2001 Yamaha F115 4 stroke- main bearings failed

[Bigearl]

Thanks, I intend to mike the journals when I can lay my hands on a micrometer, but I have already used platigage on the big ends and they are perfectly in spec, when I install the new mains I will also test them with plastigage to verify that all those clearances are in spec too.

[Bigearl]

I have miked the crank and it shows original size within the accuracy of my measurements. There is no ovality either. I installed new bearings and used platigage to check clearances which were all in spec. so I assembled the bottom end and all went smoothly. When reinstalling the cam drive sprocket and pickup rotor I noticed my Yamaha shop manual has the pickup rotor upside down compared to my motor. I know I have kept the rotor the same way as it originallyt was but the manual does not agree, has anyone run into this discrepancy?

[capt_toddtt]

I'm new here but have been doing some serious reading catching up. Robert Graham mentioned rod bolt coming back. Does he no longer answer post here? Hope so he really seems to be an expert.

[Misskimo]

Sorry to hijack a thread.
This week I seized my 2000 f-100 . I'm glad I found this thread. It explained the slow death of it, You seamed to catch yours in time or it would have been like mine, I was thinking a oil pump went out. But now I'm thinking a few things happened to result in my motors major heart attack
I do think my boat was too big for my motor . Package deal in 2000. Huews craft 22 foot sea runner hardtop. It was well worked through our short summer here in Alaska . I had a moose and 2 caribou with 5 people in the boat when it blew. It was running fine . On step running about 4700 rpms. Seen some changes in the water that made me slow down thinging it was shallow . Went off step. When through it and opened WOT and all he!! Broke loose. Oil Alarm went off. 2 pistons shut down. I shut it off thinking it was low of oil. Added some without checking oil dew to big wave. Cranked it up . 20 seconds later it seized.
Question
Is it worth rebuilding ?
Im talking with a sells rep about getting a 150 now. But just wondering about rebuilding it and selling it
Thanks. Tony

[minncat1+]

20 hp yamaha year 2000?

I bought this engine new. For eight years it was used very little, certainly less than 20 hours per summer. In fall every year I changed the oil and changed the lower unit oil. For the last three years I used it more about three times a week for four months, usually to run to fishing spots on my lake. (the best smallmouth bass lake ... anywhere)
Suddenly last fall it lost power and began knocking. Took it in. A "mechanic" at a yamaha dealer said it was a spun prop.... total 259$ with labor. Put it back on the lake... nope.... Got prop money back... took it to another mechanic.... One of the bearings on the main crankshaft is toast... (I was there when he took it apart.) Shaft is scored. He is going to take the head off of it to ascertain possible damage.
I have no idea how this could have happened. This engine was never used hard enough to ruin anything. Moisture?
This mechanic says a new crankshaft is needed. Is it?
minncat1+

[99yam40]

which bearing ?

If crank is scored then my thoughts are yes it needs to be replaced

What did they say could have caused it? Lack of lube?

You really do need to start your own thread with all your info