You talk about a mess…yes this is one mess maker for sure. You turn the key and start your riding lawn mower up and then spots of oil appear all over your deck and the ground. But what could be causing this?
Well, there are a few things that can cause this. The more common one is the crankshaft oil seal at the bottom of the engine. To check this, a mirror and a flashlight are helpful to be able to see if it is leaking. Oil will normally pool in the drive pulley that is connected to the bottom of the crankshaft. When the pulley starts to turn during starting, the oil is centrifugally slung out of it and spews everywhere.
If the leak is not there, you can move onto the oil drain plug. It could be a square drive plug in the bottom of the crankcase or a twist lock style with a cap on it. These have a tendency to unscrew over time and loosen up. Check them for tightness.
Next check the crankcase seal itself. There is a seal between the two crankcase parts that must be intact and tight to prevent oil from leaking. If that is good it is onto the oil filter. Make sure that it is not leaking as well.
Another possibility is the valve cover gaskets or the cylinder heads themselves. So check them to be sure that they are not leaking.
When you find the source of the leak, contact a riding lawn mower repair professional on our locations page for assistance.