no its in the tractor still . it does kinda sound like its coming from that area though .
Old school, cheap, tried and true method for the cast iron engines, many still laugh at me all day for this but then I find the problem and ram it up their @ss sideways. I check for loose valves and tune it on multi-cylinder engine this way too.
Use a long handle screw driver, put it over the spot the sound is coming from and put the handle into your ear and listen carefully moving the screwdriver to different spots. Both valves should sound like a sewing machine, intake will have slight pinging which is normal, exhaust is less because the gasses dampens the taping and of Stellite instead of harden/treated steel. Check the crank by placing the screwdriver by the PTO shaft seal, if the rod cap is loose it will knock after TDC due to rod return flex after compression stroke at low rpms. If the knock is pronounced when engine under load, weight of tractor driving up hill or spinning a mow deck then it is the rod cap or sometimes piston wrist pin.
Pull the head and check the valves as I stated in other post. Check rod cap to crank play while head is off and check head gasket, a leak will exhibit tapping/knocking sounds at low rpms.
Upload a video from a good camera or new smart phone for us to listen to.
Edited by trowel, May 13, 2015 - 03:21 AM.