Start with a professional diagnosis. If there is a connecting rod knock, it could have been savable but any chance of that is long gone by trying to drive it further. At first the bearings will be hammered away, but within a short distance the connecting rods will start grinding on the crankshaft journals. At that point all of those parts have to be replaced, and that's when a used engine is a better choice. To replace the engine, you do want the same size and from the same year to avoid all kinds of mismatched plugs, different sensors, and brackets that don't align.
There are other things that can cause loud knocking, and if your engine uses a knock sensor, (totally unrelated to this cause), the Engine Computer will retard ignition timing in an attempt to stop that knocking, and that can reduce engine power.
A plugged catalytic converter will seriously restrict horsepower too. You wouldn't be real happy if you installed a different engine and had the same problem.
Before you replace the generator, why was the battery dead? Has anyone checked the vibration damper? If they work loose, have a cracked hub, or the outer ring breaks loose, there can be a horrendous knocking noise, and on some applications it can prevent the serpentine belt from spinning the generator fast enough. That will also cause a run-down battery.
Monday, September 1st, 2014 AT 8:28 PM