Engine: Leaks Oil

O-rings act as oil seals on stationary parts. If your oil dipstick tube is leaking from the bottom, chances are it’s just your O ring. Depending on your engine it is just a matter of pulling the tube out. There may be a bolt holding it down to the engine or housing, depending on the piece of equipment you’re working on. Once the tube is off, remove the O-ring with a small screwdriver or a pick, clean the surfaces, and install a new O-ring. Finally, reinstall the tube back onto the engine.

The gasket creates a seal between two joining pieces, keeping fluids from leaking out of these joints. Inspect the engine for an oil leak; if you notice any oil leaking from a gasket it will need to be replaced. For a valve cover gasket, simply remove the bolts holding the valve cover in place, in an alternating pattern to keep the valve cover from warping. Clean both surface areas, install a new valve cover gasket, and tighten down in an alternating pattern to manufacturer specs, to perform a tight seal and prevent warping of the cover. For a leaky head gasket, start by removing the air filter assembly. Next, remove the spark plug wire and spark plug. Remove the exhaust manifold and carburetor from the cylinder head, disconnecting the linkages and fuel line from the carburetor, and then remove the valve cover in an alternating pattern to prevent warping. Loosen the rocker arms and slide them over, you do not have to remove the rocker arms. Next remove the push rods. Do not mix them up. You may have to rotate the flywheel to get both valves closed. Remove the cylinder head-mounting bolts in an alternating pattern to prevent warping of the cylinder head. Remove the cylinder head and pull off the old gasket, and clean off both surfaces on the engine block and cylinder head. Install the new head gasket and the cylinder head. To avoid warping the cylinder head, torque the head bolts in an alternating pattern to manufacturer specs. Next, reinsert the push rods, then rotate the rocker arm back in place and hand tighten the pivots down, then set the gap between the valve tip and rocker arm. They should be 3 to 5 thousandths of an inch. Reinstall the jam nuts and tighten down while holding the pivot stationary. Reinstall exhaust manifold and carburetor. Hook the linkage and fuel line back up, then reinstall the spark plug and attach the spark plug wire. Reattach blower housing, oil drain tube, and air filter assembly. For crank case cover gaskets, start by draining the oil then disengage the spark plug wire. Pull away the drain plug and drain the oil. It is best to drain oil when the engine is slightly warm. This enables oil to flow faster than when it is cold. Warm oil also captures more contaminants than cold oil, which helps to cleanse the engine. Next, drain the gas and remove the fuel line at the carburetor. Remove the throttle linkage, usually located underneath the carburetor. Locate the screw that holds the throttle in place. Use a screwdriver to remove the throttle linkage cable. Locate the bolts that secure the base of the engine to the equipment you’re working on. Place a wrench onto each bolt and one on the nut underneath it. This will ensure the bolt does not spin while you’re removing the nut. Next, remove the engine. With the engine on a bench, start by removing the crank case cover bolts, and remove the crank case. You may have to wiggle it off and tap it with a rubber mallet. Remove the old gasket and clean the surface where the gasket makes contact on both sides. Install new gasket and tighten the bolts down to manufacturer specs. Add engine oil to the proper level and reinstall the engine back into your equipment. Reinstall the carburetor, hooking the carburetor linkage back up with the fuel lines, then reinstall the air filter assembly. Reattach the muffler and reinstall the spark plug, then add oil.

Oil seals keep the oil sealed in around the crankshaft to prevent leakage. Check around the crankshaft seals for leaks. If you notice a leak, it must be replaced. Remove the drain plug to drain the oil. It is best to drain oil when the engine is slightly warm. This enables oil to flow faster than when it is cold. Warm oil captures more contaminants, which helps to cleanse the engine. Next, drain the gas and remove the fuel line at the carburetor. Remove the throttle linkage, usually located underneath the carburetor. Locate the screw that holds the throttle in place. Use a screwdriver to remove the throttle linkage cable. For the bottom crankshaft seal, pull the old seal out by using a seal puller. Clean the inside surface, being careful not to scratch it, then install the new seal by tapping it evenly into place. For the top crankshaft seal, you will have to remove the engine blower housing and the flywheel to gain access to the top seal. Remove with a seal puller and install new seal, reinstalling the flywheel. Loosen bolts on ignition module and reset the gap between the flywheel magnets and ignition module by placing the correct spacer or a business card in between the flywheel magnets and ignition module. Rotate the flywheel to line the magnets up with the module. The magnets will then pull the module into place, and then tighten the ignition module bolts. Reinstall the blower housing. Add oil back into the engine before starting. Another method of changing an oil seal is to use a 1/8 bit to drill a hole into the oil seal, then insert a small screw. Next, use pliers to pull on the screw to remove the old seal. Apply a thin layer of oil to the outside of the new seal, then fully seat the new seal inside the engine block. Use a socket big enough to make contact with the oil seal or a piece of plastic pipe and tap it evenly into place with a mallet.

