# 2 cylinder mower -- only one cylinder working



## smokey99 (Jun 12, 2010)

I've got a 2 cylinder riding mower from Craftsman with a B/S engine in it. It started running rough today and after some diagnostics, I found that I could take one spark plug wire off and it ran exactly the same. Looking at the spark plug, it was pretty old (the mower is a hand me down) so I put new ones in. The spark plug for the cylinder that was giving me problems immediately seems to get covered in a light film of oil and it barely runs again.

Oddly enough, if I take the dead cylinder's plug out, the other cylinder begins to run like a champ, but it sprays out oil from the opened plug hole. The second I cover the plug hole again, it begins to sputter and barely idle. Removal of the plug again causes it to run like a champ. 

I suspect something very bad is happening as I don't believe I should be having oil in that cylinder plug area. 

Any direction towards what the issue might be would be helpful. I tried to search for 'oil spark plug' and the search function ignores the word oil so I get a bunch of non-related posts. 

Thanks,
Smokey


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## justin3 (Apr 10, 2007)

Need the model and type off the engine. If its a V-twin, pull the valve cover on the dead cylinder and look at the valve train. If its an Opposed twin, look into a stuck valve.


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## 30yearTech (Sep 14, 2006)

Do what justin3 suggests and you may also want to check for spark on the dead cylinder. It runs better with the plug removed as there is reduced load on the engine. It's a good possibility that the exhaust valve is not operating on the dead cylinder (if your engine is an OHV)


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## smokey99 (Jun 12, 2010)

Engine is an OHV. Will take a look at the valves. The engine is a NUMBER 407777, TYPE NUMBER 0174-E1


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## justin3 (Apr 10, 2007)

Yeah I just replaced heads on 2 407777's the valve guides wiggle there way out and jam the valve closed, resulting in bent push rods. Fix is new pushrods and head(s). However that is just my experiance recently. Mice love to build nests and chew through wires, so since your engine has 2 ignition coils, one might be eaten through resulting in no spark on one cylinder.


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## smokey99 (Jun 12, 2010)

Meant to mention this earlier too. Definitely getting spark in both coils. Even swapped them and same symptoms -- dead cylinder on the same side. Will dig into this more in the morning. Thanks for all the direction everyone.

Great place!


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