Section 3 Troubleshooting Engine Overheats 1. Radiator, and/or cooling system components clogged, restricted, or leaking. 2. Excessive engine load. 3. Low crankcase oil level. 4. Low cooling system fluid level. 5. High crankcase oil level. 6. Lean fuel mixture. 7. Fan belt failed/off. 8. Cooling fan broken. 9. Water pump belt failed/broken. 10. Water pump malfunction. 11. Faulty carburetor. Engine Loses or Uses Coolant 1. Overheating-See "Engine Overheats". 2. External leakage-from a joint connection, or a component of the cooling system. 3. Internal leakage-from a head gasket, or cooling system water jacket (passage) leak.
External Engine Inspection Before cleaning or disassembling the engine, make a thorough inspection of its external appearance and condition. This inspection can give clues to what might be found inside the engine (and the cause) when it is disassembled. Engine Knocks 1. Excessive engine load. 2. Low crankcase oil level. 3. Old or improper fuel. 4. Internal wear or damage. 5. Hydraulic lifter malfunction. 6. Quality of fuel. 7. Incorrect grade of oil. Check for buildup of dirt and debris on the radiator, crankcase, cooling system components, and other external surfaces. Dirt or debris on these areas are causes of higher operating temperatures and overheating.
Check for obvious fuel, oil, and coolant leaks, or damaged components. Excessive oil leakage can indicate a clogged or improperly assembled breather, worn or damaged seals and gaskets, or loose or improperly torqued fasteners. Coolant leaks can cause higher operating temperatures and overheating. Engine Loses Power 1. Low crankcase oil level. 2. High crankcase oil level. 3. Dirty air cleaner element. 4. Dirt or water in the fuel system. 5. Excessive engine load. 6. Engine overheated. (See "Engine Overheats") 7. Faulty spark plugs. 8. Low compression. 9. Exhaust restriction. 10. Low battery. 11. Incorrect governor setting.
Check the air cleaner assembly/components for damage or indications of leakage. Check the air cleaner element and inner element. Look for holes, tears, cracked/damaged sealing surfaces, or other damage that could allow unfiltered air into the engine. Also note if the elements are dirty or clogged. These could indicate that the engine has been underserviced. Engine Uses Excessive Amount Of Oil 1. Incorrect oil viscosity/type. 2. Clogged or improperly assembled breather. 3. Breather reed broken. 4. Worn or broken piston rings. 5. Worn cylinder bore. 6. Worn valve stems or valve guides. 7. Crankcase overfilled. 8. Blow head gasket/overtightened. Check the carburetor throat for dirt.
Dirt in the throat is further indication that the air cleaner is not functioning properly. Check the oil level. Note if the oil level is within the operating range on the dipstick, or if it is low or overfilled. Oil Leaks from Oil Seals, Gaskets 1. Crankcase breather is clogged or inoperative. 2. Breather read broken. 3. Loose or improperly torqued fasteners. 4. Piston blowby or leaky valves. 5. Restricted exhaust. Check the coolant level within the reservoir and in the radiator. A low or improperly filled cooling system can cause overheating, excessive fuel consumption, and a lack of power. 3.2