I was out driving my 03 gs300 (160k miles) bought it a few days ago and it drove great on the test drive. I was having a little fun last night, nothing crazy, just a pull, and then noticed what I first thought was rod knock. I quickly drove home to inspect further, I then noticed the giant puddle of trans fluid pouring out of the bell housing where it mates to the block. I listen around a bit and find I can’t hear it much from the engine bay, but more so near the transmission. I haven’t done to many tests yet, but it seems to go up with revs and gets quieter the higher the rpm’s till it’s almost unnoticeable, I got some videos that I’ll post here as well. Any help would be appreciated

 

That is one serious transmission oil leak. I hear an exhaust leak not rod knock or flex plate rattle. But something is seriously messed up with your transmission.

 

I plan on swapping in a new transmission, how can you tell it’s an exhaust leak? I can take more vids if you want

 

Can't be sure but that's what it sounds like. And could be combined with a misfire. Rod knock is a very sharp sound like hammer on anvil.

 

I did see a lot of dripping coming from the exhaust manifold area as well if that means anything, here’s another sound video with some light revs, video taken near the drivers side front wheel well

 

I am not able to hear your files as they all require downloading. Not possible on my device - can you load them somewhere to share? If you genuinely want them heard, host them somewhere.

Has the transmission been rebuilt before? Most common cause on this is a rebuilt trans, badly installed/rebuilt, and failed front seal. Re-intalling a transmission and not trashing the front seal is an art. Most transmission rebuilders cannot do it.

Did you red-line the car on the test drive? (You should have). People crap on me for doing that, but if an engine will not make rated power on a test run, without clear signs of imminent failure, why buy it? In aviation and marine circles, a full-power test run before purchase is understood to be standard, and 3rd party experts are usually hired to verify it. No kidding.

 

to my knowledge it has not been rebuilt before, and no i never thought to redline it during test drive, but i did give it a pull, and nothing went wrong. here are the links to the videos in youtube form

 

My flex plate went bad. We put it on a lift and removed the inspection hole cover. You could hear the rattle when tapping on the flex plate. Not sure about that leak tho.

 

My flex plate bolts backed out. It was only audible when moving slowly and idling, both in and out of gear. It sounded much different from yours.

 

I believe I had a similar noise that drove me crazy similar to that. I replaced the tensioner pulley and problem solved. Hard to really tell over the phone. Good luck.

 

Figured out the issues, previous owner did a transmission rebuild of some sorts, he ended up installing the flex plate backwards, in fear of what all that misalignment might have caused, i got a new (to me) transmission installed as well as a torque converter