I am thinking of jumping in to the Jeep world and buying a 2.5L 2000 Wrangler SE from a friend with 127,000 miles on it. Seems to be in reasonable condition and well maintained with a couple very minor issues. The only hesitation I have is that at 2,750 RPM and above the engine begins a high pitched whine, almost like a transmission gear or some sort of bearing failing / turbocharger kind of sound.
It does it when in gear and out of gear, moving and not moving so I know it is not drivetrain related. It does whether the AC is on or off i.e. it does not seem to vary with compressor load. As the RPMs increase to 3,000 - 3,250 RPM the whine gets louder - the volume is driectly proportional to engine RPM. Its not a belt squeal - it has too much of a metallic sound for that.
I poked my head around the engine bay but couldn't get a bead on where it is coming from. I spent a week with the vehicle before I noticed it and that was only when I was driving with the top up, AC and radio off trying to listen for - well - alarming noises. The owner hadn't even heard as he usually has the top down and raido on when he drives it as a second, fun car.
Has anyone experienced this? Is it a common "its just old and makes that noise thing"? Alternator or some such going? Or is this the sign of something fatal like the start of a main bearing failure?
Any help would be greatly appreciated - as it could help make the decision to move forward. I poked around the forum but could not find any description of symptoms that matched what I am hearing.