Just this weekend, my tranny developed some odd sounds. At first, it sounded like a vacuum leak, and I thought it was in the motor. However, it's progressively getting worse, and sounds like it's coming from the tranny. I had the tranny serviced today, because last time it made odd noises that solved it, but it didn't help. The best I can describe it now is in park, it sounds similar to something revolving, and just barely scraping a housing or something, almost a ticking sound, but longer in duration. In gear, it becomes a hissing sound, which becomes unnoticeable when it shifts into OD. However, now upon deccelleration, and if you hang a shift (by backing off the throttle right at shift point), it makes a very high pitched whine. I know that's not an easy thing to describe verbally, but that's the best I can do. At idle, the noise definitely sounds like it's coming direcly from the tranny pan. It can't be heard under the hood. I have noticed no shifting anomalies. It's not super loud, as you can't really hear it unless the windows are shut. I don't know what good an answer to my question would be, other than, is it gonna fail, or is it just something wearing out that I can live with for a while till I can get the $$'s to get it fixed. Besides, I've had less than good luck with most mechanics diagnosing things like this. I guess it's possible it's an exhaust leak underneath, but the whining sounds mechanical, not like air. Any info would be appreciated, and I do understand if it's not good enough information to form an opinion. I had excellent luck with this board in getting problems fixed that the dealer could not diagnose. If anyone has had similar problems, help me out. It's a 99 Superduty 4 X 4 V10 with 126K miles. Thanks.

 

Mine also makes a sound like that. If hit the gas to pass someone it will sound like i have a turbo in the there, just a big suction of air sound then it shifts.

the best way to describe it is like having a turbo with a blow off valve.