If the cap on the crankcase where you add oil is leaking, simply replace the cap.

If your engine has an oil tube and it is leaking, remove it by pulling it out and inserting a new tube. There might be a bolt holding it in place that you will need to remove and reinstall.

The job of the piston ring is to provide a seal between the piston and the cylinder wall, creating a seal for compression as well as keeping oil out of combustion chamber. When these rings become worn over time, oil can blow past the rings, entering the combustion chamber and creating blue smoke. A compression test will tell you if you have low compression, indicating the rings are bad. Perform a compression test and note the reading, then do a wet compression test by adding a little oil into the cylinder. The oil takes up the gap between the rings and the cylinder wall, increasing compression. If the compression increases in the wet test, this will confirm the rings are bad. After you have determined the rings are bad, start by draining all fluids. Remove the air filter and the air filter housing. Next, remove the spark plug wire and spark plug. Remove the muffler and carburetor from the cylinder head, disconnecting the linkages and the fuel line from the carburetor. Remove engine mounts and the engine from the unit, and place onto a bench or nearby surface. Pull the valve cover off. Rotate the piston to the bottom, loosen the rocker arm nuts, and then slide the rockers over and remove the push rods. Do not mix up the push rods. Remove all the bolts holding the cylinder head to the engine block in an alternating pattern, to prevent warping the cylinder head. With the cylinder head off, remove the old head gasket. Clean both surfaces of the engine block and cylinder head. You do not want to damage this area, as you want a tight seal. Next remove the crank case bolts, and wiggle or tap it off lightly with a hammer, and punch where ever you can make contact on the case. There may even be a key way on the crankshaft that will have to be removed as well, though all models will vary. Remove camshaft simply by pulling it out. Remove camshaft tappets, connecting rod bolts, and the bottom part of the rod bearing. Rotate the crankshaft to the top, then reach in and push the piston out with your fingers. Clean all parts you plan to reuse with parts cleaner and dry thoroughly. Install new rings onto the piston, positioning the ring gaps 1/3 of the way around the ring from each other to prevent blow by. Make sure the oil ring is on the bottom. Using a piston ring installer, line up everything and gently tap the piston into the cylinder. Lubricate the cylinder with fresh motor oil beforehand. All bolts must be torqued to manufacturer specs. With the piston at top dead center, making contact with the crankshaft, rotate together by pushing down on the piston so you can reattach the connecting rod bearing. They only go in one way. Lubricate the camshaft tappets and reinstall. Next, install the camshaft by making sure the timing marks are in line. Lubricate all moving parts with motor oil or white grease first. Reinstall the crank case cover with a new gasket and tighten down to the manufacturer’s specs. Reinstall the cylinder head with a new gasket and tighten the bolts in an alternating pattern to the manufacturer’s specs to prevent warping of the cylinder head. Reinstall connecting rods, sliding the rocker arms back into place. Set the gap between the rocker arm and valve by adjusting the pivot. The gap should be 3 to 5 thousandths of an inch. Tighten the jam nut down while holding the pivot stationary to prevent movement. Reinstall the cover with a new gasket and tighten the bolts in an alternating pattern to prevent warping of the cover. Reinstall the engine back into the unit. Reattach the carburetor, hooking up the linkages and re-attaching the fuel line. Reinstall the air filter housing and filter, as well as the muffler.

Covers protect moving parts from dirt and debris and keep the oil inside the engine. If you see oil leaking from a cover, replace that cover. For valve covers, remove the valve cover bolts, clean the contact area on the cylinder head, install a new gasket and cover, then bolt it back down in an alternating pattern to manufacturer specs to prevent warping.