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Yamaha F115 Main Crankshaft Seal blown twice - advice?

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stwax

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I have a 2014 Yamaha F115 on a 2014 Avalon Pontoon (24'). Used in a salt water river in Virginia. Engine is well taken care of. Rinsed out after every use. Had impeller and oil changed this past winter. Etc.

I was running boat WOT in July. Alarms went off. Oil behind engine in water. After restart, as long as I stayed below 2K RPMs, alarms would stay off long enough for us to get home. According to mechanic, main crankshaft oil seal below flywheel blew and lost pressure and oil. They repaired it. On my second trip out after repair (water was like glass; smooth ride), I was at WOT for about 8 minutes and the same thing happened. Alarm went off and could see oil slick behind boat. Took it back to shop and they confirmed, the seal they just put in blew. They are a reputable shop. Not trying to overstep or jump to conclusion that it was an improper repair after the first time but, I wonder if there is any advice I can find on here to direct them to what the problem may be.

Is this common for the F115? Is there an underlying problem with pressure causing the oil seal to fail? Any insights are appreciated. Thanks.
 
Not common.

Could be excessive crank case pressure. Could be just bad luck.

On some Yams they use a retainer to keep the upper oil seal in place.
 
Thanks for the quick reply boscoe. Any thoughts on what might cause excessive crank case pressure? As an aside, when running WOT, it runs at just near 6000 RPMs. Always has since new. I assume that is a normal RPM range and acceptable to be at that level.

Is the retainer you mentioned included with the original manufacture of engine or is it an aftermarket piece that can be added?
 
Happened to me today on humboldt bay. Ran wfo a few miles, pulled up to a stop, and it looked like the Exxon Valdez. Got a tow to the dock, and when i got home ,the crank seal had popped up out of its seat. You-tube vid looks like an easy fix , but what would make the seal blow out like that. What kind of crankcase ventilation is on a 2016 F115? Could that be the problem? Only 240 hours on it.
 
Bigbert121164 said:
Happened to me today on humboldt bay. Ran wfo a few miles, pulled up to a stop, and it looked like the Exxon Valdez. Got a tow to the dock, and when i got home ,the crank seal had popped up out of its seat. You-tube vid looks like an easy fix , but what would make the seal blow out like that. What kind of crankcase ventilation is on a 2016 F115? Could that be the problem? Only 240 hours on it.
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I agree. I am in MT and the local boat facility has not seen this before. I can tell u the old seal will not work as we tried that. At WOT it blew again. Pls let’s stay in touch as to the real long term fix. Thxs. John
 
Are you planning to take this in or repair yourself? I would like to know the cause??? The fix seems a bit hookie to me and not long term. I may write Yamaha a letter for action. Thought here
 
Something within the motor might be causing excessive oil pressure or crank case pressure.

A retainer plate could be crafted to physically keep the main oil seal from migrating outward. But this would be a bandaid approach if there is an oil pressure or crank case pressure problem.


retain.png
 
stwax said:
I have a 2014 Yamaha F115 on a 2014 Avalon Pontoon (24'). Used in a salt water river in Virginia. Engine is well taken care of. Rinsed out after every use. Had impeller and oil changed this past winter. Etc.

I was running boat WOT in July. Alarms went off. Oil behind engine in water. After restart, as long as I stayed below 2K RPMs, alarms would stay off long enough for us to get home. According to mechanic, main crankshaft oil seal below flywheel blew and lost pressure and oil. They repaired it. On my second trip out after repair (water was like glass; smooth ride), I was at WOT for about 8 minutes and the same thing happened. Alarm went off and could see oil slick behind boat. Took it back to shop and they confirmed, the seal they just put in blew. They are a reputable shop. Not trying to overstep or jump to conclusion that it was an improper repair after the first time but, I wonder if there is any advice I can find on here to direct them to what the problem may be.

Is this common for the F115? Is there an underlying problem with pressure causing the oil seal to fail? Any insights are appreciated. Thanks.
Click to expand...
Keep operating the motor with a known problem and a loose oil seal might be the least of your problems.
 
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