I have a 1998 Ford Ranger Splash edition V6 4.0, and its been running great. I have been noticing this tumbling sound that seems to be comming from underneath the truck from my engine. Latly it has been getting louder and a little more faster of a tumble. Its not a piston knock or anthing like that because we put a stethascope up to the engine and ruled out certian parts of the engine. But we cant find where its comming from. I was hoping someone would be able to help me answer this question because they have had the same problem. I dont wanna take it into a mechanic just yet because its like 70 bucks. Any advice would help thanks a bunch and happy holidays