I know the sound you're speaking off. I thought the same thoughts. I decided to run it again. Repair bill was $600 and change and boy did the sound get louder when I ran it!!

Granted, it was a RAM engine, but the logic would seem to support across all brands. If it's making a noise, it's not right. In my case, I had Carlos on the phone listening to it and I was trying to determine as to whether there was a real problem or not cause the next day I was travelling to a Jet Meet pretty far away and I didn't want to get there and have a problem, so I kept running it till I had a verified problem rather than a questionable one. Didn't spend the money getting to the meet, but did pay for service.

At least with the Jetcat engine, you know when you get it back it will not likely fail again for quite a while.

Good Luck,

Sean