Lawn Tractor: 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 a problem with your O-ring. To replace the O-ring, start by removing the air filter, the housing, and the blower motor bolts, and detaching the oil drain tube. Lift the blower housing off, and remove the oil dipstick tube. By using a small pick or screwdriver, remove the O-ring at the bottom of the tube and clean the surface. Now you can re-install the blower housing, oil drain tube, air filter and housing.

The gasket creates a seal between two joining pieces, keeping fluids from leaking out. If the gasket is damaged, it may result in an oil leak. If you notice any oil leaking from a gasket, it will need to be replaced. If your tractor has a damaged valve cover gasket, simply remove the bolts holding the valve cover in place, clean both surface areas with parts cleaner and a soft brush, and re-install the new valve cover gasket. Make sure to tighten it down to 60 inch-pounds. For a leaky head gasket, start by removing the air filter, blower housing, and oil drain tube from the blower housing. Next, disconnect the spark plug wire and spark plug, remove the exhaust manifold and carburetor from the cylinder head, and remove the valve cover. You can loosen the rocker arms and slide them to the side rather than removing the rocker arms entirely. Next remove the push rods. You may have to rotate the flywheel to get both valves closed. Now you can remove the cylinder head mounting bolts. Remove the cylinder head, pull off the old gasket, and clean off both surfaces on the engine block and cylinder head. At this point you can install the new head gasket and cylinder head. To avoid warping the cylinder head, torque the head bolts to 150 inch-pounds in an alternating specific pattern (check owner’s manual for exact specifications and procedure if needed). Then, re-torque to 250 inch-pounds. Insert the push rods, and make sure the valve cap is still in place. Rotate the rocker arm back in place and tighten the rocker arm bolt. Make sure both rocker arms are loose and reset the gap between the valve cover caps and the rocker arms. The intake should be 3 to 5 thousandths of an inch and the exhaust should be 5 to 7 thousandths of an inch. With the gap set, tighten the pivot nut set screws and replace the valve cover gasket. You will want to torque the valve cover down to 60 inch-pounds. At this time, you can re-install the exhaust manifold, carburetor, spark plug, and spark plug wire. Reattach the blower housing, oil drain tube, and air filter.

Your lawn tractor’s oil filter prevents dirt and debris from entering the engine, protecting it from damage. If the oil filter is leaking, simply remove it, and clean the surface where it mounts to on the engine. Be careful not to scratch or damage this area as you want a tight seal. Now you can replace it with a new filter. Be sure to use some motor oil to lubricate the seal on the oil filter by dipping your finger in the oil and running it around the seal. Attach the new oil filter hand tight, start the engine and check for leaks.

Oil seals keep the oil sealed in around the crankshaft to prevent leakage. Check around the crankshaft seals for leaks, and if you do notice one, the seal must be replaced. You will have to pull the engine for this. Start by draining the oil then disengage the spark plug wire. Remove the drain plug to drain the oil. It is best to drain oil when the engine is still 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, which is usually located underneath the carburetor. Locate the screw that holds the throttle in place and use a screwdriver to remove the throttle linkage cable. Next, disconnect the starter wires, and locate the bolts that secure the base of the engine to the mower house. Place a wrench onto each bolt and one on the nut underneath the mower house to ensure the bolt does not spin once you remove the nut. Be sure to unscrew the nuts from all the bolts underneath the mower house. Next, remove the drive belt by tilting the engine forward and pulling the drive belt from the crankshaft pulley. Now you can remove the engine. 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. You can now re-install the engine in reverse order of removal instructions. If your issue is with the top crankshaft seal only, you will not need to remove the engine from the lawn tractor. You will have to remove any engine blower housing, as well as the flywheel to gain access to the top seal. You can remove it with a seal puller and install a new seal, the reinstall the flywheel. Loosen the bolts on the ignition module and reset the gap between the flywheel magnets and the ignition module by placing the correct spacer (or a business card) between the flywheel magnets and the ignition module. The magnets will pull the module tight, and you can then tighten the ignition module bolts. Finally, re-install the blower housing.

The oil dipstick tube is where you can find your lawn tractor’s dipstick. It is also where you add oil to the engine. These tubes, and their seals, can deteriorate over time. This can result in oil leaking from your tractor. To change these tubes, remove the air filter and air filter housing. Next remove the bolts holding in the blower housing and detach the oil drain tube and the blower housing. Remove the oil dipstick tube (you may have to remove bolts on the dipstick tube, depending on your model, whereas some just lift out). Next, apply oil to the end and the seal of the new dipstick tube. Clean the inside of the entrance point on the engine, then insert a new dipstick tube. Now you can re-install the blower housing, oil drain tube, and the air filter with its housing.

The covers protect moving parts and keep the oil inside the engine. If you see oil leaking from a cover, you will need to replace that cover. For valve covers, remove the valve cover bolts, and clean the contact area on the cylinder head. Now you can install a new gasket and cover, and bolt it back down. You will want to tighten it to 60 inch-pounds. For crank case covers, start by draining the oil, then disengage the spark plug wire. Simply pull away 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 also captures many 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. Next, disconnect the starter wires and locate the bolts that secure the base of the engine to the mower house. Place a wrench onto each bolt and one on the nut underneath the mower house. This will ensure the bolt does not spin once you remove the nut. Be sure to unscrew the nuts from all the bolts underneath the mower house. Now remove the drive belt by tilting the engine forward, at which point you can pull the drive belt from the pulley. The belt is found on the crankshaft beneath the engine. Remove the engine. With the engine on a bench, start by removing the crank case cover bolts, and then remove the crank case. Remove the old gasket and clean the surface where the gasket makes contact on both sides. Install the new gasket and tighten the bolts down to the manufacturer’s specifications. Add engine oil to the proper level and re-install the engine in reverse order that you removed it.