I had that hissing noise you mention and it turned out to be my tranny fluid pump. It was clogged or something. I changed the filter and tried to flush the fluid by draining and adding over and over again until it got to the point where I was getting no where as the fluid was hardly changing color. I decided to just start the thing and run it through the gear while in the air with the tranny pan off. I had someone else do that while I was under it. Immediately after firing it up it you heard it unclog and all this thick nasty tranny fluid came pouring out. I assume from up in the TC. It looked like muddy chocolate milk. After that I filled it with fresh fluid and drained it again. Filled it one more time put the filter on, cleaned the magnets and put the pan back on. Amazingly it drove better than it ever had since I owned it after that. No whine or that hissing anymore. Unfortunately that was for like 3 weeks, until it just stopped working and needed to be rebuilt. See my thread "Horror from Underneath". I forgot who, but someone posted a video of the whine that you get before the tranny goes. I know the hiss you are talking about because I had it and its not to be confused with the whine in the video.

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