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    Thread: Passat 2.8 V6 30V - Engine Noise "Rattle"

    1. 02-18-2008 05:35 PM #1

      My '99 V6 30V w/ 59K miles has started to make a strange noise.

      It is quiet until warmed up, then the sound starts. I suspect something emmisions-wise is activating after warmup.

      It sounds like a rattle, or gulping, abouty 2-3 hz, fluid or air I can't decide. It does increase w/ throttle, but not proportionally - it just speeds up a bit. volume is pretty steady, it doesn't get louder.
      So, I don't think it's in the valve train. Perhaps intake? Is there something that might be "flapping" in there, some sort of proportioning valve? (mine is NOT a VR6, it's the 30-valve Audi engine).

      I think it's "sucking" realted, if that makes sense. I checked the PCV pipes, a little gunky but clear; no cracks found. The combi-valve is working, tho there was a vacuum leak in its line which has been fixed. The secondary air-injector motor runs normally - the sounds isn't realted to it running.

      I've looked all over, it is not something vibrating nearby in the engine compartment.

      The engine runs fine otherwise, but I suspect something is on the way out.

      I don't think it's water pump either, since the noise isn't tied to engine rpm. But hell, I just don't know, that's why I'm, asking!

      TIA!


    2. 02-18-2008 05:56 PM #2
      When I first saw post title I expected it would be "cam adjuster" chain rattle..there are two hydraulic adjusters (one on front of left bank and one on rear of right bank) that use a roller chain to tweak the intake cam timing if the adjuster wears/chain gets slack an rattles..most often when cold starting B4 oil pressure tightens things up. If the "rattle" is comin from the intake manifold area..there is a vaccum acuated "tuning flap" that changes intake runner configuration..if the linkage for that is broken/off then you could hear noise from that?
      96 Golf...Gone...But not forgotten..Great ride!
      2000 Passat GLX...Gone...But not forgotten either..have scars on my knuckles from all the "wrenching" to keep it on the road!
      2008 Rabbit S, VWsport springs/OEM shocks, GTI brakes all around, GTI rear swaybar...best balanced car I've had in a while!

    3. 02-18-2008 06:08 PM #3
      I had a similiar experience with my BMW that turned out to be a broken bracket in the muffler system up near the transmission. It too only occurred after the engine warmed up, thus causing the gap in the two broken pieces. The rattle then came at certain rpm's when the engine reved and shifted a little to cause the two to rattle against each other. It sounded bad, but was an easy fix once I figured it out.

    4. 02-25-2008 12:08 AM #4
      Quote, originally posted by paul_cat »


      It sounds like a rattle, or gulping, abouty 2-3 hz, fluid or air I can't decide. It does increase w/ throttle, but not proportionally - it just speeds up a bit. volume is pretty steady, it doesn't get louder.


      if by gulping you mean a fluid type sound like gurgaling. i would make sure your heater core is bleed.

    5. 02-28-2008 01:11 PM #5
      following up: I have not found the cause yet, it is not in the intake runner, and the coolant levels are fine and pumping into the reservoir as normal.

      I definitely think its some thing emmisions-system related, the sound does not occur when cold, it only "comes on" after a couple of miles of warm up. Something vacuum operated is activating when warmed up.

      Could the combi valve be making this noise, if it's opened just slightly?

      Thanks for the help, all.

      -=PSH=-


    6. 02-28-2008 01:41 PM #6
      could it be an exhaust leak? they often sound like a rattle.

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