1999 ranger 3.0 knocking only at low rpms
 

so I've owned this truck for 7 months I bought it with the knock assuming when the engine went I'd put a crate motor in it the guy I bought it off of said it started knocking 6 months before he sold it to me its a constant " knock knock knock" it isn't pinging but a knock I can hear it up by the bank 1 valve cover and also at the bottom of the pan so I can't put my finger on it. first thought is it has to be the rod bearings but 7 months of daily driving you would think the sound would get worse or the engine would break but nothing it drives fine has great power I only hear the knock at idle and up to 2000 rpm after that it goes away any help would be greatly appreciated

What weight motor oil are you running? Personally, I wouldn't worry about it unless the sound really bothers you. Since you already anticipated spending the money on a crate motor, I would save the $$$ for now and just run the engine until it spits it guts...Which by the way may be a while. The Vulcan engine is a pretty stout engine. I've seen a few Rangers and Taurus' with close to and over 300K miles on them. I had a friend that took his 200K+ mile 2001 Taurus with the 3.0 Vulcan that had a knock and thought it would be a good idea to drink some beer and see if he could kill the engine. So...He filled the gas tank up, started the engine and put a brick on the gas petal and we proceed to drink beer and have a BBQ while the engine ran at the 4K RPM rev limiter. We ran out of beer and the Taurus ran out of gas without even a burp from the engine. So he drove it for another year before trading in the car with the engine still knocking...Go figure...