Description Raw water engine cooling pump (bronze housing) for Onan 4‑cylinder diesel generator models MDL3 (12.5 & 15 kW) and MDL4 (20 kW); features 1‑inch inlet and outlet ports, mechanical seal, installed neoprene impeller; replaces Onan parts 132‑0275, 132‑0278 and Sherwood models K‑75B, K75B, K75, K‑75.