Strange engine sound 328

Car has previously run great for a few thousand mi, last driven 5 days ago. Just started it now and I hear this new rhythmic tapping/knocking sound coming from the right side of the engine, though I can't pin it down. Could not tell if its cadence increases w.RPM since I don't have another body to gas it. Shut it off, restarted and it persists. Took a couple vids, the 2nd of which you can hear it better w.the bonnet closed. In the 1st, it's more audible twds the end of the clip. It sounds a bit adulterated through the crappy video as it really sounds like tapping a wooden spoon on the bottom of an empty coffee can, w.a slightly more metallic sound than wood would produce. Make any sense?!

Sound ominous? Like I shouldn't drive it?

http://www.youtube.com/watch?v=ehbOost_bno

http://www.youtube.com/watch?v=ay9P_j7i0b4

 

Well, I started it a 3rd time after posting and sound was not present. Gently drove it around the block stopping a few times to listen and nothing. Went for a longer drive to dinner and still nothing - which is good. I hadn't heard it before so was a little concerned.

 

I watched your videos...I think your ACC belts are making the noise. get some belt dressing from Pep boys, take off the air box and spray some dressing on the EXPOSED belts the one that is on the water pump. Most likely you should change the belts soon, but if its coming and going there is no rush. Mine do it when it gets cold out, or the car has set for a while... several weeks.

It can happen all of a sudden, and sounds terrible... luckly its not catastrophic...

cheers!

Tom

 

I can't quite tell from your video's. When was the last time you changed your accesory drive belt? Usually there is a metallic sounding noise when the belt gets older and it is cold. As the belt warms up this noise goes away. The belt apparently has some sort of plastic ribbon in it that gets old and less flexible over time. As the car warms us this platic ribbon warms up, becomes more pliable and stops making the noise. No biggie, but if these are symptomatic of what you have, you should change that belt.

Alberto

 

Thanks fellas, sounds like what you're describing esp as it went away as it warmed. Coming soon: a thread from me asking how to change the belt

 

You can easily rev the engine from under the hood. Just rotate the throttle where it enters the plenum. Look for the end of the throttle cable and rotate the part just as the cable would do.

 

Uh, err, yeah I knew that. Can't believe I didn't think to do that, esp since I have lubed that more than once in the last few months

Thx

 

Not hard, just time consuming. If you are going to replace the belt, check to see if you need to do your water pump... search for a water pump replacement thread... that should give you the proceedure.... use the belt dressing for now, and most likely it will go away.

 

Just curious if your ac is on or off when noise is present. A compressor can make some awful noises but I agree with other posters its most likley loose-worn belts. You can check pretty easily. Jack up rear of car, remove wheel and remove wheel well liner and all three belts are right there.

 

One test you could do is to remove the belts, start engine and see if noise disappears. Then replace them one at a time to see which one is the culprit. Needless to say, I'm only talking fan belts here.

 

My 1980 308 has almost the exact same sound but not as loud. Seems to best be heard standing at 45 degree angle from the water pump and about 5 feet from the car. I noticed you had the camera at this angle.