I have a 1969 Mustang and I'm just going to put all pertinent information just in case it's relevant. I don't know too much about cars so for all I know some of this info might help figure out the problem. 1969 V8 302 engine 4 barrel carburetor, need any more information just ask and I'll do my best to get the info you need

So when I used to drive for like 15+ minutes it would start to run much louder. Now recently it does it all the time. The sound comes from the drivers side and I'm pretty sure it's the fan. If so does the fan need to be replaced? Is it just loose? Or does the fan run so loud because something else might be wrong?

Any and all advice is greatly appreciated, thanks!

 

I think we need to know what fan you have before passing judgement on it. You car obviously has some modifications, because there was no factory 69 302 4V, except the BOSS.

 

I'm guessing that "loud" means a lot of wind noise if you are suspecting the fan. What kind of fan are you running?

Also, I use to run an open element air filter and there was always a lot of intake noise.

I took the base off of a Mark VII dual snorkle air cleaner, removed the snorkles and use the same open element filter & lid as before and the induction noise was cut down dramatically. No more "whistle".