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What every newbie needs to know when they hear their ALTERNTOR rattling at idle

23K views 45 replies 16 participants last post by  bluebee 
#1 ·
OMG. I hear a rattling sound, at idle, coming from just about where my alternator is!

Ideas and pointers always welcome ... (I will do the search and destroy tomorrow).

Bluebee
 

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#40 ·
As a cross reference, finally, I figured out how to create a video of the noise and posted it to this thread because I don't think it's the alternator anymore.

I did think for a while it was the power steering; but now I'm not so sure since I've replaced it with Dexron II (by mistake); and now twice with Dexron VI (which is compatible with Dexron III).

http://www.youtube.com/watch?v=LQHLKDKt4O0&feature=player_embedded
 
#4 ·
I had same issue and removed the alternator to change the bearings. I was very surprised that out of the car the alternator bearings were very quiet when spun by hand.

I installed it back without changing the bearings, changed the a/c pulleys as evidently they were noisy when spurn by hand (alternator pulley was quiet when spurn by hand).

Now the car's very quiet. What I discovered is that the noise was actually from the a/c pulley which echoed up to the alternator area.

Check all your pulleys by removing the belts and hand spinning them. If they turn easily and make noise, replace them. If they're quiet and spin with a bit of resistance, they're good. I replaced with OEM pulleys from cravier- they're only $36 a piece when purchased over the internet- they have special pricing for internet sales.

Hope this helps.

97 528 sports 145K miles, 05 X5 4.4 sports 62k miles.
 
#5 ·

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#8 ·
It depends on one's tolerance. In my case the pulley was still good as far as spin straight not so much wobbling and play, however it develops a squeal but only during engine cold start, once the secondary pump stops the squeal also stops.
If you ever noticed a new pulley and how its feel, it feels a bit of resistance no so freely spins. If your is wobbling, screeching while hand spinning, or too much play, then it's time to get rid of them.
 
#9 ·
Or, you can carefully prise out the bearing seals on the idler pulleys, wash the old grease out, and repack with hi-temp wheel bearing grease, but not too much.
 
#10 ·
I had a noise EXACTLY as described, but however, in my case, i actually went and replaced alternator bearings, they were a bit dicey and while at it removed leaves and what not from duct..

the problem however, actually turned out to be the Powersteering pump, the dealer i bought my car from had it re-conditioned for me at no charge though...
 
#13 ·
the problem however, actually turned out to be the Powersteering pump
Hmmm ... my powersteering reservoir always has reddish fluid on it and crud, no matter how many times I clean it ... I wonder if it's low on fluid and making noise ... I'll check. thanks for the tip.

Bluebee
 
#11 ·
I had a noise EXACTLY as described, but however, in my case, i actually went and replaced alternator bearings, they were a bit dicey and while at it removed leaves and what not from duct..

the problem however, actually turned out to be the Powersteering pump, the dealer i bought my car from had it re-conditioned for me at no charge though...
 
#12 ·
I just recently had all my pulley's, alternator and water pump replaced by my local indy. They also found that the tensioner pulley was bad and replaced the whole assembly as well. My baby is running like a champ still at 122k miles. Goodluck Bluebee!
 
#15 ·
seriously people as crazy as it sounds, it was the powersteering pump eventually, but sound is a funny thing, it seriously sounded like it was the alternator... remember sound travels along the belts and what not...

we eventually used a mechanics stethoscope to hear for the noise...
 
#17 · (Edited)
Oh oh ... my power steering reservoir is EMPTY!!!! (almost ... almost no oil on the dipstick when the engine was running) .... Ouch!

On a plus note, when I searched for which specific ATF fluid to use, I found that the leak is often on the underside of the pump at the clamp so I'll look there.

 
#18 ·
Bluebee, it can weep from those weak hose clamps, but unlikely that much. If you are down that siginificantly, I would check your PS hoses further down...I have replaced both the upper ones, and lower ones over the years. Where it leaks from the hoses meeting the reservoir is usually quite minor. But if you want to fix it, do what is shown there, now is the time if the reservoir is low, it makes less of a mess (ask me how I know) and get good quality hose clamps, like the Wurth brand. Don't use the crappy ones from your local auto supply house. Go to a German or import supply house, they will have the quality ones.
 
#19 ·
I don't know when I'll get to this (lots of other things in my life at the moment) so I filled up the reservoir with the fluid they sold me in the auto-parts store.

Did I use the right stuff? REDLINE ATF (it says BMW on the back).

 

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#21 · (Edited)
Did I use the wrong PSF (Dexron II not Dexron III)???

I would have gone with Red Line D4.
Did they give me the wrong PSF in my E39 (Dexron II instead of Dexron III)???

