Power Steering Fluid Question

[GVR]

Hi, I'm new here. I've owned my M3 for about 5 years now. When I first bought it I did all the routine maintenance including flushing the power steering fluid. Not sure what fluid was in there, but it was dark gray and really dirty. It took several flushes to get it nice and clean. Fast forward a couple years and my pump started making noise. Not the typical pump whine, but more like a bearing going out type of whine. I did the rebuild kit and it didn't change anything. Tried buying a new pump several times and either no one had one or I was sent the wrong pump. Drove around with a whiny pump for at least a year until I bought a shorter belt and just bypassed the pump. 6 months of driving around like that and I finally found a pump. Different than what came off my car, but it fit. I've had that pump on my car for 2 days and its starting to make that same whine. Sorry for all that, I just want you to understand my frustration at this point.
Now on to my question. The Bentley manual says the power steering system uses Dexron III ATF, that is no longer made. I have been using DEX/MERC ATF as I have read it is the equivalent to Dexron III. Is DEX/MERC the correct fluid, if not, what are you guys using?

[bluptgm3]

The ZF power steering pump (PSP) is the only pump that correctly fits the alloy cap oil filter housing (OFH), of which there is a rebuild kit. The plastic cap OFH compatible PSP miss-aligns when installed on the alloy cap OFH.
The ZF pump has no internal bearing, the pump shaft is bathed in ATF (GL-4 lubricant), riding on a film of ‘oil’ in the aluminum housing.
I have seen references to rebuilt ZF pumps in the supply chain, again.
I have experienced a lazy hydraulic/compression spring tensioner. The tensioner assembly pivot bearing is not sealed and can seize due to contamination. A lazy tensioner allows the belt to slip and that makes noise.

The E36 power steering system uses ATF, specifically a Dexron III compatible fluid.
I use RedLine D4 ATF .

DEX/MERC ATF states -
“Helps provide smooth shift performance where DEXRON-III or a MERCON fluid is specified”


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[TostitoBandito]

I too use redline D4 ATF, but basically any modern dextron ATF fluid should be fine. Just as long as you don't use "power steering fluid", which is generally different. Don't think the fluid is your issue.

Things to check:

• main belt and all pulleys for any damage or squeaking/whining
• the steering rack for any leaks or damage
• ensure that the PS reservoir and all lines flow freely and are connected properly
• lastly, I guess buy a kit and rebuild your original PS pump yourself to be certain; they do wear out and require rebuilds after a while, and you have no idea of the condition of what you replaced it with either

[82bmw633]

I buy Dex/Merc III at local auto parts stores (AutoZone, Advance Auto Parts). It’s still available.

The PS reservoir has a non-replaceable filter. You should probably replace the reservoir. Is the rack making the noise or is it the pump?

[NeilM]

I buy Dex/Merc III at local auto parts stores (AutoZone, Advance Auto Parts). It’s still available.

I've been using Mobil 1 Synthetic ATF in the ps system since forever. Works fine, available anywhere.

The PS reservoir has a non-replaceable filter. You should probably replace the reservoir.

Can be back-flushed to clean in a pinch.

Is the rack making the noise or is it the pump?

Or even the belt tensioner pulley?

Neil

[AJLM34A]

#'s 6 & 14 have bearings and will make squealing/groaning noises and are not serviceable, replace only. # 5 is two needle bearings that can be relubed but if you have a lot of miles, get # 20 since it includes the tensioner. INA makes good replacement parts of these.

Screen Shot 2020-09-09 at 12.21.44 PM.png

[bluptgm3]

INA makes good replacement parts of these.

INA was/is the OE supplier to BMW. Note the BMW Rondel logo cast in the INA pivot bracket.



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[GVR]

Thanks for all your comments and suggestions. When the pump started making noise about 2 years ago, I rebuilt it with the $40 kit you can get at ECS. When that didn't fix it, I replaced everything in the power steering system except for the rack. It still made noise, so I did all the pulleys, both tensioners and new belts. When it still made noise after that, I bypassed the pump with a shorter belt and the noise stopped. I've been over the system many times and have never seen a leak. I think I will pull off all the hoses and cooler this weekend and give them a good flush. Couple questions.
--Could there be an issue with the rack that would make the pump whine? I've been wanting to do the ZHP rack swap.
--Would there be any harm in removing the restrictor in the hose going to the resivor?

