Brother (and sister) brickers:

My extremely-loved daily driver brick (1990 240, 229,000 mi.), which is mostly used for in town local driving, has been taken out on the highway a couple times recently for about 40 and 60 mile drives. (I was sick of not taking this baby for real drives, hence the recent trips; heck, I can let my 93 245 and 93 240 sit a little bit, can't I?)

But, after getting off the highway and stopping at the stop light near my house, I got what I refer to as an "rpm-related" noise, when idling at the light and when getting up to about 10 mph; I think it went away after that, but I was so close to home can't say what would have happened if I had kept driving.

The noise is difficult to describe except to say that it seems to be rpm related and is coming from the engine. It's repetitive, and increases in frequency as I pick up speed. If I got up to more than 10 or 20 mph I think it does or would go away. It is not a sreeching sound like I think of as a slipping belt, but I suppose it could be a belt. I bought the car used and I believe the timing belt was changed at 150K (yes, I know it's time for a new one, but until recently I had been operating under the impression that it had been changed at 190K).

Any of you fabulous gurus have a good idea what it might be? I should state that the car drives fine when making this noise (except for the noise, of course).