Noise in front of 3.8L engine w/ 130K mi ...

All,
We've got a 2005 Dodge Grand Caravan with the 3.8 L engine and 130K
miles. When the engine is at normal operating temperature and idling
under a load (the transmission in D and holding van with brake), there
is an intermittent knock/clatter from the front of the engine (sound
like spark knock). Here what I know:

1) it is not a collapsed lifter; the noise is too low, not as sharp as
the ticking of a lifter and is irregular;
2) it seems to be tied to engine speed. While the noise is irregular,
the frequency increases with RPM;
3) when the transmission is disengaged (shifted to P), the noise is
significantly reduced.

Sounds like it is coming from the timing chain / water pump area. I
am a pretty fair mechanic, but before I tear into this, I'd like to
know where the engine is predisposed to certain issues other mechanics
may have seen, with these symptoms and miles. What are your thoughts?

Thanks in advance,
Chris

 

it might be a bearing on one of the pulleys. I donot know why it makes
when it when you are on load,

Also it might be something loose that vibrates when it is on load. the
sound travels and resonantes at a random place.

If it does not go bad, keep using as is. Othervise you are shooting in
dark and it might be very ugly.