BIG BLU

2009 JKU, 37" tires, 4.88s, ARB snorkel intake kit, 3.8 auto. When the engine appears to be under higher torque (turning and going up an incline), I get this mid-pitched whine. Not like an alternator going out. It almost sounds like an older riding lawn mower when letting off the clutch/brake and the blades are spinning and the belt is slipping along the pulleys a bit. It is hard to explain. But it is only when I am accelerating and beginning an ascent (climb) regardless of steepness. And it is only brief and fades, not a drastic stop. I've owned the jeep for going on three years, but I have not modified the engine/transmission/transfer. It has had a G2 Core 44 front end for two years. Did it in reverse today on an incline too.

austin160

That will be hard to figure out without hearing. Check your inbox, I'm local and can meet up to listen to it if you need some help.

lucky5

Does the whine come through the speakers or just the engine area?

GullandMichael

Auto or manual?

BIG BLU

3.8 Auto and it comes from the engine area. Not through the speakers (although I know where you were going with that as I've had that before in a different vehicle)

BIG BLU

3.8 auto. No slipping or jerking in the transmission accompanying the whine. I am wondering if the serpentine belt is just worn and too slick and slipping. Tension seems good, and I didn't see any dry rot or cracking.

lucky5

I would check the belt and belt tensioner. Also, not familiar with the 3.8, but could possibly be coming from an bad bearing in the idler pulley, but most of the ones I've seen go bad have a grinding noise coming from them. A bad tensioner could cause belt slippage and the squeaking.

BIG BLU

What are the specs on the tensioner (ftlbs of torque on the pivot bolt, belt tension, etc)? I haven't looked it up yet though. My tensioner moves pretty easily when touching it. Pushing the belt even makes the tensior move pretty easy.

lucky5

You shouldn't be able to move the tensioner by hand. It should be fairly hard to move. The bolt that holds the tensioner to the block doesn't do anything but hold it to the block. I would just make sure it's good and tight. There is a spring built into the tensioner that keeps resistance on the belt. If you are able to move it by hand, I would go ahead and replace it. Here is one for $30. Might could check with local parts stores and find one in stock and have it the same day.

Crown Automotive 53032860AA Belt Tensioner for 07-10 Jeep® Wrangler & Wrangler Unlimited JK with 3.8L V6 Engine | Quadratec

Here is a list of common engine torque values for the 3.8L.

Jeep Wrangler JK Engine Torque Specs | ExtremeTerrain

lucky5

Also, I would replace the belt while you have the old one off. Better safe than sorry.