Volkswagen Passat (2001 - 2005) - 03 1.9 noise at 1500rpm

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Fri 18 Dec 2009 20:18
03 1.9 noise at 1500rpm - JustMike
Hello fellow dirty fingernail men,

My daughter's 100bhp diesel Passat has done 113k miles and been trouble free. I heard a different engine noise last week and suspected the alternator bearings or the PAS pump. Her garage confirmed it was the clutch drive on the front of the alternator and replaced it. The old one could not be turned by hand after being removed. Result happiness ??- not quite.

Just been on a 400 mile motorway run in it and it performed well, as usual but at exactly 1500 rpm there is now a booming noise from the engine bay.Not alarmingly loud but quite noticeable and just at 1500 rpm - not 1400 or 1600. Change down or increase revs and it disappears totally. I dont think it was there before the alternator was changed.

Its almost a "harmonic balance " thing - bit like when you can get pipe hammer in your house copper central heating pipes at certain water pressure/flows.

She's not even aware of it (and I wont tell her) and I suppose it may disappear in time when a drive belt or something settles down but I would like to further my education if anybody has any ideas.

Thanks for listening/any advice and a Happy Christmas


Mike
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Fri 18 Dec 2009 22:15
03 1.9 noise at 1500rpm - craig-pd130
First thing I'd check is the air inlet trunking to the airbox, this is just a push fit onto the airbox intake and can pop off. When it does you get a ridiculously loud, flatulent resonance at lowish revs because the hollow tube vibrates against the hollow airbox.

My MY03 Passat 130 did this, a couple of blobs of blu-tak fixed it.
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Tue 3 Dec 2013 19:01
03 1.9 noise at 1500rpm - Passat_TDi_Sport_53

I had the same problem on 53 Passat tdi. I used a cable tie to hold the duct in place (looped the cable tie through the headlight bracket). I also found wear on the wiring loom where it had been rubbing on the air duct. Used self amalgamating rubber tape / electical tape to protect the loom from further damage.

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