VOLVO PENTA AQ131 AQ151 AQ171 Marine Engine Workshop Repair Manual

Engine 230, 250, 251DOHC AQ131, AQ151, AQ171 Workshop Manual 2(0) C

1 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 Index 230, 250, 251DOHC, AQ131, AQ151, AQ171

2 Safety Precautions Check that the warning or information decals on the product are always clearly visible. Replace decals that have been damaged or painted over. Engine with turbocharger: Never start the engine without installing the air cleaner (ACL). The rotating compressor in the Turbo can cause serious personal injury. Foreign objects entering the intake ducts can also cause mechanical damage. Never use start spray or similar to start the engine. The starter element may cause an explo- sion in the inlet manifold. Danger of personal injury. Avoid opening the filler cap for engine coolant system (freshwater cooled engines) when the engine is still hot. Steam or hot coolant can spray out. Open the coolant filler cap carefully and slowly to release pressure before removing the cap completely. Take great care if a cock, plug or engine coolant line must be removed from a hot engine. It is difficult to anticipate in which direction steam or hot coolant can spray out. Hot oil can cause burns. Avoid skin contact with hot oil. Ensure that the lubrication system is not under pressure before commencing work on it. Never start or operate the engine with the oil filler cap removed, otherwise oil could be ejected. Stop the engine and close the sea cock before carrying out operations on the engine cooling system. Only start the engine in a well-ventilated area. If operating the engine in an enclosed space, ensure that exhaust gases and crankcase ventilation emissions are ventilated out of the working area. Introduction This Workshop Manual contains technical data, descriptions and repair instructions for Volvo Penta products or product versions contained in the contents list. Ensure that the correct workshop literature is being used. Read the safety information and the Workshop Manual “General Information” and “Repair Instruc- tions” carefully before starting work. Important In this book and on the engine you will find the following special warning symbols. WARNING! If these instructions are not followed there is a danger of personal injury, ex- tensive damage to the product or serious mechanical malfunction. IMPORTANT! Used to draw your attention to something that can cause damage, product malfunction or damage to property. NOTE! Used to draw your attention to important information that will facilitate work or operations. Below is a summary of the risks and safety precautions you should always observe or carry out when operating or servicing the engine. Immobilize the engine by turning off the power supply to the engine at the main switch (switch- es) and lock it (them) in the OFF position before starting work. Set up a warning notice at the engine control point or helm. Generally, all servicing should be carried out with the engine switched off. Some work (carrying out certain adjustments for example) requires the engine to be running. Approaching a running engine is dangerous. Loose clothing or long hair can fasten in rotating parts and cause serious personal injury. If working in proximity to a running engine, careless movements or a dropped tool can result in personal injury. Avoid burns. Take precautions to avoid hot surfaces (exhausts, turbochargers, charge air pipes and starter elements etc.) and liquids in supply lines and hoses when the engine is running or has been turned off immediately prior to starting work on it. Reinstall all protective parts removed during service operations before starting the engine.

