BimmerFest BMW Forum banner

1 - 20 of 29 Posts

·
Registered
Joined
·
105 Posts
Discussion Starter · #1 · (Edited)
For my 540iT.

I thought I was going crazy, but I have noticed on a few rare occasions that when I make a turn with RPM's around 3500, the wheel almost locks up/takes a lot more force to turn. Sounds like the PS pump may be going out, but why would it do this only around this RPM range. I tested it in the parking lot today and sitting motionless, rev car to 3500, and voila, steering gets stiff. Let throttle down, and steering comes back to normal. Any other ideas as to what it might be. For the price of a new pump and either my time or a mechanics, I can live with it for now. THoughts...
 

·
Older than old school
Joined
·
4,461 Posts
First of all, can we assume you checked the power steering fluid level? Good. Did the fluid smell burned? Does it look discolored? If so, you might try suctioning it out and refilling it, running it, and then repeating the process another time or two. If the fluid looks normal, then the only other problem I can think of would be the accessory drive belt and tensioner. Maybe it slips under load.
 

·
Registered
Joined
·
105 Posts
Discussion Starter · #3 ·
Yes, I just changed fluid out about 6 months ago with Redline ATF. Old fluid looked old but new stuff still looks new. I do have to clean the top of the reservoir every once in a while as it builds up fluid and dust. Dont know why it so much gets spit up out of the hole in the cap if that is what it is for...
 

·
Seek to understand,^Value
Joined
·
25,199 Posts
I do have to clean the top of the reservoir every once in a while as it builds up fluid and dust. Dont know why it so much gets spit up out of the hole in the cap if that is what it is for...
We solved that already. It is the o-ring. It goes bad after about something like 10 or 15 openings of the power steering fluid reservoir cap. Keep a spare on hand (better than the M-sock mod).

- How to fix the wet power steering reservoirs due to poor O-ring design (1) (2)


 

·
Registered
Joined
·
591 Posts
Yes, I just changed fluid out about 6 months ago with Redline ATF. Old fluid looked old but new stuff still looks new. I do have to clean the top of the reservoir every once in a while as it builds up fluid and dust. Dont know why it so much gets spit up out of the hole in the cap if that is what it is for...
It's a breather hole, but it should not spit up fluid.

How many miles on your car? Did you change the reservoir as well when you changed the fluid as it has a built-in non-replaceable filter?
 

·
Registered
Joined
·
5,860 Posts
At high RPM it's pretty normal for some PS fluid mist to come out of the vent hole in the side of the cap. To keep most of the mist inside I cut off the cotton tip from a Q-tip and stuck it in the vent hole. Give it a try, it work well.
Your PS pump is heading for failure, at high RPM's you are loosing pressure which makes it hard to steer.
You could try to open the pump up, flush it out with gas and see if all of the vanes are clean and free to move in the impeller.
The broken mounting tabs are the result of my water cooled alternator seizing and the belt ripping the pump off. I got a used one for ~$175 iirc, new was $400 at the time.
 

Attachments

·
Registered
Joined
·
105 Posts
Discussion Starter · #8 ·
It's a breather hole, but it should not spit up fluid.

How many miles on your car? Did you change the reservoir as well when you changed the fluid as it has a built-in non-replaceable filter?
I have about 70k on the car, but did not replace the reservoir when I changed the fluid out last.
 

·
Registered
Joined
·
105 Posts
Discussion Starter · #9 ·
At high RPM it's pretty normal for some PS fluid mist to come out of the vent hole in the side of the cap. To keep most of the mist inside I cut off the cotton tip from a Q-tip and stuck it in the vent hole. Give it a try, it work well.
Your PS pump is heading for failure, at high RPM's you are loosing pressure which makes it hard to steer.
You could try to open the pump up, flush it out with gas and see if all of the vanes are clean and free to move in the impeller.
The broken mounting tabs are the result of my water cooled alternator seizing and the belt ripping the pump off. I got a used one for ~$175 iirc, new was $400 at the time.
Good to know. I will see what the mechanic says about the belts first, I am hoping they are just slipping at high RPM's. Seems a little early to have pump failure at 70k.
 

