Power Steering Cap O-Ring

helmet75 · Jun 26, 2014

There was a post regarding a better o-ring for the power steering cap and although it was a few years ago, I was wondering if anyone had a spare ring for sale.
I can't justify going to Baron BMW here in KC and I have checked many stores to find the specific size (M2.5x42 75A Shore) outlined in those posts and had no luck. I could only find M3x42 50A and I know it will not stand up to the rigors of the engine compartment heat nor the fluid eating it.
If someone has one to part with, please let me know and we can work out paypal options for payment

Many thanks in advance.

edjack · Jun 26, 2014

So, the dealer could not supply the correct part? I find that difficult to believe.

helmet75 · Jun 26, 2014

I never said they couldn't supply the part, but it is nearly 40 miles one way for me.
I can't justify the fuel I would use for it.

jygesq · Jun 26, 2014

Can't dealer mail part in simple envelope?

it weighs nothing, 49 cent postage should do it, my dealer does mail,all the time instead of my car club discount.

540 M-Sport · Jun 26, 2014

A generous fellow member here hooked me up from that thread and supplied me with the "upgrade" o-ring. I can tell you it didn't help. It is a bit thicker in all dimensions...so much so that you cannot screw the cover down flush...it will sit "proud" about 1mm or so above. It was sealed tight...but I think it still leaks our from the vent...and that is where the majority of the problem lies. And you don't dare plug the vent and cause some other issue. I was changing my oil recently and noticed the top was oily/dirty as usual and I gave it a bit of cleaning.

JimLev · Jun 26, 2014

The head of a Q-tip pushed into the vent hole will prevent almost all of the mist from escaping while still allowing venting.
I've had one in the vent hole for the last 10+ years.

Jase007 · Jun 26, 2014

It was sealed tight...but I think it still leaks our from the vent...and that is where the majority of the problem lies.

I replaced mine and it still leaked.

Like these guys, I placed some wadded up (but breathable) scotch brite into the vent hole in the cap.

Works OK but still occasionally leaks through.

Cheers.

bluebee · Jun 26, 2014

Contrary to the experiences listed above, I didn't plug the hole but did replace the o-ring, which worked just fine, for about 2 or 3 years.

Now I need to buy a new generic o-ring:
- How to clean the power steering fluid reservoir internal filter (1) (2) & how to replace the cap o-ring (1) (2)

I think it's not dependent upon years so much as how many times you screw the cap down ...

See also:
- Power steering fluid (1) (2) & power steering fluid flush DIYs (1) (2) (3) (4) & volumes (1) & how to clean the power steering fluid reservoir internal filter (1) (2) & 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 cloudy ATF fluid (1) (2) (3) (4) (5) & what PS fluid to use (1) (2-pdf) (3-volume) & what volume is needed to buy (1) & DIYs to replace the power steering hoses (1) (2) (3) (4) (5) & how to debug common BMW power steering issues (1) and noises (1) (2) (3) or steering rack noises (1)
& does an ATF leak from power steering hoses onto the alternator really cause the bearings to fail (1)

helmet75 · Jun 26, 2014

wow, thank you guys! I'll try the q-tip trick when I replace the o-ring.
Luckily it's not my car. I ran in to a gentleman at the gas station a few weeks ago and he had fluid all over his reservoir and airbox.
I offered to help with his codes and the pesky leaks he has.
he drives an 02 525i identical to mine. Same color paint, interior, wheels and even the tint on the windows.
He's had his for about 4 years I think and he said the leak started not long after he bought it but never knew the cause.

bluebee · Jun 26, 2014

helmet75 said:
I'll try the q-tip trick when I replace the o-ring.

Personally, I don't subscribe to the Q-Tip theory, but, if it works, that's all that matters.

BTW, here are a list of parts to stock up on ...
- Complete list of E39 stuff (parts, tools, fluids) to stock for handy eventual use

helmet75 · Jun 26, 2014

I can see a few of those I need to keep in a safe place

JimLev · Jun 27, 2014

If you rev the engine to red line that will cause the PS fluid mist to come out of the vent hole much faster than driving the car like a granny.
Also having too much fluid in the resevoir will increase the misting out of the vent hole.
Might not be an issue for the I6 crowd.

bluebee · Jun 27, 2014

JimLev said:
... driving the car like a granny.... having too much fluid in the resevoir ...Might not be an issue for the I6 crowd.

I (a) drive like a granny, and (b) don't overfill the reservoir, and (c) have the I6.

For me, the o-ring works, but only for a couple of years.

cn90 said:
Just gather all the stuff you need (O-rings etc.) to save shipping cost.

Typing /free shipping f3 in the bestlinks nets these parts lists:
- Glovebox printouts for emergency use (1) and how to save $ money to qualify for free shipping on UPS/DHL/USPS/FedEx by stocking O-rings & gaskets & bulbs & vacuum hoses & fuses & wiper blade inserts & belts & bearings & oil filters & cabin air filters & engine air filters & fluids in your garage whenever ordering from the recommended parts suppliers.

cn90 · Jun 27, 2014

@helmet,

I don't know how good Barron BMW in KC is, but I use a BMW/Mercedes dealer in Lincoln, Nebraska.
It is close to you, so you should get your stuff within 2-3 days.
Pricing is very good and shipping is low.

Just gather all the stuff you need (O-rings etc.) to save shipping cost. They are very good people to deal with.

http://www.huskerparts.com/partlocator/index.cfm?siteid=215771

Power Steering Cap O-Ring

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