3 Always use protective goggles where there is a danger of pieces of metal, sparks from grinding, acid or other chemicals being thrown into your eyes. Your eyes are very sensitive, injury can lead to loss of sight! Avoid skin contact with oil. Long-term or re- peated contact with oil can remove the natural oils from your skin. The result can be irritation, dry skin, eczema and other skin problems. Used oil is more dangerous to health than new oil. Use protective gloves and avoid using oil- soaked clothes and rags. Wash regularly, es- pecially before meals. Use the correct barrier cream to prevent dry skin and to make cleaning your skin easier. Most chemicals used in products (engine and transmission oils, glycol, petrol and diesel oil) and workshop chemicals (solvents and paints) are hazardous to health Read the instructions on the product packaging carefully! Always follow safety instructions (using breathing appa- ratus, protective goggles and gloves for example). Ensure that other personnel are not unwittingly exposed to hazardous substances (by breathing them in for example). Ensure that ventilation is good. Handle used and ex- cess chemicals according to instructions. Be extremely careful when tracing leaks in the fuel system and testing fuel injection nozzles. Use protective goggles! The jet ejected from a fuel injection nozzle is under very high pressure, it can penetrate body tissue and cause serious injury There is a danger of blood poi- soning. All fuels and many chemicals are inflammable. Ensure that a naked flame or sparks cannot ignite fuel or chemicals. Combined with air in certain ratios, petrol, some solvents and hydrogen from batteries are easily inflammable and explosive. Smoking is prohibited! Ensure that ventilation is good and that the necessary safety precautions have been taken before carrying out welding or grinding work. Always have a fire extinguisher to hand in the workplace. Store oil and fuel-soaked rags and fuel and oil filters safely. In certain conditions oil-soaked rags can spontaneously ignite. Used fuel and oil filters are environmentally dangerous waste and must be deposited at an approved site for destruction together with used lubricating oil, contaminated fuel, paint remnants, solvent, degreasing agents and waste from washing parts. Never allow a naked flame or electric sparks near the batteries. Never smoke in proximity to the batteries. The batteries give off hydrogen gas during charging which when mixed with air can form an explosive gas – oxyhydrogen. This gas is easily ignited and highly volatile. Incorrect connection of the battery can cause a spark which is sufficient to cause an explo- sion with resulting damage. Do not disturb battery connections when starting the engine (spark risk) and do not lean over batteries. Never mix up the positive and negative battery terminals when installing. Incorrect installation can result in serious damage to electrical equipment. Refer to wiring diagrams. Always use protective goggles when charging and handling batteries. The battery electrolyte contains extremely corrosive sulfuric acid. If this comes into contact with the skin, wash immediately with soap and plenty of water. If battery acid comes into contact with the eyes, immediately flush with copious amounts of water and obtain medical assistance. Turn off the engine and turn off power at main switch(es) before carrying out work on the electrical system. Clutch adjustments must be carried out with the engine turned off.

4 Use the lifting eyes mounted on the engine/reverse gear when lifting the drive unit. Always check that lifting equipment is in good condition and has sufficient load capacity to lift the engine (engine weight including reverse gear and any extra equipment installed). To ensure safe handling and to avoid damaging engine components on top of the engine, use a lifting beam to raise the engine. All chains and cables should run parallel to each other and as perpendicular as possible in relation to the top of the engine. If extra equipment is installed on the engine al- tering its center of gravity, a special lifting de- vice is required to achieve the correct balance for safe handling. Never carry out work on an engine suspended on a hoist. Never remove heavy components alone, even where secure lifting equipment such as se- cured blocks are being used. Even where lifting equipment is being used it is best to carry out the work with two people; one to operate the lifting equipment and the other to ensure that components are not trapped and damaged when being lifted. When working on-board ensure that there is sufficient space to remove components without danger of injury or damage. Components in the electrical system, ignition system (gasoline engines) and fuel system on Volvo Penta products are designed and con- structed to minimize the risk of fire and explo- sion. The engine must not be run in areas where there are explosive materials. Always use fuels recommended by Volvo Pen- ta. Refer to the Instruction Book. The use of lower quality fuels can damage the engine. On a diesel engine poor quality fuel can cause the control rod to seize and the engine to overrev with the resulting risk of damage to the engine and personal injury. Poor fuel quality can also lead to higher maintenance costs.

5 General information About the workshop manual This workshop manual contains technical specification, descriptions and instructions for repairing the standard versions of the following engines 230, 250, 251DOHC, AQ131, AQ151 and AQ171. The product designation and number should be given in all corre- spondence about the product. This Workshop Manual has been developed primarily for Volvo Penta service workshops and qualified personnel. Persons using this book are assumed to have a grounding in marine drive systems and be able to carry out related mechanical and electrical work. Volvo Penta is continuously developing their products. We therefore reserve the right to make changes. All the information contained in this book is based on product data available at the time of going to print. Any essential changes or modifications introduced into production or updated or revised service methods introduced after the date of publication will be provided in the form of Service Bulletins. Replacement parts Replacement parts for electrical and fuel systems are subject to statutory requirements (US Coast Guard Safety Regulations for example). Volvo Penta Genuine parts meet these requirements. Any type of damage which results from the use of non-original Volvo Penta replacement parts for the product will not be covered under any warranty provided by Vol- vo Penta.