·
Registered
Joined
·
5,860 Posts
Hope for the belt, but that is the same belt that drives the alt and waterpump, so if it was slipping you would have probably heard it.
I know of 3 guys that had bad PS pumps, did exactly the same thing as yours, one was replaced under warranty, less than 60K miles.
 

·
Registered
Joined
·
5,860 Posts
It's a breather hole, but it should not spit up fluid.

How many miles on your car? Did you change the reservoir as well when you changed the fluid as it has a built-in non-replaceable filter?
No need to buy a new reservoir. The filter is just a screen at the bottom. Unscrew the plate in the bottom and you will see it.
Flush it out with gas and put the plate back on.
 

·
Registered
Joined
·
4,703 Posts
At high RPM it's pretty normal for some PS fluid mist to come out of the vent hole in the side of the cap. To keep most of the mist inside I cut off the cotton tip from a Q-tip and stuck it in the vent hole. Give it a try, it work well.
Your PS pump is heading for failure, at high RPM's you are loosing pressure which makes it hard to steer.
You could try to open the pump up, flush it out with gas and see if all of the vanes are clean and free to move in the impeller.
The broken mounting tabs are the result of my water cooled alternator seizing and the belt ripping the pump off. I got a used one for ~$175 iirc, new was $400 at the time.
With all due respect, I would refrain from doing this.
As bluebee posted, the main culprit for "overboil" (or what we see) is the failed O-ring. I did not know about this until about 2 years back. The ATF power steering reservoir was always "leaking", and I thought it was "normal", until I found out about that O-ring. I changed it (the original one was deformed and hard, just like the Vanos seals), and no more wet/leaky ATF power steering reservoir since.
Also, every time I change the oil, I pump out as much as I can the power steering ATF and replace with fresh fluid. The fluid looks nice pink in my system since then. Granted, it's not a flush etc, but it beats leaving the old burned fluid in. And pulling out about 1/2 qt twice a year, I believe it helped.
 

·
Seek to understand,^Value
Joined
·
25,199 Posts
Bluebee alert--nice autopsy photo! Thanks.
I added it to the bestlinks so that JimLev's photo can be leveraged further:

- How to fix the wet power steering reservoirs due to poor O-ring design (1) (2) & why you want to fix the power steering hose drip onto the alternator (1) (2) (3) & how to debug PSP power steering pump noise (1) (2) (3) or steering rack noise (1) & a nice power steering pump autopsy photo (1) & how to flush fix cloudy ATF fluid (1) (2) and what PS fluid to use (1) (2) & DIYs to replace power steering hoses (1) (2) (3) (4) (5).

Here is the photo, resized to 640x480 pixels.
 

Attachments

·
Seek to understand,^Value
Joined
·
25,199 Posts
The filter is just a screen at the bottom. Unscrew the plate in the bottom and you will see it
WHAT?

This, if true, is an amazing observation because, to my knowledge, NOBODY has ever mentioned that you 'can' remove the filter in the E39 power steering fluid reservoir.

Since it's unheard of (to date), can someone concur that this is the case?

If so, that's GREAT!

PS: How to you get to the filter from that small opening for the cap at the top of the power steering fluid reservoir?

 

·
Seek to understand,^Value
Joined
·
25,199 Posts
No need to buy a new reservoir. The filter is just a screen at the bottom. Unscrew the plate in the bottom and you will see it.
Flush it out with gas and put the plate back on.
Doing research to see if this is true, Edjack opined it might be so for the OLDER filters, but not for the newer ones (which I have on my 2002 525i).
- E39 (1997 - 2003) > Do we have a picture of the E39 power steering reservoir non-removable bottom filter

EDIT:
However JimLev confirmed you can at least loosen the circular filter to check how clogged it might be:
- E39 (1997 - 2003) > Looks like PS systems are the hot topic today

And, I confirmed the same with my 2002 M54 engine in that thread by suctioning out 8 ounces (250ml) of Dexron VI ATF ...


