MyE28.com

Primary symptoms:
-Power Steering (PS) is intermittent after pump rebuild, bomb swap, & bleed.
-Pump whine is less after rebuild, tho still present & also intermittent.
-PS filter is NLA, unable to swap

Full story:
Since I got the car (5/24), PS has always worked, tho very whiney & noisy. Brakes also worked, tho, as I learned, the brake bomb was toast.

2 weeks ago the OE pressure hose from the PS pump up to the valve body ruptured, so I replaced that, & replaced the break bomb as well.

Also picked up the OE PS pump rebuild kit.. new seals & grommets all around. Pump internals look good, besides (& worth noting), I noticed the sleeve/bearing that is pressed into the PS pump housing is worn & out of round (crude reman from 2013 with very low miles).

All relevant fittings and fasteners have been checked, rechecked & appear good. No visible ATF leaks.

OE PS filters are NLA, so I did not remove, inspect or replace.*

I followed the bleed steps outlined here: https://www.youtube.com/watch?v=YDNTygiDhRk

After the initial bleed, the whine quieted down nicely. Then, after pumping the breaks a number of times the whine returned, intermittently. Engine revving or light taps on the brakes will quiet it back down... whine seems to come and go... when it does quiet down, its much much quieter than it was when I got it. Despite the noise, PS actually worked before that line burst!.

When I took the first test drive, break assist was good. However, power steering function remains intermittent at best.. occasionally works, most times not... WTF!? Tho noisy, PS worked fine before the line burst & I thought I bled effing this thing!

*Asterix:
As stated, I did not replace or remove the PS filter.. Randomly though, I noticed that when I tipped the reservoir's central rod to the side a little, I think it breaks the seal on the filter and i get an inrush of fluid to the can and the whine quiets down right away.

Conclusion:
Now thinking the filter may be plugged and not allowing enough flow, which may be taxing the pump and contributing-to/creating the issue. PS filters are NLA and not seeing anything aftermarket available anywhere (I found one Romanian site selling something that looked as equal, but no shipping to the western hemisphere, so still searching).

Questions:
-Are the steps I followed to bleed correct?
-Why am I getting good brake boost but no power steering (except sometimes)?
-Could these symptom relate to a clogged PS filter?
-Can I pull the filter and clean, bake, or otherwise refurbish it?
-Does anyone have a NOS filter they want to sell (p/n 32411128167)?
-Honestly, do I really need a PS filter on a 40yo e28?
-Can the PS pump housing sleeve/bush/bearing be replaced?
-Will I need to tear into the steering box next?
-Can anyone offer any other thoughts or advice?

Much Obliged!

You can get the PS filter here: https://www.amazon.com/dp/B09D55G3RW

You MUST trim it to length to match the old filter. I suggest using a fine tooth saw.

jayjaya29 wrote: Aug 08, 2024 7:54 AM You can get the PS filter here: https://www.amazon.com/dp/B09D55G3RW

You MUST trim it to length to match the old filter. I suggest using a fine tooth saw.

I was thinking, "Ivo on Amazon"...

Ok thanks for the link to the amazon filter... Ordered.

I realized the compression spring (32411128169) is missing from my PS reservoir assembly & will need to replace..

Perhaps no spring is part of the problem?.. I kinda think not, as its been MIA as long as I've been the owner & PS was good until the pressure hose blew.
I think the spring just holds down the filter/cap to complete the seal & also think the flow direction is from the outside inward, so suction alone should hold it in place, mostly...?

Is the rationale for re-sizing the new filter so the stack height with the spring & everything adds up correctly?

I wonder if we could use the taller filter if I used a shorter spring to accommodate... hmm

Also now thinking about some kind of in-line filter retrofit, on the main return line.. has anyone tried this?

1st 5er wrote: Aug 08, 2024 8:49 AM

jayjaya29 wrote: Aug 08, 2024 7:54 AM You can get the PS filter here: https://www.amazon.com/dp/B09D55G3RW

You MUST trim it to length to match the old filter. I suggest using a fine tooth saw.

I was thinking, "Ivo on Amazon"...

Ivo is out of stock right now.

Back in Business!

Seems the lingering issue, after PS Pump rebuild, pressure line & bomb swap, really was a clogged PS filter after all.

With the OE filter installed, the pump would labor heavily, straining the entire system & whining really loudly.

By accident, I noticed that when I bumped the central reservoir rod to the side a little, it would break the filter seal and the whine would immediately cease. Pulling the filter quieted everything down and PS function is now 100%

I read at least one forum post somewhere where a claimed BMW tech said "if the fluid is clean, pull the filter". So, I did that and its working just perfectly!