6 Repair instructions The working methods described in the Service Ma- nual apply to work carried out in a workshop. The engine has been removed from the boat and is installed in an engine fixture. Unless otherwise stated reconditioning work which can be carried out with the engine in place follows the same working method. Warning symbols occurring in the Workshop Manual (for their meaning see Safety information) WARNING! IMPORTANT! NOTE! are not in any way comprehensive since it is impos- sible to predict every circumstance under which service work or repairs may be carried out. For this rea- son we can only highlight the risks that can arise when work is carried out incorrectly in a well- equipped workshop using working methods and tools developed by us. All procedures for which there are Volvo Penta special tools in this Workshop Manual are carried out using these. Special tools are developed to rational- ize working methods and make procedures as safe as possible. It is therefore the responsibility of any person using tools or working methods other than the ones recommended by us to ensure that there is no danger of injury, damage or malfunction resulting from these. In some cases there may be special safety precautions and instructions for the use of tools and chemicals contained in this Workshop Manual. These special instructions should always be followed if there are no separate instructions in the Workshop Man- ual. Certain elementary precautions and common sense can prevent most risks arising. A clean workplace and engine eliminates much of the danger of injury and malfunction. It is of the greatest importance that no dirt or foreign particles get into the fuel system, lubrication system, intake system, turbocharger, bearings and seals when they are being worked on. The result can be malfunction or a shorter operational life. Our joint responsibility Each engine consists of many connected systems and components. If a component deviates from its technical specification the environmental impact of an otherwise good engine may be increased significantly. It is therefore vital that wear tolerances are main- tained, that systems that can be adjusted are adjusted properly and that Volvo Penta Genuine Parts as used. The engine Maintenance Schedule must be followed. Some systems, such as the components in the fuel system, require special expertise and special testing equipment for service and maintenance. Some components are sealed at the factory for environmental reasons. No work should be carried out on sealed components except by authorized personnel. Bear in mind that most chemicals used on boats are harmful to the environment if used incorrectly. Volvo Penta recommends the use of biodegradable degreasing agents for cleaning engine components, unless otherwise stated in a workshop manual. Take special care when working on-board, that oil and waste is taken for destruction and is not accidentally pumped into the environment with bilge water. Tightening torques Tightening torques for vital joints that must be tightened with a torque wrench are listed in workshop manual “Technical Data”: “Tightening Torques” and are contained in work descriptions in this Manual. All torques apply for cleaned threads, screw heads and mating surfaces. Torques apply for lightly oiled or dry threads. If lubricants, locking fluid or sealing com- pound are required for a screwed joint this information will be contained in the work description and in “Tight- ening Torques” Where no tightening torque is stated for a joint use the general tightening torques according to the tables below. The tightening torques stated are a guide and the joint does not have to be tightened using a torque wrench. Dimension Tightening Torques Nm lbt.ft M5 6 4,4 M6 10 7,4 M8 25 18,4 M10 50 36,9 M12 80 59,0 M14 140 103,3

