I have a 97 SSEi with 123,000 miles. I have stumped tech help at ZZP with this one. I started having a grinding noise from the engine about a month ago, it only happened when under heavy acceleration and especially when going uphill. I checked sc oil and added about 2.5 oz.. The noise is progressively getting worse. It only makes this noise when in gear and under acceleration (revving in park=no noise). I disconnected the sc belt and took it for a drive, no noise even when under heavy acceleration. I also had new plugs and wires installed. Anyone got any ideas.

First two cheap things to try, even though I don't like shotgunning (but this is a tough one to troubleshoot) is to simply change the belt to a different design. Gatorback if you don't have one, a good Gates if you already have the Gatorback. Take a good look at the idler for the SC belt as well. Yours should be well worn by now, and that can transmit vibration through the entire belt path as 'chatter'.

From there, we'll dig further, but that'* the best I can give you for right now.

^^^ that, and check the tensioner pulley too. I had to change mine cause it was grinding really bad.

That'* what I just said

Oh, is the idler the same thing?

Tensioner/idler. Same same. Some idlers aren't on tensioner assemblies, but others are. Same idea. Usually the bearings in the pulley of the IDLER on the Tensioner that fail. You were going there, too.

With that kind of mileage i would imagine it would be the tensioner too. I am at 98k miles and mine needs changing as well.

Changed both the idler and tensioner at 110,000. They were "marginal", but the noise didn't go away... stupid failed damper!

Yup, that harmonic balancer/dampener can be a real bear to troubleshoot down to, and change. That'* another thing woodsplace should look at. Inspect the condition of the rubber backing behind the pulley tracks.

Sounds more like the same symptoms of when I cracked the flywheel on my 383 stroker last may.....That sucked to fix.