I used to regularly give the 1983 240D Benz a bath underneath the hood. Even on the alternator, never was a problem. Had that Benz for 25 years.
Cannot see that you can hurt anything on any tractor except for underneath/behind the instrument panel.
If REALLY dirty, I've wetted and sprinkled Tide over the engine. Let sit and spray off. Never use a pressure washer. Gaskets and stuff on engines aren't good for those kinds of pressure. Now, with liquid Tide/detergent, could just spray on. Would still help to wet a bit first.