2000 ford ranger 6 cylinder engine is making a taping noise?

I left it set more a couple months and now it is making a taping noise when I start it. My friend had a stethoscope with a rod on it… He held it to the valve covers and block to listen. I heard nothing on valve cover and only heard it slightly on the block, but it was really loud on the alternator… Does that mean it is my alternator? How accurate is a stethescope? Also, the battery was dead and we jumped it… Not sure if that matters… Any ideas?

A "tapping noise" on startup is usually a hydraulic lifter that is slow to pump up to full pressure. Try changing the oil and filter. A dead battery after the car has been sitting for a couple of months is not unusual, and as long as the battery is recharged after running for a while, it should be OK.

Chances are one of the hydraulic lifters bled down and stuck while it was sitting. Drive it for 15 minutes until it's hot and I bet it stops, but change the oil to help clean them out.

If the car has been sitting for a while that can happen. Hydraulic lifters can bleed out and cause that. Looks like a temporary problem and should resolve itself with time. However, I highly recommend you on changing the oil. Oil doesn't have to clock up the kms to get changed. It still detoriates sitting in the engine over time. So give it a fresh oil with new filter and problem should be fixed.

HI, if it does it all the time now then you run it what you have is a sticking/gumed up lifter. Add1 qt of automatic transmission fluid thru the oil for a 100 miles or so then change it out with a new filter too. It well un-stick/unplug the lifter. I've done it many times and it well clear it up. Or should.