Help with my Craftsman Rider Mower


Old 04-12-08, 09:26 AM
Thread Starter
Join Date: Apr 2008
Posts: 2
Help with my Craftsman Rider Mower

I need some help diagnosing what's wrong with my Craftsman., which I rolled out this morning for the first time this year. I bought it used, but I believe it is about a 2000 year model, possibly a bit older. It has a 16.5HP Kohler engine. Before starting her up I pumped out the oil through the dipstick, refilled it with new, good oil and a few ounces of Marvel Mystery oil. I then filled the empty gas tank with fresh gas, a few ounces of Marvel, and a few ounces of fuel stabilizer. I also cleaned the oil filter. When I last used the mower in November, everything worked fine.

When I started it up there was a copious amount of grey exhaust, I heard a pop that sounded like a gun was fired, and nasty black oil started coming out in a thin stream draining from what I think is the muffler. The exhaust soon became white, but is still coming out in huge quantity.

Anyone have any idea what's wrong/what I need to do to fix it? Should I replace the muffler? Can I replace the muffler myself? The only engine I've ever worked on is an Atomic 4 in an old boat. Thanks.
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Old 04-12-08, 09:53 AM
Join Date: Feb 2008
Location: Western Area
Posts: 94
The muffler is not the problem, check your oil level it may be overfull of oil. Check the oil for fuel contamination and make sure there is no gas in the oil. You may have a blown head gasket causing the problem, oil in the muffler has to be coming from the cylinder and out through the exhaust valve to make it into the muffler.
Old 04-12-08, 11:49 AM
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Join Date: Apr 2008
Posts: 2
There is gas in the oil that's leaking out. Does this establish that there is a blown gasket?
Old 04-12-08, 06:11 PM
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Join Date: Feb 2008
Location: EveryWhere
Posts: 1,263
Nope, You have a problem with the float needle valve inside the carb not fully seating causing fuel to flood into the cylinder past the rings and into the crankcase.

A good carb tear-down and clean might do the trick but I don't go into one myself without replacing the float needle valve, It's not worth taking the chance of a return and un-happy customer.

Good Luck
Old 04-13-08, 12:56 AM
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I agree, and want to add that you should not run the engine any more with this diluted oil in it. I suggest fixing the carb problem, then drain the gassy oil conventionally from the drain plug so that it is all removed, and put in fresh.

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