Flow directions in engine cooling hoses (both early and B-series engines)
The top schematic indicates the engine coolant and raw water cooling water flow for earlier engines (M-25/XP/XPA, M35/A) engines.
The coolant loops on the B-series (M-25XPB, M-35B) are identical (bottom pix,) except that the hoses are in somewhat different locations.
Cooling loops for earler engines
Coolant flow on B engines (M-25XPB shown)
--KWKloeber 2 February 2019