Alternator Whine - Need Ideas

[billr99]

OK, here's the deal. I have a lower pitch whine, not quite a growl I suppose, in the serpentine belt drive system on my '05 XC. Was there when I bought the car a bit over 30K ago and has only gotten slightly worse since but it began to annoy me once I put on a new exhaust that made the car overall much quieter. If I pull the belt, no noise; so at least I have it isolated. For me the logical choice was a bad alternator or possibly an OAP considering the mileage and they were the OE bits. Those were changed out with a rebuild (140A Remy) with a new OAP (INA) with no resulting change in the noise other than a slight change in pitch. Increased load, pulling the load off the alternator makes no difference in the noise. I then moved to the steering pump which I changed out with a used ZF one from Eire. Also changed out the reservoir and the pump feed hose. Same noise; again, with no change with a load like the steering all the way to lock. Using the long screwdriver stethoscope trick, it sounds like all the components, PS pump, alternator , AC compressor are about the same in regard to bearing noise and are really not much different than those on my '05 VR. Serpentine belt (Conti) and roller (INA) have less than 30K kms on them. Noise more or less disappears above 3K revs.

VIDA shows no errors and I'm starting to run out of ideas if I assume that the "new" bits I have put on are the way they are supposed to be. Any suggestions?

Thanks in advance,

Bill

[Astro14]

First candidate for noise in a serpentine belt system is the tensioner pulley. They're cheap. Throw on a new belt and tensioner, and see what you've got.

Just remember this: new parts are not always good.

I've put on new parts and had them be noisy/leaky from day one, so perhaps your rebuilt alternator has the same bad bearings as the old one...

[billr99]

First candidate for noise in a serpentine belt system is the tensioner pulley. They're cheap. Throw on a new belt and tensioner, and see what you've got.

Just remember this: new parts are not always good.

I've put on new parts and had them be noisy/leaky from day one, so perhaps your rebuilt alternator has the same bad bearings as the old one...

Yeah, I know but Conti belt and INA roller? And as I said, it was making this noise before I changed those out. One thing I thought of was that I haven't changed the 0-ring in the high pressure line off the PS pump. I've heard that if you get air in the PS system it can make the vanes in the pump vibrate but I've done a couple of these pumps in past, exactly the same way, with no problems. And I'm not seeing any foaming of the PS fluid as you would expect with an air leak. When I pulled the original alternator I was getting some headlight flickering and was only showing 13.5V at the battery. I've also heard that a single diode can go out and cause a whine due to a phase difference(??); but this Remy rebuild is showing 14.3V which, of course, means nothing if its bearings. Wish there was a way to isolate these components one at a time. But that would be too easy then. Argggghhhh!

Thanks Astro for the suggestion. Much appreciated.

Cheers,

Bill

[Astro14]

As I read your post, I didn't see that you had changed out the belt and tensioner.

You know, I had a bit of a PS whine in the XC many years back, and it turned out to be the PS reservoir, not the pump, even though it was the pump that was whining.

There's a little tube inside the reservoir that directs the fluid from the return line. If that little tube isn't there, then the fluid foams a bit, and the system whines.

In my case, a new reservoir quieted things down by preventing fluid foaming.

Since you've done everything else, put a new Volvo (not aftermarket) reservoir in there and change out your fluid with new CHF-202 (or CHF-11s, I can't remember which). You may find that it's a fluid, not bearing, problem.

[billr99]

As I read your post, I didn't see that you had changed out the belt and tensioner.

You know, I had a bit of a PS whine in the XC many years back, and it turned out to be the PS reservoir, not the pump, even though it was the pump that was whining.

There's a little tube inside the reservoir that directs the fluid from the return line. If that little tube isn't there, then the fluid foams a bit, and the system whines.

In my case, a new reservoir quieted things down by preventing fluid foaming.

Since you've done everything else, put a new Volvo (not aftermarket) reservoir in there and change out your fluid with new CHF-202 (or CHF-11s, I can't remember which). You may find that it's a fluid, not bearing, problem.

Thanks, Astro. Yep, have it all covered. New OEM reservoir, feed hose along with new CHF. See what I mean?

Thanks again for the help,

Bill

[Astro14]

Rats...

Beyond the screwdriver, perhaps it's time for an actual stethoscope?

Rebuilt alternators often have dodgy bearings...depending on who did the rebuild...so, I'm back to that hypothesis... But that's a starting point for a guess.

Perhaps a stethoscope would help you narrow it down. Since the alternator is bolted to the block, noise from it (or the AC compressor) will be transmitted through the engine, and your screwdriver will pick up that same noise as the whole block vibrates. Actual sound should be a bit louder at the point of origin, I would think...

[billr99]

Rats...

Beyond the screwdriver, perhaps it's time for an actual stethoscope?

Rebuilt alternators often have dodgy bearings...depending on who did the rebuild...so, I'm back to that hypothesis... But that's a starting point for a guess.

Perhaps a stethoscope would help you narrow it down. Since the alternator is bolted to the block, noise from it (or the AC compressor) will be transmitted through the engine, and your screwdriver will pick up that same noise as the whole block vibrates. Actual sound should be a bit louder at the point of origin, I would think...

Astro:

Yeah, this is the track I'm heading down. I hate to do it, but tomorrow is a holiday here so I might just start trading bits from my R to the XC to try and eliminate the noisy component. The alternator and PS pump on the R are quiet with 50% less mileage on them so they would be decent enough replacements, then if anything is noisy I can at least not beat my head against a wall and the R will get any new bits

Thanks, Astro, much appreciated.

Cheers,

Bill

[AKAMick]

Just ignore it, and when it gets really loud you will know just what it is.

[billr99]

Just ignore it, and when it gets really loud you will know just what it is.

True enough. Problem is that we drive through some relatively desolate country once a week with this car and I'd hate to have the hassle of a breakdown out there. I've had an alternator go out in a P2 and you don't get very far. Plus if its the PS pump, these things are a real bitch to steer without assist. Anyway, I'll be swapping known good bits into the problem tomorrow so we'll try narrowing this down a bit then.

Thanks,

Bill

[vtl]

Rebuilt alternators often have dodgy bearings...depending on who did the rebuild...so, I'm back to that hypothesis... But that's a starting point for a guess.

This is what I think too. A pair of real good bearings cost me about $100 alone, and I had to ship them from random ebay sellers in Europe. Didn't have luck with easy to source bearings, they are either louder than the old ones, or die in 6 months. I pulled the old bearings and was searching for the new bearings with the same index, which turned out to be not so easy. Before pressing in the bearings, I've opened them up and added a bit more Polyrex EM grease. The rebuild cost me over $200 just in parts (without diodes), but the alternator is quite. New one in wife's new XC60 is much louder.