What's Making This Noise?

[PoloDave]

Diesels, I love them.

+1, I'm hooked since I drove a chipped 330D with 550nm. Don't care for hp, buckets of torque ftw.

[pontiff]

Hi all,
The Polo has just started to make this noise recently where below 1,200 rpm under load it will emit a loud knocking noise from the engine. At all other revs, and during idle, it sounds perfectly normal. I was wondering if anyone here could identify exactly what in the engine is making the noise.
Video: VW Volkswagen Polo 6R TDI 2011 Strange Engine Noise - YouTube

Thanks

Alex.

alex... im in officer and have a vag-com cable so if you wanted to bring the car out we could plug it in and see what there is to see.

it does sound like engine knocking to me also.. does it do it if you hold that rpm at which it occurs while driving but while stationary?

i had the AC / fuel hose rattle on me yesterday only at idle. as soon as i moved it to the other clip it was fine, but it does wobble around the place....

[alexaescht]

Sounds like a rooted injector ( who would have thought, a vw diesel injector dying!) or a loss of compression. My hilux sounded very similar when I lost compression in cylinder 3.... I hope for your sisters sake, it's just an injector and more likely than not, that's what it will be. Stand begin the car and see if there is more soot than usual upon acceleration. If there is, that's a pretty sure bet its a rooted injector that is just dribbling fuel into the cylinder rather than atomizing it.

Diesels, I love them. Generally if you have a miss, there's only 2 things that cause it. Fuel delivery (work back from the injectors) or timing when an engine hasn't been times correctly

It has a DPF Gav, so any soot is filtered out of the exhaust stream before it reaches the tip. It's still driving fine above those rpm's and there are no warning lights so me thinks we'll wait until next service. Thanks though

alex... im in officer and have a vag-com cable so if you wanted to bring the car out we could plug it in and see what there is to see.

it does sound like engine knocking to me also.. does it do it if you hold that rpm at which it occurs while driving but while stationary?

i had the AC / fuel hose rattle on me yesterday only at idle. as soon as i moved it to the other clip it was fine, but it does wobble around the place....

It only makes the noise under load (I.e accelerating hard or going up a hill) not when stationary. Once again, I highly doubt it's a cable or clip thing because it's just too loud to be.
Thanks for the VCDS offer, I'll think about it but my 'position' in my family makes things difficult

[pontiff]

It has a DPF Gav, so any soot is filtered out of the exhaust stream before it reaches the tip. It's still driving fine above those rpm's and there are no warning lights so me thinks we'll wait until next service. Thanks though



It only makes the noise under load (I.e accelerating hard or going up a hill) not when stationary. Once again, I highly doubt it's a cable or clip thing because it's just too loud to be.
Thanks for the VCDS offer, I'll think about it but my 'position' in my family makes things difficult

your position? the women tell you what to do eh

Car is under warranty and you live in harkers, just drive it into berwick VW and get one of them to go for a drive with you. Think of it this way, you are doing them a favour as by leaving it, may be causing more damage that will just be a warranty job for them anyway, where as if you get it looked at sooner it may be able to be headed off at the pass.

[gavs]

It has a DPF Gav, so any soot is filtered out of the exhaust stream before it reaches the tip. It's still driving fine above those rpm's and there are no warning lights so me thinks we'll wait until next service. Thanks though

So do half the diesels in our fleet and they still blow soot/smoke. All diesels do regardless of the marketing spin. I was following a brand spankers ML class last night and that was puffing out smoke like puffing billy, but you can only see it at night with headlights on. If the injector is performing badly enough no dpf will stop it smoking. I spent a lot of time stripping down and putting hilux diesels back together. Granted modern injection is more complex (read, dangerous. I saw the resultant photos of a toyota tech crossing a common rail injection system the wrong way. He is now known as 'lefty') but it is fundamentally the same. High pressure fuel delivered by a spring loaded injector into a cylinder that due to the high level of compression ignites the fuel. In fact, I'd hazard a guess to say that with the software now loaded into these modern diesels they are easier than ever to work on because there are less things to line up and time correctly and adjust. It's all done with the click of a mouse instead.
I digress!

Just try it and see. And don't let your parents and sister wait, get it looked at immediately, especially if its an easily reproducible problem. There are known faults with vw diesel injectors and the dealership won't tell you that until you ask what the sticker is on the inside of the drivers door.

[alexaescht]

So do half the diesels in our fleet and they still blow soot/smoke. All diesels do regardless of the marketing spin. I was following a brand spankers ML class last night and that was puffing out smoke like puffing billy, but you can only see it at night with headlights on. If the injector is performing badly enough no dpf will stop it smoking. I spent a lot of time stripping down and putting hilux diesels back together. Granted modern injection is more complex (read, dangerous. I saw the resultant photos of a toyota tech crossing a common rail injection system the wrong way. He is now known as 'lefty') but it is fundamentally the same. High pressure fuel delivered by a spring loaded injector into a cylinder that due to the high level of compression ignites the fuel. In fact, I'd hazard a guess to say that with the software now loaded into these modern diesels they are easier than ever to work on because there are less things to line up and time correctly and adjust. It's all done with the click of a mouse instead.
I digress!

Just try it and see. And don't let your parents and sister wait, get it looked at immediately, especially if its an easily reproducible problem. There are known faults with vw diesel injectors and the dealership won't tell you that until you ask what the sticker is on the inside of the drivers door.

Ok well I've never noticed any smoke come out the back, but I haven't ever really looked...
I'll push them as hard as I can for them to get it looked at, but if they need to keep it for more than a day then problems arise – my sister is under 25 so the stealership won't let her use a loan car.
We will see...

Thanks.

[nomadx38]

I'm 20 and they let me use the loan cars. You just have to make them aware that you are a P plater and they up the insurance excess

[Barracuda]

I'm 19 and on my Green P's and the dealers never have a problem with loaning me a car. In fact, the last loan car I had, they gave me a brand new 2012 118TSI Golf with 80ish kilometers on the clock! Haha

Nomad is right though, just let them know if a P Plater will be driving and they make the necessary adjustments to the excess.

[alexaescht]

I'm 20 and they let me use the loan cars. You just have to make them aware that you are a P plater and they up the insurance excess

I'm 19 and on my Green P's and the dealers never have a problem with loaning me a car. In fact, the last loan car I had, they gave me a brand new 2012 118TSI Golf with 80ish kilometers on the clock! Haha

Nomad is right though, just let them know if a P Plater will be driving and they make the necessary adjustments to the excess.

Ok will ask again. Thanks.

[Hail22]

How did you go with asking the dealer about the your noise concerns?