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Old 23 October 2007, 14:10   #31
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Originally Posted by bernithebiker View Post
Did they say why the spark plug stopped working? Was it the plug itself, or the HT lead, or the electrics higher up the chain?
Hard to tell why the spark plug stopped working. Once the boat was taken out of the water they tried to find out why the engine stopped working. When they removed the engine crowl we saw the engine block was perfored and there was water coming out of it. This means they couldn't do anything anymore with the sparkplug as it has been soaked in the water.

The engine block was send to evinrude for further analysis as they couldn't believe what happend. Indeed a spark plug that stops working is rare. First they thought that some water entered the cylinders via the exhaust pipe but this was soon ruled out. From the wear in the cylinders they concluded that our engine had been running for around 20 hours with only 5 cylinders.


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Originally Posted by bernithebiker View Post
Spark plug failure is pretty rare in my book, unless it has been fouled by something, like say too much oil.

Also, I fail to see why not having one cylinder firing would cause the block to fail spectacularly. Oil is still being pumped around the engine, including to the cylinder that isn't firing, so friction should not be an issue. I know car engines can run with one cylinder out almost indefinitely. The only possible reason I can see is that the cylinder that isn't running is cooler than the others and so unusual thermal stresses are set up between cylinder walls/cooling passages. But the oil and water coolant will help to keep temperature levels reasonably constant.
I was told that the mixture of oil and fuel without firing is wearing out the the cylinders. That wear creates heat and at the end the weakest part of the piston / engine broke and slamed a hole in the engine block.

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If it was me, I would want more information from Evinrude. Why did the spark plug fail (or fail to spark)? And why did this then cause complete block failure? Without knowing this, how can you confidently go out to sea again?

ON various sites/forums, I have heard of many Evinrude problems. Personally I will always buy the most reliable thing I can, be it boat, lawnmower, car, whatever. But especially in safety critical applications like boating. If airplane engines can be made 99.9% reliable then surely boat engines can be too?

For me it's Jap all the way, Honda, Yam, Suzuki. (But I know Mercury/Mariner are good too!)
I know several persons who had very big problems (yall had to be rebuild) with their Yamaha engines. 1 had problems with his 300 HDPI engine and to my knowledge a lot of those engines in europe had problems and I know 3 persons who had big trouble with their Yamaha 250 VMax engine.

So again, don't think there is one brand that can claim to produce 100% reliable engines.

anyhow, the service of my dealer and of evinrude was excellent. Since that problem we have put over 200h on the new engine without any problem.

rgs
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Old 23 October 2007, 18:06   #32
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quote
"I was told that the mixture of oil and fuel without firing is wearing out the the cylinders. That wear creates heat and at the end the weakest part of the piston / engine broke and slamed a hole in the engine block."

That was true . Had you noticed the misfire and got it sorted then it would have been ok , but to be fair not everyone would really pinpoint a rough running motor to one cylinder not firing on a 6cyl .
The excess oil blocks the fine air gaps the engine needs to move freely and overheating and seizure is the result .
Adding extra oil to the fuel can cause similar failures then people think the problem is not enough oil when in fact its too much .
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Old 24 October 2007, 02:57   #33
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I am suprised the sophisticated engine managment system that all Etecs have did not pick up on the fault.

Chris
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Old 24 October 2007, 07:28   #34
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I am suprised the sophisticated engine managment system that all Etecs have did not pick up on the fault.

Chris
Absolutely. Surely if the spark plug not firing can cause such catastrophic failure, then it would be very easy for the engine to detect it and shut down, or go into 'limp home' mode.

I am still suprised that something as simple as one cylinder not firing could destroy the engine.

I used to have a v-twin Ducati that lost all power on one cylinder once. I rode 50 miles like that, no problem, albeit a bit slower than usual!
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Old 24 October 2007, 08:47   #35
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As I said earlier it also happened with the new Suzukis. In their case the engine was running too lean - all in the interests of the environment of course.........
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Old 24 October 2007, 13:22   #36
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I am suprised the sophisticated engine managment system that all Etecs have did not pick up on the fault.

Chris
I would of thought it would too , but aren't we talking about the model before the etec here ?
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Old 24 October 2007, 13:28   #37
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I am still suprised that something as simple as one cylinder not firing could destroy the engine.

I used to have a v-twin Ducati that lost all power on one cylinder once. I rode 50 miles like that, no problem, albeit a bit slower than usual! [/QUOTE]


probably an old air cooled motor with massive tolerances and also a 4 stroke would still cause wear with unburnt fuel washing the oil of the cylinders , but its an old ducatti that probably used more oil than a 2 stroke in the first place
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Old 24 October 2007, 14:26   #38
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I would of thought it would too , but aren't we talking about the model before the etec here ?
Nope, mine is E-Tec.

We discussed the warning / detection issue with the mechanic back than and it appears it's hard to electronically detect a spark-plug who is not working. Don't ask me why.

Even if it was possible to install electronics who can detect it, is it worth installing this knowing that a spark-plug that stops working is very exceptional. What I mean is, they need to install some detection system to monitor the most common problems. If they start installing detection systems for every engine component, the engine would be full of sensors which increases the risk of electronic problems, false alarms…

rgs
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Old 24 October 2007, 14:38   #39
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Originally Posted by ian parkes View Post
I am still suprised that something as simple as one cylinder not firing could destroy the engine.

I used to have a v-twin Ducati that lost all power on one cylinder once. I rode 50 miles like that, no problem, albeit a bit slower than usual!

probably an old air cooled motor with massive tolerances and also a 4 stroke would still cause wear with unburnt fuel washing the oil of the cylinders , but its an old ducatti that probably used more oil than a 2 stroke in the first place [/QUOTE]

Not so old, was late 90's, a 900SS, making about 80hp. But yes, air cooled. Not a reliable bike, but not sure it's tolerances were 'massive'...! By comparison my Yamaha 60hp outboard is 1000cc and makes 60hp.

When you say;

The excess oil blocks the fine air gaps the engine needs to move freely and overheating and seizure is the result .

do you mean, that the excess oil is creating resistance to the piston movement (i.e. between the rings and the cylinder lining) or
do you mean that the excess oil is remaining in the combustion chamber and is being compressed by the piston on it's compression stroke?
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Old 24 October 2007, 14:55   #40
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Anyone know how long it would take the water in a cylinder to cause the problems seaharrier had ?
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