This does not get much into the engine bay
the only mechanicla probs I have had from it is excessive wear on the rear drums.
Deep mud on the other hand can destroy wheel bearings, alternators, idler pulleys, mud gets caked into the frame and becomes a percursor to accelerated corrossion because it traps moisture, and some mud will stain paint
. Deep mud is also accompanied by "lotsa" water that can get into differentials, trannies and be ingested by the motor... Also the grit carried by the mud can get into seals and cause leaks down the road.
I will encounter mud on certain trails and will navigate it carefully and minimally and not travel off the trail to avoid it, on the other hand if it is possible to avoid mud and water, I do.
If my words are not enough to make you avoid mud to preserve a vehicle mechanicly then I will dig up some stories for you. I love offroading, in sand and the rocks, but I learned real soon that mud is the devil.