Rattle noise in gear.

[eric1514]

2005 Limited, 3.7gas, automatic transmission.

When idling in my driveway, there's a very noticeable rattle noise when I put the transmission in drive or reverse with my foot on the brake. If I shift to neutral or park, the noise goes away. It's kind of a "gravel in a coffee can" type noise or similar to a loose heat shield sound. This just started after I got new tires and performed a front diff and T/C fluid change, but those both seem unrelated.

Any ideas on where to start looking?

Edit to add:Weird. Went out just now to start it up. Temp is 41F outside where Jeep is and it does not make the noise. Maybe temp related?

 

[Shankster]

So when you take your foot off the brake and start moving does it continue or go away?

I think I'd get an assistant to be in the driver's seat in drive with foot on the brake while you crawl around underneath with a "stethoscope" to your ear to try to narrow in on the source - by stethoscope I mean a piece of tubing or a long screwdriver or socket extension. I'd chock all 4 wheels front and rear and situate the Jeep inches in front of a very large, immovable object to avoid getting run over and make it very clear to your carefully chosen assistant not to go anywhere near reverse while you're underneath.

 

[eric1514]

So when you take your foot off the brake and start moving does it continue or go away?

I think I'd get an assistant to be in the driver's seat in drive with foot on the brake while you crawl around underneath with a "stethoscope" to your ear to try to narrow in on the source - by stethoscope I mean a piece of tubing or a long screwdriver or socket extension. I'd chock all 4 wheels front and rear and situate the Jeep inches in front of a very large, immovable object to avoid getting run over and make it very clear to your carefully chosen assistant not to go anywhere near reverse while you're underneath.

With help, I think I've isolated the noise to the engine compartment. I'm not 100% sure yet because the noise has now disappeared. I thought the noise might be the belt tensioner, so I removed the belt and the noise disappeared. The problem is, when I put the belt back on, the noise didn't return. Even with a stethoscope I couldn't locate anything. That's confusing as is the fact that the noise was only present when the transmission was in gear.

 

[Shankster]

Hopefully it healed itself?

 

[eric1514]

Hopefully it healed itself?

I hope so, but I’m never that lucky. I’m driving around with a stethoscope on the rear floorboards just in case it returns.

 

[joshcsmith13]

I have a similar issue that I suspect is due to a cable, wiring harness, or other item bouncing against the frame. I observed this when I was forced to change the 4WD selector cable after my original got damaged. While doing that, I attempted to secure the cable and another wiring harness that seemed to be loose and rattling against the frame and, for a while, it seemed to work. Check that out. In my case, it is/was underneath the vehicle, on the driver's side, near the firewall.