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Can you damage a motor runiing it with 1 cylinder not firing?

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Old 08-15-2002, 08:58 PM
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Question Can you damage a motor runiing it with 1 cylinder not firing?

It seems the "marine engine specialist" that rebuilt my motors (because they blew them up in the first place) returned the boat to me and one motor did not have 1 plug wire connected. I discovered it today while swapping oil pressure senders. I have abot 20 + hrs on it and would like to know if I could have done any damage.

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Old 08-15-2002, 09:06 PM
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I don't think it would do any damage - But how could you put 20 hrs on an engine and not notice that it was only running on 7 cylinders. It should have been very obvious.
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Old 08-15-2002, 09:12 PM
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Hmmm.... I'm with Tinker, it probably just came loose or you'd a notice sooner. But if not, the 20 hours of gas went somewhere. Might want to change your oil. Are you sure the sender is bad and it's not just thinned out?
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Old 08-15-2002, 09:13 PM
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i dont think it hurt anything, I took delivery of my baja last year, and when they had the timing light hooked up they knocked off a wire, it was hard to notice, hope all goes well Ron with the boat.
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Old 08-15-2002, 09:20 PM
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Tinker & Mach

I did notice the motor was off a little at idle but they are running rich and were hard to start so I thought it was loaded up. With twins it was not noticable when running. There was also no increase in oil level. It was not loose because it snapped on pretty tight.
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Old 08-15-2002, 09:39 PM
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With my original Mercruiser wires, #6 would fall off of both motors every 10 hours or so. Never noticeable except at WOT, and at idle. Even then, you had to listen for it. After figured it out the first time, I could hear it whenever it fell off, but my Dad couldn't ever hear or feel it. Boat was off no more than 150 rpm on top. Shows how 50 hp is only good for a leetle beet.

I would think, though, that extended running with no fire would wash down the cylinder walls with gas and over time might contribute to fuel contamination in the oil.
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Old 08-15-2002, 09:41 PM
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Ken, yes you can damage the motor. You can wash out the rings, score the cylinder and dilute the oil to the point of wiping out a bearing. Obviousely you haven't hurt the bottem end yet so change the oil and do a compression test and hopefully you're lucky. It is also possible that the rings will reseat themselves once that cylinder is firing again. Good Luck!!
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Old 08-15-2002, 09:48 PM
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I once drove a truck thousands of miles with the two front cylinders of a 6 banger just going for a ride. Thats what yours were doing, Just going for a ride. Do change the oil though.
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Old 08-15-2002, 11:29 PM
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The gas in the cylinder would be flushed out with each stroke so it shouldn't wash the cylinder much more than normal operation. I guess I must have a tuned ear because I can sure hear a missed fireing of a cylinder.
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Old 08-15-2002, 11:52 PM
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Ken, (Palerider)

Great signature.
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