Hmmm.... I confess ... I don't know ANYTHING about Power Steering Fluids ...
I looked up Red Line D4 PSF and found there are multiple types of RedLine ATF but, to me, they all seem to do just about the same thing! I'm confused. :(

The Red Line PSF bottle I bought for $12/quart is labeled "Red Line Synthethic Oil Power Steering Fluid" which meets Dexron, Dexron II-D, Dexron II-E, Ford Type-F, Mercon, & M2C138-CJ requirements. Also satisfies API 75W GL-4 Gear Requirements.

Wow, most of that is alphabet soup to me!

Digging a bit, I ran into a nice E46 power steering R&R DIY here and I do see some people use Mobil 1 PSF here but most seem to say almost any ATF fluid will work, as in here.

Oddly, there's nothing about which power steering fluid in the E39 wiki but luckily I found this really good article about changing your Power Steering Fluid in the E39 here which says any ATF that meets Dexron III standards will do for our BMWs.

Oh, oh. The Red Line Power Steering Fluid I bought is apparently only Dexron II. Did I use the wrong PSF ???

 

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#24 · (Edited)

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#25 ·
My 2 cents:
Buy a new reservoir, 3 or 4 new hose clamps and a couple quarts of Mobil 1 ATF. Use an online vendor, because this isn't a huge emergency situation (especially since you used Redline synthetic, rather than Brand X power steering fluid). You don't have to buy a new reservoir, but there is a non-cleanable screen in it, and this is a good opportunity to replace it.

Extract all the old fluid you can; remove the old hose clamps and old reservoir; trim the hose-ends, install the new reservoir with new clamps; refill with the ATF.
Relax. It will be fine. But next time do all the frantic research BEFORE you introduce the new fluids...:)
 
#26 · (Edited)
But next time do all the frantic research BEFORE you introduce the new fluids...:)
I trusted the auto parts guy. I asked "are you sure this is for my BMW". He assured me it was. Obviously, he was wrong; hence, I should not have listened to him.

There's not much here about power steering fluids (PSF); mostly it seems people go with:
- Mobile 1
- Any Dexron III ATF

Based, at least, on these sporadic PSF ATF threads:
What type of ATF to use for PSF?
Dexron II for older BMW PSF
Dexron II or Dexron III for PSF in 3-series

UPDATE: I did call Red Line and spoke to technical support who told me they'd recommend Red Line D4 ATF (which was supposed to meet the Dexron IV proposed specification but GM skipped to a later number but the D4 moniker stuck). When asked about the difference between Dexron II and Dexron III, they said it wasn't a big chemical change ... mostly it was two things, (a) anti-wear chemistry and (b) constant-over-time slipperiness (mostly for use in manual transmissions with low-offset gears).

Strangely, they don't recommend their PSF for manufacturers (such as BMW) who recommend ATF as PSF even though their PSF container (and spec sheet included above) clearly says it meets the Dexron specifications; they told me, quite nicely, that theiir PSF and ATF oils are definitely different.

What I'll do is buy a few quarts of Red Line D4 ATF and do a quickie ad hoc power steering flush DIY :)
 
#28 ·
Yup, ATF only. The outside of the reservoir will get mucky, no matter....the reason is there is a vent in the cap. You can replace the o-ring on the cap, but it will make little difference. I even installed a new reservoir, and then was explained about the vent, and that it is normal. So don't get to "anal" about it. ;)
 
#29 ·
The outside of the reservoir will get mucky, no matter....the reason is there is a vent in the cap.
Yeah ... the only "solution" to the psf muck from the cap venting I saw was on the utube video previously alluded to.

:)
 
#31 · (Edited)
Bad news. It's hard to describe noises but upon subsequent inspection, the noise doesn't seem to be coming from the (now full) steering fluid pump. It's "down there" somewhere.

It's subtle ... but discernible.

I think I need to research those mechanics' stethoscopes ... as I don't own that in my tool repertoire. Depending on cost and usefulness, I generally don't mind purchasing the tools I need ...

Need to dig for recommended debugging tools for hard-to-find noises in the engine bay ...

 

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#33 · (Edited)
I don't have a video camera but I can borrow one. I'll see if I can do that to get a clip of the noise ... but it's subtle ... amongst the ambient engine noise ...
 

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#34 ·
To prevent the power steering cap from leaking your new Dexron III ATF fluid, apparently replacing the O-ring works better than an M5 gym sock.

 

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#41 ·
I bought new belts and twice replaced the power steering fluid with Dexron VI ATF ... and the cold-start squeal seems to be vastly diminished ... but still there.

So I bought a mechanic's stethoscope to see if I can further pinpoint the noise.

I've never used one of these, so, it will be interesting to make sure I don't get wrapped up in it like spaghetti!

 

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#45 ·
Another method (old school) is to use a long-handled screwdriver - set the tip of the screwdriver where you want to listen, and cover the handle end with your thumb, and put you ear on your thumb.

You can hear bearings/bushings going bad or just isolate sounds to a specific area. HTH
 
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