I have a 1994 mazda b4000 with the 4.0 V6 with only 108,000 miles and it makes a loud noise that sounds like it’s sucking air. The noise stays consistent at idle and acceleration. The sound is kind of low pitch and it’s not a whine or anything. It almost sounds like a garbage truck because of how loud it is. I was thinking it could be some sort of intake leak or something along those lines but I’m wondering if it’s something else, thank you!

 

Welcome to the site. Have you looked for a disconnected vacuum hose?

 

I looked around a bit but not too deep, I might have a look tomorrow.

 

Welcome to the forum

After engine is warmed up is the idle under 800rpms?
If so then no vacuum leak
And you didn't mention high idle so I assume that seems OK in any case

Lower frequency sound is most likely an exhaust leak
With engine idling have someone put their GLOVED HAND over the tail pipe, while you listen for a change in the sound and location of the leak
IF...........you have an EGR Valve its exhaust tube can leak, 1994 4.0l may or may not have an EGR valve

Long shot
There is an air pre-heater between Air Filter box and Rad support, passenger side front of engine bay
It has a flexible air tube attached, there is a vent/flap inside the Cold Air Intake tube, this flap opens when cold and sucks in air from around the exhaust manifold, pre-heated air, this helps engine warm up faster

Longer shot
With engine COLD
Remove fan belt from crank pulley
Start engine, battery light will stay on
Engine bay will be VERY QUIET with no fan or accessories turning
See if noise is gone, or it you can localize it
Don't run engine longer than 2 minutes or it will over heat, because there is NO WATER PUMP

If noise is gone then its an accessory issue, shut engine off
Spin accessories to see which one is making the noise