Engine Clatter

Tiny
80 GRIT
  • MEMBER
  • 2009 VOLKSWAGEN ROUTAN
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 176,000 MILES
I'm hoping someone can help. Has a chatter. At idle only, if you accelerate it stops. It only does it when the motor is warm and at operating temperature. The sound is worse when you turn the wheels lock to lock. If the ac is off, it rarely makes it, but when the ac is on, it is loud. It sounds loudest at cylinders 4 and 6 and only on the top of the motor. It sounded originally as if it was coming from the power steering pump. I replaced it but it didn't help. The sound started after I replaced the upper and lower oil pan gaskets. Everything looked good when I changed them. I have also replaced all of the engine and transmission mounts. I have also replaced the tensioner, idler pulley, and belt. Thinking possibly a lifter. It runs smooth, no loss of power, no other issues. Has been going on for about 2 months now. Any ideas?
Sunday, August 9th, 2020 AT 6:24 PM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This could be a lifter as you are suspecting. However, the 3.8L was known to have issues with the A/C compressor starting to lock up. Remove the belt and run the engine for a few minutes to see if it does it. If it does it with the belt off then we know it is inside the engine. If it does not then that make a little more sense as to why it does it with the A/C on.

If this dose not make a difference then we need to monitor the fuel trims with a scan tool while it is running rough. Next we need to check for a floating valve. Intake valves need to be checked with a vacuum gauge. Exhaust valves can be checked by holding a dollar bill over the tailpipe. If it feels like it is being sucked in the you have an exhaust valve hanging open.

Let me know with all this info and we can go from there. Thanks
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Sunday, August 9th, 2020 AT 6:37 PM
Tiny
80 GRIT
  • MEMBER
  • 2 POSTS
Thank you. I forgot to mention. I did run it with the belt off. It still made the sound. It was slight and faint, but still there. A friend just suggested a catalytic converter could be bad. I will check the exhaust pressure. Again, thanks. I'll let you know what I find out.
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Sunday, August 9th, 2020 AT 7:25 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. Sounds good. If you don't turn anything up with that then you can use a mechanic stethoscope to pinpoint the noise. Normally if it is a lifter you can pick it up on one side louder then the other.

Keep us posted with what you find. Thanks
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Monday, August 10th, 2020 AT 7:07 PM

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