Water Pump Suction Pipe connects to the front the engine block, and is the inlet for the the cooling system.
Overview
Part Numbers
Regular 1200 uses a straight pipe.
21045-18000 PIPE-SUCTION WATER PUMP 21045-H2300 PIPE-suction, water pump GX
The GX water pump inlet pipe at front of block (PIPE-suction, water pump) has an additional hose fitting for the manifold coolant hose.
Regular B210 uses a pipe with one small hose connection.
21045-M0100 A12S B210 [one small fitting] 21045-M0800 A12T B210 [two small fittings, one straight up] 21045-H8400 A14T B210 [two small fittings]
Left: A14T (21045-H8400). Right: 21045-M0100
21045-H8400 B310 A12S.Sedan,A12S.Coupe,A14.V,A13,A15 21045-H8410 B310 A14S.Sedan,A14S.Coupe with AT, A15S 21045-M0100 B310 Van <> 21045-M0110
Removal
The suction pipe is a press fit into the block. Put vice-grips on it and tap the vice-grips until the pipe comes out.