The system had just been completely flushed, so I felt safe pulling the OE filter and running without it for now. I still have the Hino #S443611070 on order & will trim to 35mm before installing, as advised.

Side note, the reservoir spring I said was missing in an earlier post is actually present.. the reservoir is just a lot deeper than I had realized!

Double side note: Heres a pic of the toasted OE PS Filter--OOF! Wondering if a in-line filter on the main/low-pressure/return line is a viable retrofit...

As a stop gap measure, & while I wait for the new filter to arrive, I stuck a high power Neodymium magnet on the outside of the reservoir can, right above the primary/low-pressure PS return line. This "should" capture any hard/ferrous particles that may be floating around while the filter is MIA.

When I Install the new filter, I'll pull the magnet, clean the can thoroughly, then flush & re-bleed the entire system for good measure.

I haven't really investigated much into this, but Mercedes used to use a similar ring filter in their PS reservoirs and the updated cartridge style filter is a retrofit for the earlier reservoirs with the ring filter. Would they also fit the BMW reservoir? I'd ASSume that they'd be similar in size/function being from Vickers/ZF?

Kerrvillian wrote: Aug 09, 2024 5:58 PM I haven't really investigated much into this, but Mercedes used to use a similar ring filter in their PS reservoirs and the updated cartridge style filter is a retrofit for the earlier reservoirs with the ring filter. Would they also fit the BMW reservoir? I'd ASSume that they'd be similar in size/function being from Vickers/ZF?

Interesting.. can you provide any part numbers fort he Mercedes components?

joeuser999 wrote: Aug 09, 2024 6:08 PM

Kerrvillian wrote: Aug 09, 2024 5:58 PM I haven't really investigated much into this, but Mercedes used to use a similar ring filter in their PS reservoirs and the updated cartridge style filter is a retrofit for the earlier reservoirs with the ring filter. Would they also fit the BMW reservoir? I'd ASSume that they'd be similar in size/function being from Vickers/ZF?

Interesting.. can you provide any part numbers fort he Mercedes components?

The Mercedes filter can be found here:
https://www.autohausaz.com/pn/0004662104

The original ring style is so obsolete it's impossible to pull a part number for. MB went to the pleated filter in the early 80s and the same part retrofits on the earlier pumps from the 70s and early 80s with the ring filter.

Again.....no idea if it's a solution for the BMW, but maybe worth a try? Maybe someone's tried it and has feedback?

not being even remotely familiar with this arrangement, can you just ditch the stock filter and use a generic in-line filter on the suction side of the pump? They exist in a form similar to fuel filters, but made of metal so they aren't so inclined to split open and spray fluid on hot engine parts. Some of them also have magnets in them to grab any steel/iron shavings.

Ok, after solving this problem, I'm happy to report the HINO filter (#S443611070) is working perfectly.. Initially I took previous advice from this thread that one "must" trim the height of the Hino filter to 35mm, & I did, in fact, trim the height of the Hino filter to 35mm..

However, now I can confirm that the HINO filter does in fact work, and that there is no real value to trimming the height.. Sure the OE was filter 35mm tall.. However, there is no groove cut in the PS reservoir retention rod that forces us to position the spring retainer clip at any specific height... So, in truth, you can run the hino filter without needing to trim its height.

Honestly, if you want to be bone stock/oe/genuine, trimming the height is easy enough, however, in the end it really is unnecessary. You can run the Hino filter as-is, and just position the spring retention clip at the correct height for the taller filter... Who cares if its taller.. in theory an unmodified Hino filter offers improved filtering capacity and improved flow rate since the element has more surface area..

Again, there is plenty of room in the reservoir for the Hino and trimming the height is unnecessary...just run it.

Side note, since these were low stock on amazon and NLA via BMW, I bought up the remaining amazon stock... Perhaps that amazon vendor will restock.. if not message me and I may be willing to part ways & wont charge a cent more than I paid.

Oof! Amazon unable to ship the filters I ordered.. seems like I got the last physical copy & my order for the remaining stock is in perpetual limbo.. If they EVER ship the filters, I will re-post here for anyone who needs one.. For the moment, looking like I may have gotten the last IRL Hino filer in existence. ¯\_(ツ)_/¯

Side note, after installing the Hino filter, etc.. now getting a perpetual BRAKE light at the dash.. something is causing the pressure system to not build full pressure.. Doubt its the filter per-se...

Even after swapping in a new brake bomb and a full pressure system flush/rebuild, now my brake light is perpetually on and on heavy braking i can feel the brake bomb isnt providing max boost and i can feel the PS pump building pressure at the pedal... Better than before the bomb-swap, still far from ideal and the brake light is mostly always on. :/