, though _ I don't have a link saved.

It was totally worth the $$ to replace IMO - I bought this one and gave up on installing it myself the rubber mounts were twisting bad and I didn't have a good way to hold the accumulator steady (+ I think you need a pretty big spanner, with good leverage). Probably another $100 to install, can't remember at the moment.

[CroughtonE32]

I don't have an answer for you, but I love when I learn something here that I never knew. I see you've got an 88 E32. I remember the brake bomb and my power steering interconnected on my E23. I had it from 83 to 90. I remember pumping on the brakes for my mechanic with the power steering fluid reservoir open and watching it come up. I remember replacing the brake bomb a couple of times over those 7 years of ownership, but I had no idea the E32 ever had that power steering/brake system. I guess the very early ones did. It's always a learning experience signing on here.

[youngbimmer]

I don't have an answer for you, but I love when I learn something here that I never knew. I see you've got an 88 E32. I remember the brake bomb and my power steering interconnected on my E23. I had it from 83 to 90. I remember pumping on the brakes for my mechanic with the power steering fluid reservoir open and watching it come up. I remember replacing the brake bomb a couple of times over those 7 years of ownership, but I had no idea the E32 ever had that power steering/brake system. I guess the very early ones did. It's always a learning experience signing on here.

87-88 E32 735 had it, from 89 on it became vacuum booster. It was always present for 750

edit: seems like I found my answer. Instead of pentosin I will be using synthetic ATF
https://www.bimmerforums.com/forum/s...on-and-Service

[CroughtonE32]

Many years ago when I had two power steering leaks mainly from the high pressure hose, I replaced everything at once as well as the pump. Never had a leak since. You ever have a problem with this part. https://www.ecstuning.com/b-genuine-...t/32411134770/

It's a solenoid in back of the steering box. Had to replace that little thing twice because of leaking. Expensive piece. Last one was about 10 years ago.

[shogun]

Instead of Pentosin you can use replacement from Febi Bilstein, they have replacement for the no longer available mineral based CHF 7.1 and the other one is fully synthetic as replacement for CHF 11S. All the online shops have it.

[shogun]

Many years ago when I had two power steering leaks mainly from the high pressure hose, I replaced everything at once as well as the pump. Never had a leak since. You ever have a problem with this part. https://www.ecstuning.com/b-genuine-...t/32411134770/ It's a solenoid in back of the steering box. Had to replace that little thing twice because of leaking. Expensive piece. Last one was about 10 years ago.

when the Servotronic Control Unit is leaking, no need to buy a new one, it is always just the small o-ring for the head of the part which goes into the steering box, that o-ring is not available in BMWs parts lits, but every box of standard o-rings has them, costs you only some cents, just test which oring fits best and install. At the same time clean the mesh filter which sits just above the o-ring, see the pics on the ECS site, on my website under steering I mention the causes of clogged filter screens, steering becomes hard as not enough fluid flow goes thru.
If you still have the old ones, do not throw them away, you can repair them.

[youngbimmer]

Instead of Pentosin you can use replacement from Febi Bilstein, they have replacement for the no longer available mineral based CHF 7.1 and the other one is fully synthetic as replacement for CHF 11S. All the online shops have it.

my 735 does not have LAD, and the reservoir calls for ATF. Is there any benefit to running the Febi fluid instead?

[shogun]

IIRC cars with H31 hydraulic brake booster use Pentosin, even w/o LAD. Here is a 1988 user manual https://750il.bmw7.hu/owners_manual/framed.html
power steering fluid https://750il.bmw7.hu/owners_manual/images/page_063.jpg but there it it is also not 100% clear as also LAD is mentioned with *. And that is based on 1988 fluids, nowadays the fluids are much better, if you take a fully synthetic fluid that should be o.k. Just check the viscosity is similar to Pentosin CHF 11S. Especially important in colder climates. I run the Febi Bilstein stuff and it works well

[youngbimmer]

IIRC cars with H31 hydraulic brake booster use Pentosin, even w/o LAD. Here is a 1988 user manual https://750il.bmw7.hu/owners_manual/framed.html
power steering fluid https://750il.bmw7.hu/owners_manual/images/page_063.jpg but there it it is also not 100% clear as also LAD is mentioned with *. And that is based on 1988 fluids, nowadays the fluids are much better, if you take a fully synthetic fluid that should be o.k. Just check the viscosity is similar to Pentosin CHF 11S. Especially important in colder climates. I run the Febi Bilstein stuff and it works well

I just snapped a photo of my reservoir. It says ATF OIL ONLY. Brake Bomb is just to the left of the reservoir.

IMG_5230.jpg

[shogun]

then use ATF or sythetic power steering fluid, I assume does not matter.

[youngbimmer]

then use ATF or sythetic power steering fluid, I assume does not matter.

I plan to use full synthetic ATF . I will have to see about the servotronic module and cleaning. steering is sometimes heavy at low speed.

[shogun]

there are in total 4 bolts you see on the installed servotronic module, 2 shorter ones which hold the unit together and 2 longer ones which fix the unit to the steering box, only remove these 2 long bolts, here you see them, they have a head for a star tool, the other 2 have a different head https://www.ecstuning.com/b-genuine-...t/32411134770/