So I'm still getting up to speed on my new-to-me 2000 sport 4.0. It doesn't overheat. Runs really smoothly. Only check engine light is the 01495 that I'm getting looked at because I've tried everything I can think of. I'm still trying to figure out what I want long term, so I'm wondering if anyone can tell me what the engine means when it's rattling like this.

P.s. I already sent an oil sample to Blackstone. Fresh oil change. New plugs. Compression test passed.

I've put about 100 miles on it so far.

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Is it coming from the top end, or the bottom? And is that hissing from the microphone, the fans, or a vacuum leak?

 

That hissing is definitely the microphone or fans. There is no audible vacuum leak. Aside from that rattling/knocking, the engine sounds good. I think I need to work on the exhaust some though.

I don't know how to tell if it's from the top end or the bottom,

 

Stethoscope. Or use a screwdriver, with the handle to your ear, and the pointy end on whatever it is you want to listen to. Shove a rubber hose over the end of it for longer reach, if needed. Either way, keep clear of the fan.