uncletiffy

09 JKU automatic. I am getting a noise. Whenever I am in drive and am going along and take my foot off the accelerator pedal to coast I am hearing a noise. It sounds like what you hear when there is something loose on an exhaust system, like a light rattle that seems to slow as the vehicle slows. Its not that loud, when the windows are up and AC on I cannot hear it. Today I tried putting the transmission in neutral while I was coasting , the noise did not go away. any thoughts as to what I should check? Thanks.

resharp001

Possibly a loose heat shield underneath vibrating a bit due to the wind passing by it? That would be the first thing I checked. Does the sound change with the rate of speed?

uncletiffy

Yes, the noise seems to slow down as I slow down coasting. It sounds like a heat shield but why only when I coast?

resharp001

I was just thinking it might be quieter coasting, so you notice it moreso than it wasn't there at all while on the gas. I've never had a heatshield issue, but seems to be common on our JKs. Dang rattles are always the hardest to track down since you typically have to be in motion to reproduce them.

uncletiffy

I also noticed when I was underneath looking for rattles that my front drive shaft was really hot, almost too hot to touch.
Could the noise be a failed U-joint ?

resharp001

If you have a bad u-joint, you should be hearing a clicking sound, but it would be constant, not just when coasting......unless again other noises are just drowning it out while on the gas. If you have a bad u-joint, you should be able to get under there, get both hands on it and feel some play while giving it a good shake with your hands. There's obviously going to be some rotational play due to the backlash in the gears, but you should be able to feel the play in the u-joint if it's there. Your profile is not updated with details, so hard to tell what your set up is. Depending on your lift and geometry angles, that joint might just be working pretty hard and generating some heat due to the angles.

uncletiffy

Absolutely stock suspension , running 33x12.5 tires on stock wheels. I felt both drive shafts and they felt fine and solid. My next move will be checking fluids in the transfer case and diff. What oils are used in the TC and Diff? Thanks.

resharp001

TC should be Mopar ATF 4+. You should be able to pull the fill plug on the TC and just feel if it's full or not. You pretty much fill that till it starts coming back out. Should be changed every ~30k miles.....takes 2 qts. You might just want to do it anyhow. Quick write up on it -

Jeep JK Wrangler NV-241 / NV-241OR Transfer Case Service ? Project-JK.com

Diff oil gonna depend a bit more on what you have. If you have limited slip be sure to use a gear oil with additive. I prefer synthetic and use 75W90 myself.

uncletiffy

Thanks !

resharp001

If you change the TC fluid, do yourself a favor and grab a pump like this -

Performance Tool W1139 - Fluid Pump | O'Reilly Auto Parts

Will make life easier. Also, you'll probably need a 10mm allen head socket if you don't have one already....if the '09 TC is the same.