Help! Craftsman 14.5H Briggs & Stratton blowing oil & gas in the oil!

Old 07-28-11, 07:33 AM
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Help! Craftsman 14.5H Briggs & Stratton blowing oil & gas in the oil!

My 10 year old 14.5H Craftsman Mower is in sad shape.

Sunday I mowed a little bit, it was stuttering a bit and smelling a little of oil and so I turned it off and went back half hour later. At that time it refused to start which is unusual since it always fires right up. It turned over but acted flooded and I could smell gas. So I let it sit a while longer and went back another half hour later. When I turned the key, the engine went CLUNK and then nothing happened when I turned the key, just a click. Fuel was leaking out madly from somewhere I could not figure out.

Sad me left it for my friend to look at the next day. He said it started right up but then got really hot right away so he shut it off. He said it might be a blown head gasket or cracked head. He did not notice the BIG fuel leak... but said there was no gas in the oil.

The next day I removed the head and checked the gasket. They were both intact but there was oil inside the head where those springy-things are (forgive me, I'm a girl!). I think that is not good. I removed the carb and checked the fuel inlet which was clean and full of gas. The carb seemed fine but I was afraid to dismantle it, the air filter needs replacing. I could not tell where fuel might have leaked from at that time because the motor was pretty dirty and it seemed that this problem may have started small and then escalated.

Next day (yesterday) I drained the oil - which was full of gas. Not good I know. I refilled with new oil, put everything back together and actually managed to get it to start and run! (major victory on my part!)

HOWEVER, there was a lot of oil blow-by into the manifold (at least what I think is the manifold) and lots of smoke and sizzling. My father in law says that the rings might be bad, the block might be cracked or other dire prophecies that basically mean there is some way that the gas and oil are mixing where they should not. I have someone coming to look at it tonight but I'm wondering if anyone knows if I am on the right track or is it something ridiculously easy to fix? I figure if it costs more then $200 to fix then I should just buy a different one since I can get good used lawnmowers for around $500 locally and a comparable one brand new for $950.

Your thoughts please????


Laura in Michigan (who has many acres to mow all the time...!)
Old 07-28-11, 08:23 AM
Join Date: May 2006
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The main source of gas in the oil comes from the carburetor float sticking or the float valve that it controls leaking. That is a simple fix with just replacing the float and valve with a couple gaskets.

On some engines a fuel pump can cause a similar problem, but usually it's in the carburetor.

That's really the first thing you have to address and get cleaned up since the extra gas in the oil would raise the oil level in the crankcase and account for the blow by. You would get the leak stopped, then run it for a while to burn out the residue.

From that point on you could evaluate your mower to see if there is something else to work on. It may or may not be worth the expense.

First get the carb in good shape, then change the oil before running, check the oil level and see if it stays the same after the fix. This may take care of everything for a few bucks.

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