New rattle, torque converter area???

[JimR_TN]

So I picked up a nasty rattle on my 2007, 165k. No check engine light, my scanner could find nothing wrong, it ran and shifted smoothly on the way home. Checking it out the noise is from under the car, seems to be coming from the bell housing area. It was very loud there, not the oil pan. The oil looks fine and no sign of glitter. I checked all the heat shields and none seem to be loose and the noise didn't seem to be coming from any of them.

I pulled the inspection cover off and what I could see of the flex plate looked fine with no shiny areas or debris. The torque converter bolts I could see looked fine and the gear on the starter looked like it had plenty of clearance and didn't look worn as if it were hanging or dragging.

I'm taking it to a shop Monday, but does anyone have any ideas what this might be? Has anyone heard of these torque converters breaking where they would have a loud rattle but still function?

 

[bloodhound]

So I picked up a nasty rattle on my 2007, 165k. No check engine light, my scanner could find nothing wrong, it ran and shifted smoothly on the way home. Checking it out the noise is from under the car, seems to be coming from the bell housing area. It was very loud there, not the oil pan. The oil looks fine and no sign of glitter. I checked all the heat shields and none seem to be loose and the noise didn't seem to be coming from any of them.

I pulled the inspection cover off and what I could see of the flex plate looked fine with no shiny areas or debris. The torque converter bolts I could see looked fine and the gear on the starter looked like it had plenty of clearance and didn't look worn as if it were hanging or dragging.

I'm taking it to a shop Monday, but does anyone have any ideas what this might be? Has anyone heard of these torque converters breaking where they would have a loud rattle but still function?

I went through exactly this on my 2014. It ended up being the heat shield on the pipe that crosses over under the transmission. You couldn't tell by looking at it or hitting it. But I put a stainless hose clamp on it just to see, cranked it down, and the noise was gone. I had been convinced that it was the converter going.

 

[JimR_TN]

I went through exactly this on my 2014. It ended up being the heat shield on the pipe that crosses over under the transmission. You couldn't tell by looking at it or hitting it. But I put a stainless hose clamp on it just to see, cranked it down, and the noise was gone. I had been convinced that it was the converter going.

It didn't seem loose, but it's worth a shot putting a clamp on it before taking it in to a shop. Thanks. At this point I'm leaning toward a cracked flexplate.

 

[JimR_TN]

Update: turned out it was a broken catalytic converter. I knew that cat wasn't working, but it started to break up inside. Way louder than I expected for a broken catalytic converter. Better than engine, transmission or even flexplate.

 

[JimR_TN]

To close this one out, the shop that diagnosed the broken catalytic converter was causing the rattle gave me an estimate of $5,000 to replace just the left catalytic converter and $3,000 to use an aftermarket converter! Yikes! So I found a Walker aftermarket converter on Amazon that was marked down to $117 and a different shop installed it for $228. What at first had me dreading a possible timing job is now resolved for a reasonable price and my exhaust no longer stinks.

By the way the day after I ordered it the Walker converter was back up to $468 on Amazon so I must have gotten lucky and the part I needed was overstocked or something.

And I am still surprised just how loud the converter rattle was. I've heard of converters breaking apart inside but I've had motors that actually did have a rod knock that weren't nearly this loud.

 

[Motorcity muscle]

Had a converter start whistling one day when you accelerated, had them both replaced, $1,400.