Hey guys. I posted here a couple weeks ago about my 1993 f150, 4.9L. You guys helped a ton and I got it running again, so thank you.

However, now when I shut the engine off it makes an air rushing sound. If you are standing on the passenger's side looking at the engine, it seems like the sound is coming from the right side of the air plenum, or in that area.

I don't know if it is air rushing in, or out, or if when I fixed the truck and replaced the gaskets it made I better seal and now that is why I am hearing it? (that would be nice).

I checked for vacuum leaks and it seems to be fine all around. I sprayed starter fluid all over the area to check for idle engine changes, but also heard no change.

Any ideas? I would appreciate some help or insight.

I don't know if performance is worse than it was before, I had the truck out of commission for a while so I can't tell if it runs differently now than before when I didn't hear the sound. Seems the same.

Normal? Something to worry about? thank you

 

https://drive.google.com/a/timberfor...ew?usp=sharing

Link to a video I took of the sound when shutting the engine off.