Hey Guys,

So I started hearing the hissing type rattle under acceleration only. Sounds like if you put bbs in a tin can and shook the can real fast. Only with throttle. Goes away with foot off gas. Happens driving and neutral but less in neutral.

I popped under the car and gave it some gas with a long lever to see if I could pinpoint the area. Kind of looks like it’s coming from either where the trans meets the engine or somewhere around the engine oil pan. Can’t tell.

But what was even more concerning is when I was revving the engine up to hear the noise, when the engine would slow down from like 2.5k to idle quickly, I’d hear a pretty audible “knock knock thud” coming from what sounds like directly under the engine.

I was able to repeat the noise several times. Didn’t do it every time but probably 2 out 3 times on average.

I’ve done a ton of maintenance recently so hard to pinpoint. But I did do a full trans fluid transfer using the pump method with Valvoline max life, 150 miles ago. I checked the fluid level after using the “warm hand” procedure. Pretty sure the fluid level is correct.

The knocking scares the heck out of me and I have to drive to Vermont tomorrow (500 miles).

Any thoughts are welcome.