Strange Mechanical Whirring Sound When Accelerating

[polycat33]

I have a 2001 1.8T with ~87,000 miles on it.

For a couple months I've been hearing a strange noise when I accelerate. It's making a noise like an electric golf cart? Like, imagine not a completely silent electric car like the new ones, but just the mechanical noises you'd hear out of an old electric golf cart when it goes... that's what I'm hearing. I also kinda think it sounds like a little toy car, the kind you pull backwards to wind and then let go (the sound is similar to the sound when the toy car goes, not when it's being pulled back).

I had a friend who is good with cars listen when I first started hearing it, and he said all he could hear was my turbo, but that maybe I was hearing a belt reacting to the heat of the summer. I just had the timing belt replaced.

The sound is getting more noticable as time goes on. I had the friend listen again, and he said he heard it, but he thought it WAS my turbo, and that's why he didn't hear it before, he didn't know that wasn't what the turbo always sounded like. He said maybe the bearings were going?? But he might not know, or might still not be hearing it as well as I do since I've had the car for ten years, I know exactly what it should sound like.

Does anyone recognize the way I describe the sound and/or have any guesses on what it might be?

I can't be sure it's the turbo, but I'm worried that he thinks that from hearing it because it sounds like it could be expensive. I'm taking it to be looked at by the mechanic tomorrow, but I'd like to be prepared for what I might hear when they call me to tell me the diagnosis.

Any ideas?

[Design]

do you hear it only when driving and accelerating or sitting in neutral/park and revving the engine?

The answer will help narrow down your issue some. A common issue that causes noises like that relates to the secondary air pump. That is a large plastic air blower that is intended to reduce emissions. It is located at the front right of the engine under the intake manifold near the battery.

[IndyTom]

Hmm, could be a million things. Have you checked your Diverter Valve lately? When it is going out it can make some strange noises. If you still have the old style units they used to go out quite frequently. When mine went it sounded more like a sick goose honking. The newer versions last longer and shouldn't be more than about 60 bucks to replace. Or if you are tuned or chipped go with an aftermarket DV like the Forge P007 or the Splitter Valve.

Tom in Indy
00 VW Yellow Beetle 160k miles and still going strong.

[silverliquid1013]

Have you done any work to your sound system? An improper ground will cause it to "whizz" sounding like a low electric sound.

-P

[polycat33]

It's not the secondary air pump, I know what that sounds like as I had issues with it last year, and its brand new. And it's way too subtle to be anything that usually "honks" or "squaks" when it's going out. No work to the sound system, and that would be all the time, not just when accelerating.

The mechanic said it was nothing. At first listen, one guy said it sounded like my turbo was wearing out, then later they thought it was my engine mounts causing the engine to vibrate, but at the end of the day they said the turbo is getting older and thus a little louder but nothing is wrong with it. I'm a bit disappointed with that answer, because I don't understand how "nothing" would start making a sound two months ago that has gotten more noticable with time...... but they're good mechanics and I guess I have to believe them.

[EricSee]

I'm having a similar noise in my 01 TDI Beetle with 122K miles on it.

I had the TB changed a couple months ago and I noticed the sound immediately upon picking it up from the shop. I turned around, had them listen for it, they didn't hear it - said it sounded like a diesel. Took it back a few days later and the tech who had worked on it said he backed off the tension of the TB a little. This seemed to help although it's still present.

I also had my intake manifold cleaned during the same shop visit so I wonder if I'm hearing 'more air'. I was also underwhelmed by the performance increase of cleaning out as much build up as I had in the manifold so I tend to wonder if I'm hearing something that's causing friction and reducing the efficiency of my engine.

[Smileybug]

Were all the rollers replaced when you had the TB done?

[Zann]

My secondary air pump sounds like a jet engine on mine. I kind of like it.

[IndyTom]

Originally Posted by Zann

My secondary air pump sounds like a jet engine on mine. I kind of like it.

Okay. YOu really only should hear that noise for a few seconds on and after start up. If you hear it all the time it's not the SAIP.