And then magnetizing a T20 Torx driver to remove the center bolt ...


And then I was able to tilt the screen to check its condition.


Echoing Doru & JimLev, I think these may be reasonable recommendations:

  • Every oil change, suction out about 8 ounces (250 ml) of the power steering fluid and replace with Dexron VI ATF
  • Every five years (or so), when you replace the two lower oil-filter stem o-rings, also remove the T20 Torx bolt holding down the circular screen filter in the bottom of the power steering fluid reservoir and flush with gasoline (off the vehicle!) to clean the screen
  • Likewise, also replace the o-ring in the power steering fluid reservoir cap at the time you replace the two lower o-rings in the oil filter stem
  • And, of course, check/fix leaks in the hose below the power steering reservoir & at the bottom of the power steering pump.
Here's what is in the VERY best of E39 Links to date:
- How to clean the power steering fluid reservoir internal filter (1) & how to replace the cap o-ring (1) (2) & why you want to fix the power steering hose drip onto the alternator (1) (2) (3) & how to debug PSP power steering pump noises (1) (2) (3) or steering rack noises (1) & a nice power steering pump autopsy photo (1) & how to flush fix cloudy ATF fluid (1) (2) and what PS fluid to use (1) (2) & DIYs to replace the power steering hoses (1) (2) (3) (4) (5).
 

·
Registered
Joined
·
105 Posts
Discussion Starter · #17 ·
Great replies and subsequent info. Very helpful. Quick update. Mechanic took a look at it and also figures the pump is going bad. Had serpentine belts replaced about a year ago and is still new. I might try getting the screen out to see if it is all gunked up, as that might cause higher RPM power loss...or at least that is my idea. After looking at the internal pics of the water pump, I have a hard time seing what would go bad inside the unit. Some smart engineer could make a bundle if they could make a bulletproof replacement...

Thanks again everyone.
 

·
Registered
Joined
·
5,860 Posts
With all due respect, I would refrain from doing this.
As bluebee posted, the main culprit for "overboil" (or what we see) is the failed O-ring. I did not know about this until about 2 years back. The ATF power steering reservoir was always "leaking", and I thought it was "normal", until I found out about that O-ring. I changed it (the original one was deformed and hard, just like the Vanos seals), and no more wet/leaky ATF power steering reservoir since.
Also, every time I change the oil, I pump out as much as I can the power steering ATF and replace with fresh fluid. The fluid looks nice pink in my system since then. Granted, it's not a flush etc, but it beats leaving the old burned fluid in. And pulling out about 1/2 qt twice a year, I believe it helped.
Maybe your o-ring was bad and causing PS fluid to leak out. I've still got my 11 year old o-ring in the cap. It's nice and flexible. The Q-tip in the vent hole has reduced the misting problem by at least 90%.
So are you saying your reservoir is completely dry?
What I have found is that if you run your engine in the upper RPM range fluid would mist out of the vent hole.
 

·
Registered
Joined
·
4,703 Posts
Maybe your o-ring was bad and causing PS fluid to leak out. I've still got my 11 year old o-ring in the cap. It's nice and flexible. The Q-tip in the vent hole has reduced the misting problem by at least 90%.
So are you saying your reservoir is completely dry?
What I have found is that if you run your engine in the upper RPM range fluid would mist out of the vent hole.
Before changing the O-ring, the reservoir was wet at all times, literally leaking. When I changed the O-ring, first I placed it wronlgly, because the old one was so cooked and deformed, it looked as if there was no O-ring in place. I thought that I didn't even have the O-ring groove. Once I start using a pick (I thought the groove was filled with some hard deposit), I was certain the O-ring was in place. Hard as the the container itself.
After I placed a new O-ring, the resrvoir was bone dry (I had the right fluid level). It was like that for about a year. Now I start getting a little ATF moisture again, so maybe it's time for a new O-ring.
The reason I said about the weep hole is, there were some guys who plugged it with silicone mind you, and the lines blew due to boiling and high pressure. I know the Q-tip is different, but why risk it?
 
1 - 20 of 29 Posts
Top