Small Engines (Lawn Mowers, etc.): Tecumseh OHV130 Leaks Oil

Question
QUESTION: Eric,
I have a used MTD riding mower with a Tecumseh OHV130 206820D engine.  I have noticed an oil leak at the front of the engine dripping down on to the mounting surface of the mower. I cannot tell where it is coming from other than from where I can't see, so I don't know where to begin. I am confident that with some direction I can repair the engine, but I don't want to start blindly. I downloaded the PDF of the engine and am guessing it is under the clyinder somewhere. Please give me some help on where to start.

ANSWER: Check the valve cover gasket first...they are prone to leaking.  If the valve cover gasket is not leaking then the oil sump/pan gasket maybe the problem.  Replacing the oil sump gasket is a time consuming process as you have to remove the engine and dis-assemble the lower half.

How much oil is leaking?
Eric

---------- FOLLOW-UP ----------

QUESTION: Eric,
It is leaking about 1/4oz from what I can tell. It is enough that it pools around the bottom right (from the front of the engine) and leaks down on top of the drive pulley under the frame. When I start the engine the oil is thrown from the pulley making a mess.

Answer
It could be the oil sump gasket but leaky oil sump gaskets are not real common on Tecumseh engines.  Did you check the valve cover gasket?

The only way to verify the oil sump gasket is the problem is to rule out all other leaks.  Is it possible the lower main seal is leaking?

Below is the Tecumseh L head repair manual.  While it is not the same as the OHV engine repair manual it will provide you an idea on the oil sump gasket repair.

http://www.cpdonline.com/692509.pdf