what causes the oil to leak from the opening where the oil stack fits in at the bottom as the engine spins? When the oil level is too full it causes excessive back pressure inside the engine. A leak in the oil supply--anywhere on the machine--requires prompt addressing. It appears that the oil is coming down the blade shaft. Some of those causes are simple to remedy while others are more serious problems that require complicated repairs. I have a craftsman lawn mower that is leaking oil . Oil is collecting on top of the pulleys. â¦ I'm quite confident the gasket is not leaking. I have an MTD 12.5 riding mower that is leaking oil from under the engine. The oil comes out around the bottom of the cylinder, but not at the head â¦ I have a CraftsmanNNN-NN-NNNNpush lawn mower with a ModelNNN-NN-NNNNEager 1 (Techumseh) engine that has a leaking oil seal (bottom seal -- leaking down the shaft onto the â¦ The pressure forces the engine oil to escape from areas such as: the dipstick seal, lower crankshaft seal, o il pan gasket and can cause the head gasket to blow â¦ I am assuming that there is bearing and a gasket where the shaft comes out of the motor. Oil leaking through a lawnmower's air filter has several possible causes. Could this be the seal to the shaft? Report This by Manage My Life. In such a case, turn off the mowerâs engine and wait until it has cooled, to examine the oil chamber for leaks if any. If you're using a push mower, you most likely have bent your crankshaft which will cause oil to leak from the main seal on the bottom of your engine. There is a seal at the bottom of the engine and the top is sealed by a tight fit between the crankshaft and the crankcase. I have a 15-year old Craftsman mower that sometime over the winter started to leak oil. How hard is it to repair at home? the model number is 917.388220 it's a craftsman mulcher â¦ June 20th, 2010. there is a long neck where the oil dipstick goes. Eventual motor failure will occur if the oil level in the mower's crankcase falls too low. Very common problem when you hit a rock or stump, etc. To change the oil in a John Deere mower you typically remove a drain plug from the bottom side of the engine so that the old oil can run out through the drain tube. ... March 18, 2020 March 18, 2020 lawn mower engine leaking oil, lawn mower engine leaks oil, lawn mower engine overfilled with oil, lawn mower engine smokes, oil leak on push mower. Once the engine was hot, it started dripping oil on the mower deck, right at the same place below the oil breather. You'll need to make a thorough inspection of the oil system on your Briggs & Stratton lawnmower. If that cap is not properly replaced, or if the vibrations from the engine loosen it or make it fall off, you will quickly discover an oil leak out of this portion of the engine. If the mower inclines towards a particular side when moving on a sloppy area, there is a likelihood of oil leaking onto the muffler, causing the engine to smoke. Holly Holly September 2005 By far, the most common cause of lawn mower engine oil leaks is an overfull engine oil level. What would cause oil leaking from around the shaft under the motor? This is most likely not worth fixing unless you have an expensive, high quality mower. There is no external orifice on the oil breather, so the oil is not coming from there.