Hi!

My '93 SE has just developed a clattering or chattering noise at idle. It is intermittent, too. It'* coming from the passenger side of the engine, so I suppose it'* one of a few things: alternator, water pump, or harmonic balancer (or perhaps something else driven by the serpentine belt. What specific characteristics of each of the above will help eliminate that item? Looking under the hood, it'* difficult to pinpoint the noise, other than to say it seems like one of the above.If I turn on the AC, there is no change in the noise. It'* hard to determine if the noise goes away at higher RPM'*, but I think that it may be less. Hard to tell. BTW, there are no leaks, the oil pressure is 40 @ idle, and up to 80 when driving. Water temp is good and charging is fine. The belt itself looks good. The water pump was changed a few years ago, as was the alternator. The car has 187,000 miles on the clock.

Thanks for the help!
NCC

probably the harmonic balancer my 93 se had the same symptoms and i just had ir replaced a month ago

With the engine OFF, try to roll the alternator pulley in both directions and see if the harmonic balancers outer sleave moves seperatly from the inner hub. You may need a socket and ratchet on the alternator nut to get enough leverage to roll the pulley.

or if the balancer just looks torn like this

chattering? sounds like a worn out rear alternator bearing.

take off your belt and spin all your pulleys. see of any squeak or crack/.chatter....mine was the alt, and the alternators in these cars are very susceptible to bearing damage to over tensioned belts. It happens. check it out.

mine was two things crackling i found out. it was my reman alternator, and it was my tensioner pulley bearing. both were bad, both replaced...crackling all gone.

probably the belt tensioner,watch it while the motor is running and see if it rattles

You could release the tensioner and spin the alt, compressor and other moving parts to listen for the noise.

Just a quick follow-up....it was the water pump! Replaced it...all is at peace in my Bonneville world! Now I am ready for a 16-hour round trip north to the Pittsburgh area to see the folks.

Happy Thanksgiving!

NCC