My trusty 98 Fronty I've had since new has developed a whine somewhere in the engine bay. It's the 2.4 DOHC, automatic with 189,000 miles on it. Anyway, the whine started off and on a couple of months ago when it was cold and go away after a couple miles. It's developed into a constant whine with an underlying tingy rattle. My (non Nissan) mechanic had it today and can't find it. He took off all the belts, ran it and the noises were still there. The noise is such that it sounds like it's coming from everywhere. I thought it was the trans, but he doesn't. The truck drives, runs and shifts as always. the whine is RPM dependent. It still whines in neutral while coasting and the whine gets louder with higher RPMs. I think it may be the timing chain or a bearing going on the oil pump. Anyone have a thought on my problem? Is the 2.4 an interference engine if the chain lets go? I know it has allot of miles on it, but I've replaced some key parts on it (gas tank , fuel pump, leaf springs, shocks, calipers and such) and hate to give it up for unknown problem. I'm afraid it's a catastrophic failure coming soon.