Section 3 Troubleshooting Check the condition of the oil. Drain the oil into a container - the oil should flow freely. Check the appearance (color) of the oil, and for metal chips or foreign particles. A milky, opaque color denotes the presence of engine coolant in the crankcase oil. Basic Engine Tests Crankcase Vacuum Test A partial vacuum should be present in the crankcase when the engine is operating. Pressure in the crankcase (normally caused by a clogged or improperly assembled breather) can cause oil to be forced out at oil seals, gaskets, or other available spots. Sludge is a natural by-product of combustion; a small accumulation is normal.
Excessive sludge formation could indicate overrich carburetion, weak ignition, overextended oil change intervals or wrong weight or type of oil was used, to name a few. 3 Crankcase vacuum is best measured with either a water manometer or a vacuum gauge (see Section 2). Complete instructions are provided in the kits. NOTE: It is good practice to drain oil at a location away from the workbench. Be sure to allow ample time for complete drainage. Test the crankcase vacuum with the manometer as follows: 1. Insert the stopper/hose into the oil fill hole. Leave the other tube of manometer open to atmosphere. Make sure the shut-off clamp is closed.
Cleaning The Engine After inspecting the external condition of the engine, clean the engine thoroughly before disassembling it. Also clean individual components as the engine is disassembled. Only clean parts can be accurately inspected and gauged for wear or damage. There are many commercially available cleaners that will quickly remove grease, oil, and grime from engine parts. When such a cleaner is used, follow the manufacturer’s instructions and safety precautions carefully . 2. Start the engine and run at no-load full throttle speed (3200 to 3750 RPM). 3. Open the clamp and note the water level in the tube.
The level in the engine side should be a minimum of 10.2 cm (4 in.) above the level in the open side. Make sure all traces of the cleaner are removed before the engine is reassembled and placed into operation. Even small amounts of these cleaners can quickly break down the lubricating properties of engine oil. If the level in the engine side is less than specified (low/no vacuum), or the level in the engine side is lower than the level in the open side (pressure), check for the conditions in the table below. 4. Close the shut-off clamp before stopping the engine. No Crankcase Vacuum/Pressure in Crankcase 3.3 Possible Cause Solution 1. Crankcase breather clogged or inoperative. 2.
Seals and/or gaskets leaking. Loose or improperly torqued fasteners. 3. Piston blowby or leaky valves. (Confirm by inspecting components.) 4. Restricted exhaust. 1. Replace breather assembly (valve cover). 2. Replace all worn or damaged seals and gaskets. Make sure all fasteners are tightened securely. Use appropriate torque values and sequences when necessary. 3. Recondition piston, rings, cylinder bore, valves, and valve guides. 4. Repair/replace restricted muffler/exhaust system.