[frbz]

Did you change the fluid reservoir? If not then do that first. It may well be your issue. It was my issue. Funny grinding nosies coming from the pump initially only after a hard braking maneuver, and would settle after a period of time or a restart and getting progressively worse. Replacing the reservoir fixed it. I used Mobil 1 ATF.

[das borgen]

Thanks for all your comments and suggestions. When the pump started making noise about 2 years ago, I rebuilt it with the $40 kit you can get at ECS. When that didn't fix it, I replaced everything in the power steering system except for the rack. It still made noise, so I did all the pulleys, both tensioners and new belts. When it still made noise after that, I bypassed the pump with a shorter belt and the noise stopped. I've been over the system many times and have never seen a leak. I think I will pull off all the hoses and cooler this weekend and give them a good flush. Couple questions.
--Could there be an issue with the rack that would make the pump whine? I've been wanting to do the ZHP rack swap.
--Would there be any harm in removing the restrictor in the hose going to the resivor?

Link to this kit on ECS please?

[shogun]

Power Steering Pump Gasket Kit, All the gaskets needed to rebuild your power steering pump, Brand: Genuine BMW - Corporate LogoES#: 54545Mfg#: 32411135880 13% off MSRP $54.35 ,$47.22
Usage E30,E36,E28,E34,E24,E32,E31,Z1

[bluptgm3]

Link to this kit on ECS please?

32411135880

You know about realoem.com, correct?
Use the last seven characters of your VIN to target your cars build.


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[sirhodjibob]

To add another fluid recommendation, I use Liqui Moly top tec 1100 ATF. Pump is nice and quiet.

[GVR]

Again thank you for the comments. The Mobil 1 ATF looks pretty easy to get, I'll have to try that. I haven't heard of the Liqui Moly top tec 1100 ATF so thank you for that.

--frbz-- Yes I replaced the reservoir when I did everything else and it still look good

--das borgen-- https://www.ecstuning.com/b-genuine-...t/32411135880/

--bluptgm3-- I have heard of realoem.com. ECS Tunning and FCP Euro have been my go to's for years, never had a problem with either place. My wife drives a Mini, I have bought a lot from both of these places.

[bluptgm3]

ECS Tunning and FCP Euro have been my go to's for years, never had a problem with either place. My wife drives a Mini

Ya, just don’t rely on a vendor website for correct parts for your VIN.


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[das borgen]

You know about realoem.com, correct?
Use the last seven characters of your VIN to target your cars build.


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Of course I'm aware of realoem and the ETK. But I just didn't remember a rebuild kit was sold by BMW and officially listed in there. That's good to know!
I say remember, because I made a thread 9 years ago about rebuilding and I even had the BMW part number in there LOL

https://www.bimmerforums.com/forum/s...mp-rebuild-DIY


I guess I'm to the point there I've forgotten more stuff than newbies know. OMG

[GVR]

--Update--

I've been driving my car for a week now and my pump is nice and quiet. I did 3 things,
-I flushed the system with new ATF, however, the fluid that came out looked just as good as the fluid that went in.
-I switched from Valvoline DEX/MERC to Castrol DEX/MERC.
-I removed the restrictor from the low pressure line.
Not sure which one of these fixed my problem, but I'm happy its fixed.

[bluptgm3]

My understanding of the purpose of the restrictor is to prevent foaming (or condense the foamed fluid) of the fluid returning to the reservoir. The foaming fluid in the reservoir will cause cavitation of the pump and the expansion of the aerated fluid to over flow from the reservoir.


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[GVR]

I've read that too. I've been checking the reservoir for any spillage or foaming and haven't seen any. I have done several pulls to redline and everything looks good. I may take it on my favorite twisty road this weekend and give it a good workout. I'll report back if I have any issues.

[jayjaya29]

According to some internal BMW documentation I have, the restrictor in the low pressure line is ONLY to reduce a groaning noise made by the PS system in certain situations.

[SG_M3]

According to some internal BMW documentation I have, the restrictor in the low pressure line is ONLY to reduce a groaning noise made by the PS system in certain situations.

I would believe it. Since going to the chase bays there is a groan produced from the PS system.

[GVR]

Good to know, thanks