Strange metallic dry bearing / induction type noise

[JonP01]

I was driving along this morning and suddenly noticed a strange noise coming from the front of the car or engine bay. It is like what I imagine a dry bearing might sound like, but it seemed to be linked to the induction noise. In other words, my induction noise has suddenly become metallic sounding as if something metallic is loose or has no lubrication. At first I thought it was the air conditioner but after turning it off the car was still doing it 20 minutes later. The sound is almost inaudible with a closed throttle, loudest at, say 50 kmh in 4th gear under light to medium throttle (so loudest at, say, 50 Kmh, 4th gear climbing a hill) and does not appear change pitch at all regardless or gear, road speed or throttle opening.

It has never made this noise before in the 18 months I've owned it and it did seem to start quite suddenly in that I noticed it when turning into a road near home.

It's booked in for next Wednesday for VW to look at but I just wanted to know if anyone had any ideas or experience with this problem. I just want to be a bit better informed if they try the "it's normal for the model" tactic on me.

My car is the MY13 77TSI manual.

Thanks

[nomadx38]

I was driving along this morning and suddenly noticed a strange noise coming from the front of the car or engine bay. It is like what I imagine a dry bearing might sound like, but it seemed to be linked to the induction noise. In other words, my induction noise has suddenly become metallic sounding as if something metallic is loose or has no lubrication. At first I thought it was the air conditioner but after turning it off the car was still doing it 20 minutes later. The sound is almost inaudible with a closed throttle, loudest at, say 50 kmh in 4th gear under light to medium throttle (so loudest at, say, 50 Kmh, 4th gear climbing a hill) and does not appear change pitch at all regardless or gear, road speed or throttle opening.

It has never made this noise before in the 18 months I've owned it and it did seem to start quite suddenly in that I noticed it when turning into a road near home.

It's booked in for next Wednesday for VW to look at but I just wanted to know if anyone had any ideas or experience with this problem. I just want to be a bit better informed if they try the "it's normal for the model" tactic on me.

My car is the MY13 77TSI manual.

Thanks

Turbo wastegate actuator mate. Even after the 24v9 (or 29v4 I forget) service campaign it will still do it, the only thing the campaign will fix is that the rattle will disappear when you quickly rev it. All they do is put a shim on the actuator to put a bit more tention on it + software update for the new values.

You would think they would have fixed this from the production line since the campaign was out early 2012.

If you put your car in 6th and drive up a slight hill below 1200rpm and get the rattle then that's the one I'm talking about. Against brick walls / tunnels with front windows down its really obvious.

[JonP01]

Thanks for the reply. It seems odd that given this is such a common problem, my car never had it until yesterday (around 18 months and 9,000 kms). I went for a test drive yesterday afternoon and it is loudest at around 40 - 55 kmh in 4th gear when gently accelerating up an incline with no more than, say, 30% throttle. Higher road speeds, higher throttle settings or higher engine revs will not make it any louder than the scenario I just described. It also does not happen with a cold engine. The engine both needs to be fully warmed up and if the engine has been stopped, it takes about 800 odd metres of driving before I start to hear it again. I'm wondering if it could actually be this infamous fuel line problem.

The thing is having read a lot of descriptions of this wastegate rattle, I don't think the terms anyone else has used I would have used myself -and the few YouTube videos with decent sound don't seem to match either. Though I guess the fact that it gets louder the higher the gear (and is all but missing in 1st gear) does tend to point to this wastegate issue. Trying to come up with a better description it is like the induction sound has changed so as to emulate a vey loud coffee percolator with a very metallic sort of sound. But the sound is more a mild metallic grating sound than a rattle. Were it not for the fact that it does not ever seem to change in pitch, my money would have it as being a stuffed wheel bearing. In any event, I'm just hoping it isn't something serious and that I don't get fobbed off by VW.

I just have another question. Can someone out there possibly find out what service campaigns might be outstanding on my car if I supply VIN via a PM? I know the dealer can / should look this up but I would like to know myself if there is anything outstanding before I turn up there. The car has been serviced by an independent and has never seen a dealership since the first 1,500 km inspection 16 months ago. I did find a link to VW (US?) where you could input the VIN but it seems to be permanently disabled, probably because it sees my IP is not US based (and it might not have the correct info anyway).

[Hillbilly]

They don't have Polos in the USA Or at least I never saw any and they don't list on parts pages there.

[JonP01]

I've made a sound recording of the noise. Here I am gently opening and closing the throttle. You will hear the sound get louder as the throttle opens and it get softer when I close the throttle.

Download polo_noise_test.mp3 from Sendspace.com - send big files the easy way

[JonP01]

With a bit of luck I think I might have solved the problem! Was checking under the bonnet tonight looking for anything that might be lose, etc, then noticed the insulation on the firewall was completely lose! The retaining washers were letting the insulation simply "float" on the reatining self tappers and it wasn't sealing against the firewall at all. Even worse, one clip was completely missing leaving a good chunk of the insulation completely free of the firewall. I tightened up the clips that were still there then temporarily put a rubber bungy and washer over the screw where one is missing. Then went on test drive. All funny noises gone! I was actually wondering why I had been hearing more noise than I used to from the engine bay area but put it down to my imagination. But I wasn't imagining it. I'm not sure how they got that way or how one completely came off, but maybe it was somehow related to the windscreen replacement I had a couple of months back.

btw, in the recording above, I deliberately enhanced the noise to make it easier for "diagnostic" purposes. It was far quieter than that in real life and more "burbly" rather than outright metallic as you hear in the recording. But there wasn't going to be any point given them a recording where you could hardly hear anything. whatever the case, this actually would have been an instance of "normal for the model".

You guys might just want to check the insulation on your firewalls just in case they are not fastening it properly at the factory.

Mind you, when doing diagnostics myself for this sound, I think I might have come across a dodgy secondary air injector pump. I will record it at the next cold start and take the recording down to the local dealer. Should not sound anywhere near that jet-engine whiny on a cold start.