7 Tightening torques-protractor (angle) tightening Tightening using both a torque set- ting and a protractor angle requires that first the recommended torque is applied using a torque wrench and then the recommended angle is added according to the protractor scale. Example: a 90° protractor tightening means that the joint is tightened a further 1/4 turn in one operation after the stated tightening torque has been applied. Locknuts Do not re-use lock nuts that have been removed during dismantling as they have reduced service life when re-used – use new nuts when assembling or reinstalling. For lock nuts with a plastic insert such as Nylock ® the tightening torque stated in the table is reduced if the Nylock ® nut has the same head height as a standard hexagonal nut without plastic insert. Reduce the tightening torque by 25% for bolt size 8 mm or larger. Where Nylock ® nuts are higher, or of the same height as a standard hexagonal nut, the tightening torques given in the table apply. Tolerance classes Screws and nuts are divided into different strength classes, the class is indicated by the number on the bolt head. A high number indicates stronger material, for example a bolt marked 10-9 indicates a higher tolerance than one marked 8-8. It is therefore important that bolts removed during the disassembly of a bolted joint must be reinstalled in their original position when assembling the joint. If a bolt must be replaced check in the replacement parts catalogue to make sure the correct bolt is used. Sealants A number of sealants and locking liquids are used on the engines. The agents have varying properties and are used for different types of jointing strengths, operating temperature ranges, resistance to oil and other chemicals and for the different materials and gap sizes in the engines. To ensure service work is correctly carried out it is important that the correct sealant and locking fluid type is used on the joint where the agents are required. In this Volvo Penta Service Manual the user will find that each section where these agents are applied in production states which type was used on the engine. During service operations use the same agent or an alternative from a different manufacturer. Make sure that mating surfaces are dry and free from oil, grease, paint and anti-corrosion agent before app- lying sealant or locking fluid. Always follow the manufacturer’s instructions for use regarding; temperature range, curing time and any other instructions for the product. Tow different basic types of agent are used on the engine and these are: RTV agent (Room temperature vulcanizing). Use for gaskets, sealing gasket joints or coating gaskets. RTV agent is clearly visible when a component has been dismantled; old RTV must be removed before the joint is resealed. The following RTV agents are mentioned in the Ser- vice Manual: Loctite ® 574, Volvo Penta 840879-1, Permatex ® No. 3, Volvo Penta P/N 1161099-5, Perma- tex ® No. 77. Old sealant can be removed using methy- lated spirits in all cases. Anaerobic agents. These agents cure in an absence of air. They are used when two solid parts, for example cast components, are installed face-to-face without a gasket. They are also commonly used to secure plugs, threads in stud bolts, cocks, oil pressure swit- ches and so on. The cured material is glass-like and it is therefore colored to make it visible. Cured anaerobic agents are extremely resistant to solvents and the old agent cannot be removed. When reinstalling the part is carefully degreased and then new sealant is applied. The following anaerobic agents are mentioned in the Service Manual: Loctite ® 572 (white), Loctite ® 241 (blue). NOTE! Loctite® is the registered trademark of Loctite Corpora- tion, Permatex® is the registered trademark of the Permatex Corporation.

8 Presentation The engines are 4 cylinder gasoline engines. All the engines are equipped with freshwater cooling in combination with seawater cooling. The seawater system is powered by a direct drive impeller pump. The thermostat controlled freshwater system is powered by a circulation pump. The engines are manufactured with two different product designations. During 1989 Volvo Penta be- gan designating engines based on their cylinder dis- placement according to the ISO norm 8665. The older product designations of AQ131, AQ151 and AQ171 (where the number provided an approximate indication of output) were withdrawn. The new designation 230 replaced AQ131, 250 replaced AQ151and 251DOHC replaced AQ171. 250, AQ151 and 251DOHC, AQ171 are equipped with an oil cooler. 230, AQ131 has a single carburettor and the others have twin carburettors. The exhaust system has seawater cooled exhaust pipes. 230, AQ131 and 250, AQ151 models have an overhead camshaft while 251DOHC, AQ171 has double overhead camshafts with hydraulic valve lift- ers. 251DOHC, AQ171 is a 16 valve engine. 230, AQ131 and 250, AQ151 models have conventional marine ignition systems while 251DOHC, AQ171 has electronic ignition. The product plate is located on the cylinder block beside the starter motor. The product plate provides the following information; (1) Product designation, i.e. AQ131D (2) Product number, i.e 867902 (3) Serial number (10 digit) (4) Basic engine, serial number Product plate 230, AQ131 250, AQ151 251DOHC, AQ171

VOLVO PENTA AQ131 AQ151 AQ171 Marine Engine Workshop Repair Manual

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