VOLVO PENTA 230 250 251DOHC AQ131 AQ151 AQ171 WORKSHOP FACTORY REPAIR SERVICE MANUAL 230, 250, 251DOHC AQ131, AQ151, AQ171 This Workshop Manual contains technical data, descriptions and repair instructions for Volvo Penta products or product versions contained in the contents list. Safety Precautions .............................................................................. 2 General information ............................................................................ 5 Repair instructions ............................................................................. 6 Presentation ........................................................................................ 8 Trouble-shooting Scheme ..................................................................11 1. Overhaul Data ...............................................................................12 2. Special Tools ................................................................................20 3. Electrical System .........................................................................23 Wiring Diagram AQ131, AQ151, 230, 250 Alt. 1. ........................24 Wiring Diagram 230, 250 Alt. 2 ..................................................26 Wiring Diagram AQ171, 251DOHC Alt.1. ..................................28 Wiring Diagram 251DOHC Alt. 2 ...............................................30 4A. Fuel System ..................................................................................32 Trouble shooting and Remedies Fuel System ............................32 Overhauling and checking the carburetor ...................................33 4B. Renix Ignition System..................................................................38 Trouble-shooting and repair ignition system 251DOHC, AQ171 38 4C. Cylinder Head ...............................................................................44 Removal of teh external components .........................................44 4D. Cooling System ............................................................................48 Overhauling the heat exchanger .................................................48 Overhauling the sea water pump ................................................49 Check the thermostat..................................................................49 4E. Overhauling the valve system .....................................................50 Overhauling the valve system 230, 250, AQ131, AQ151 ...........50 Adjusting the valves 230, 250, AQ131, AQ151 ..........................59 Valve system 251DOHC, AQ171. Technical Description ...........61 Overhauling the valve system 251DOHC, AQ171 ......................63 4F. Installing the toothed belt ...........................................................71 Installing the toothed belt 230, 250, AQ131, AQ151 ......................71 Installing the toothed belt 251DOHC, AQ171.................................73 4G. Installing the external components of the Cylinder Head ........74 5. Cylinder Block ..............................................................................78 5A. Removing the external components ...........................................78 5B. Overhauling the Crank Assembly ...............................................80 The lubricating oil pump Overhauling..........................................87 5C. Installing the external components ............................................93 Overhauling the oil cooler 250, 251DOHC, AQ151, AQ171 ........95 Workshop Manual