Back in Michigan, my uncle's dredge honked for weeks. I blamed worn bearings until @smith.james mentioned air in the water line, which totally made sense. His fix about warming up to purge air solved our issue too.
My cousin's dredge in Kentucky started honking after a cold night. It turned out to be air trapped in the water line. The pump diaphragm was fluttering like a goose call. Check for tiny cracks in the hoses or a loose seal on the intake. Sometimes moisture in the air compresses and makes weird noises. Ours quieted down once everything warmed up and purged the air.