Once you’ve got the engine out, clean it off. We were in full hantavirus-phobia mode with this one, thanks to all the rodent droppings. However, we’ve had great results with using oven cleaner over the years. That is, as long as you don’t care about paint or most anything else. Spray it on, let it bubble and go from white to some yellowish-brownish color, maybe scrub a bit, and rinse off. Well, in this case, we stayed at arm’s length to avoid breathing anything in.