Chatter from IP

[Kenneth]

Recently I added my first fuel additive (PS- grey bottle) to the current tank I am finishing up. About last week i noticed a chatter coming from either the tensioner pulley or the IP, wasn't sure. I checked out the tensioner and it was not the problem. Its seems I am hearing a chatter from the IP. The only way I found this was by opening the hood and looking at something else while the engine was idling. I can't hear the chatter from the cab, and can barely hear it with the hood closed (if I listen carefully). I have the stock timing chain installed, which I hear phaser gears can cause this chatter. Is my IP failing or is it the FSD, or something else? Anybody have ideas? I have about 153K miles on the engine right now. The IP was replaced under warranty back in probably 1998 or so.

[93GMCSierra]

At a guess maybe some injectors were dirty an the cleaner is working on them?

[Kenneth]

I replaced my injectors this summer with stock injectors from Heath Diesel. I have only run them for about ~6K miles. But I do notice a tiny leak, I think from the rubber return lines, on the #7 injector. It doesn't drip fuel, but is very slightly moist after driving it 8 miles (from work to home) at 55mph. and the exhaust manifold on that side directly underneath the #7 injector is now spotlessly clean.

[chickenhunterbob]

My guess is that it's just the normal IP chatter you hear, but you just may not have noticed it before.

Mine at least has always had a very audible chatter, which may or may not sound like yours, really difficult to say.

It is pumping fuel to each cylinder at high pressure, now my math may be wacky, anyone feel free to correct, but if a squirt goes to each cylinder every second turn of the crank, then idling at about 600 RPM, that makes about 2400 squirts a minute, or 40 each second.

It may be my imagination, but it seems to me that a little two stroke oil in the tank may reduce the chatter ever so slightly.

[rustyk]

I had a similar issue with my old 6.5L TD - but the noise turned out to be the crankshaft damper pulley hitting the stops. A new damper cured the issue.

[Kenneth]

turned out to be the crankshaft damper pulley hitting the stops.

what do you mean "stops"?

[a5150nut]

what do you mean "stops"?

If you craw under your truck and look up at the front pulley on the crank you will see the stops on the front. When the rubber gives out it will make an awful racket bouncing back and forth.

[rustyk]

Exactly - if the elastomer gives out, the inner section has tabs to prevent the outer section from going its own way.

[Kenneth]

Isn't the pulley bolted to the harmonic dampener? I never looked at the pully but have recently briefly checked out the harmonic dampener. I didn't check all the rubber on the damper but it looked fine. I will definitely do a thorough check of the damper and check to see if the pulley is hitting the stops. Thanks for all the input guys.

[a5150nut]

Isn't the pulley bolted to the harmonic dampener? I never looked at the pully but have recently briefly checked out the harmonic dampener. I didn't check all the rubber on the damper but it looked fine. I will definitely do a thorough check of the damper and check to see if the pulley is hitting the stops. Thanks for all the input guys.

I was corrected a while back. The harmonic balancer is just in front of the oil pan. The front one is the crank pulley. Even if it looks like a harmonic balancer to me...............and Napa called it that too.

[rustyk]

Yeah, there are two thingies involved - one is the pulley, with its own damper, the other is the crankshaft damper, with yet another. My former post relates only to the pulley damper.