2021 Polo Engine clatter

[Dan0400]

Hi everyone,

New here, looked on the forum for other topics and such but couldn't find anything relevant.
Trying to diagnose a weird ( plastic ) clatter on a polo i bought 2 weeks ago. Unfortunately i couldn't hear the noise when i bought the car, so now i feel a bit dissapointed in myself. However, the sound doesn't seem to be something majorly bad, but still enough to be on my mind all the time as its not normal.
Here's the video : https://youtube.com/shorts/AXvS9eodCnw

Some more details:

• Engine is an EA211 Evo 1 ( 95hp, VNT Turbo - TSI )

• 75k miles

• Manual transmission

• Engine sounds normal at cold start

• Noise becomes apparent when the engine warms up a bit ( or something else warms up with it, plastics, vacuum lines, idk )

• It's RPM dependant

• Does not sound like something metallic

• Seems to resonate through the intake manifold/charge pipes

• Pressing the brake pedal hard, or disengaging it, makes the sound go away for 10-15 seconds, then it comes back

• I've done over 600 miles since i bought it and the sound has not changed ( includes about 300 miles of highway )

• Did an oil service, no change. Started the engine with the new oil and the sound came back in like 60 seconds

• Engine pulls good, linear, no weird noises under load or WOT

• No weird shaking under load, no apparent issues with the Clutch or flywheel

• No weird jerks or shakes at idle ( thinking of valves here ), no misfires when cold started or when warm

• No codes shown, besides the Start-Stop that's been manually de-activated

What I've checked ( or others )

• Car has been at 2 different mechanics, one of them listened with a stethoscope and could not pinpoint the sound, he checked the top-end ( cams ), the HPFP and the timing belt cover

• I've opened the oil cap with the engine running and nothing changed, I don't feel any major suction in the cap either

• Slightly removed the oil dipstick, no change

• Removed the auxiliary belt, started engine, no change

It is definitely not normal, and i don't want to just live with it. I'm also slightly afraid of it not being something more serious. I kind of chilled out when i noticed that engaging or disengaging the brake pedal makes the sound go away, kind of pointed me in the vacuum direction, but i'm not sure if this is a side-effect. Let me know your thoughts

[ho8882000]

I have the 1.6 MPi (Non turbo version of the EA211 Engine) in my 2019 Polo with manual transmission, it made some abnormal noise during idle when the engine is at its normal operating temperature (90C). To cut the story short, it was the hard plastic pipe of the N80 EVAP Purge Valve have cracks on it and the leaks causing the abnormal noise.

An easy way to check is:
1) Make sure engine is at normal operating temperature (90C).
2) Let it idle and wait for the abnormal noise to happen.
3) While the engine is running at idle and making that abnormal noise, unplug the electrical connector on the N80 EVAP Purge Valve. If the abnormal noise disappear, then cracks on the hard plastic pipe will be the root cause of the abnormal noise.

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[ho8882000]

I replaced it with aftermarket rubber fuel hose, it is much cheaper than the original VW hard plastic pipe which will crack again after a few years.

This is the cracked hard plastic pipe of the N80 EVAP Purge Valve removed from my Polo:

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[ho8882000]

On the other hand if your 1.0 TSi engine have brake vacuum line, please also check your Polo's brake vacuum line's hard plastic pipe for crack as well.

Since you mentioned "Pressing the brake pedal hard, or disengaging it, makes the sound go away for 10-15 seconds, then it comes back".

[ho8882000]

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[Dan0400]

Hi, Thank you for your reply!!

I've had time to check this out, and its not the purge valve. I can feel it ticking, but it's on a different frequency than the sound, it ticks slower.

Also, the plastic pipe is wrapped in heat foil for me ( the one behind the engine ), so it's not broken.

The car still drives like that, i can't say i feel a noticeable change in the noise it makes. It sounds the same as it did my original video, but the noise did seems to resonate in the intake plenum, the big box that also has the charge cooler in it.