2015 Yamaha F115B major oil leak

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FISHNFF
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2015 Yamaha F115B major oil leak

Postby FISHNFF » Thu Nov 02, 2017 3:43 pm

After a WOT run of 10-minutes, I slowed to see oil in the water. I shut down the engine--turns out [the source of the oil in the water is from] my 2015 Yamaha F115B engine. I pulled the engine cover and there is oil all over. I checked oil fill, dip stick and filter. All were tight.

I fired up the engine again, and saw oil running down from under the flywheel. I shut down and got a tow.

I called a dealer and was told [the cause of the oil leak is] probably [the failure of] a main seal. I was thinking that or a camshaft seal.

[Give me] any thoughts [you have on the source of the oil leak] while I wait to bring [the engine to a dealer for service] next week.--FISHNFF

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Re: 2015 Yamaha F115B major oil leak

Postby jimh » Thu Nov 02, 2017 8:57 pm

I can give you the following thought that came to me after reading your narrative:

--get the engine into a heated environment so that the flow of oil is made easier;

--remove the cowling and any other internal engine covers that hide the engine block from view;

--clean up all the existing oil that you have found under the flywheel;

--start the engine with a hose adaptor to provide cooling water;

--with strong lighting and a good portable flashlight, make a close visual inspection of the suspected flywheel area and the main bearing seal area to assess those places as sources of the leak.

FISHNFF
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Re: 2015 Yamaha F115B major oil leak

Postby FISHNFF » Fri Nov 03, 2017 2:13 am

Thanks Jim.

Yes, the dealer will (hopefully) tell all. I just wanted to know if anyone has seen this on any similar four-stroke outboard engine. I've found nothing on the internet.

This has got me bothered. I know and hope this is a one-off anomaly. I take this, and most of my boats, all over, including way offshore. Often alone. I always tell my wife that I'll be ok as long as I stay in the boat and the motor is running. This catastrophic failure has me thinking. --FISHNFF

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Re: 2015 Yamaha F115B major oil leak

Postby jimh » Fri Nov 03, 2017 12:44 pm

I agree--losing a lot of lubricating oil from a four-stroke-power-cycle engine is really a worry. Which end of the engine is considered the main seal? The upper seal at the flywheel? Or the lower seal that connects to the drive shaft? You'd think just based on gravity load that the lower seal would be the most likely to have added stress.

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Dutchman
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Re: 2015 Yamaha F115B major oil leak

Postby Dutchman » Fri Nov 03, 2017 1:51 pm

jimh wrote:I agree--losing a lot of lubricating oil from a four-stroke-power-cycle engine is really a worry. Which end of the engine is considered the main seal? The upper seal at the flywheel? Or the lower seal that connects to the drive shaft? You'd think just based on gravity load that the lower seal would be the most likely to have added stress.


Unless you have some kind of blow by and pressurizing the sump area then all seals will be under stress.
For the OP you could do cylinder compression tests which might rule the above out.
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Re: 2015 Yamaha F115B major oil leak

Postby Don SSDD » Fri Nov 03, 2017 3:43 pm

Are the plugs clean? If yes, likely a seal of some kind.
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Re: 2015 Yamaha F115B major oil leak

Postby jimh » Fri Nov 03, 2017 5:35 pm

The pressure that I see being greater on the lower seal is a result of gravity. Gravity is more or less a universal thing, so i don't see how you can ignore gravity's influence.

For the oil to be leaking out from the crankshaft seal at the engine top, there must be some positive pressure on the oil, as it would not tend to rise skyward and come out the top seal; gravity would intervene.

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Re: 2015 Yamaha F115B major oil leak

Postby FISHNFF » Mon Nov 20, 2017 1:58 am

Got the word from the dealer that the main seal blew out and became unseated. Yamaha is replacing it under warranty with a new seal. UT WHY did it go out in the first place? Will it happen again?

Hope to run it after getting it fixed next week. Hmmmmm

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Re: 2015 Yamaha F115B major oil leak

Postby flymo » Mon Nov 20, 2017 7:02 am

I am sure Yamaha will be very interested in why the seal went out as well. It has to be a defective seal, improper installation, or a defect in the casting and machining of the sealing surface. Speaking of the latter, you should make sure the dealer is inspecting those surfaces carefully.

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Re: 2015 Yamaha F115B major oil leak

Postby Phil T » Mon Nov 20, 2017 8:36 am

Given your engine is practically brand new, I would proffer that the failure was a defect in the seal itself or the installation at the factory.

How many hours has it been run to date?

While I would shake my confidence (I am typically solo), I would try to not go too deep down the rabbit hole of doubt.
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Re: 2015 Yamaha F115B major oil leak

Postby FISHNFF » Thu Nov 30, 2017 8:41 pm

Update--Yamaha is replacing the entire block with, of course, new main seal installed. I feel much better, as this would rule out something wrong with the block and not just the seal. I believe this was an anomaly, as I had not seen this failure after a lot of internet searching. [The failure occurred with the engine having a run time of] around 200 hours. I hope to get the boat and motor back next week, and I get to do the break-in again. Will keep you informed. --FISHNFF

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Re: 2015 Yamaha F115B major oil leak

Postby jimh » Fri Dec 01, 2017 9:43 am

Thanks for the update. It is always interesting to hear the ultimate resolution of a problem like this.

Are Yamaha going to replace the whole powerhead with a new, completely-dressed powerhead? Or just replace the block and reuse all other components from your original engine?

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Re: 2015 Yamaha F115B major oil leak

Postby FISHNFF » Thu Dec 07, 2017 9:34 am

I'm not sure if it's just a block or entire complete powerhead.
I'm thinking entire new powerhead. Giving the price of labor, it may be cheaper.

I hope to know very soon. I've been running my 15 Striper in the Bay in the meantime. I missed crabbing in my 18, but luckily had friends and ran with them before the take dried up.

I'll report back when I get her back and start the break-in again.


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