If it's got an unidentified heavy noise go easy on the revving and loading of the engine or you can end up like the owner in the story below.
On about the third day of a new job, the foreman sent me out into the yard to see about a 5-ton corn binder that had come in on a hook. All he said was it had a bad miss and a bad oil leak. First thing I did was open the hood and check the oil. It was about three qts low. So I put oil in it and started it up. Ran nice and quiet - on 5 cylinders. But as I reved it up I noticed a strong vibration; enough to shake the mirrors. So I shut it down to have another look under the hood. But as I walked around from the cab to the engine, I slipped in a puddle of oil. I got some floor-dry to sop up the oil and crawled under the engine to have a look. A couple of inches above the oil pan was a hole in the block about six inches by 8 inches. Inside I could see the bottom third of the connecting rod still attached to the crank throw.
Back to the foreman. "They need a new engine." I said. Aw baloney," he replied. "The owner said it's been making some noise but since the noise quit it started missing and lost power. Check the plugs and pull the valve cover."
