yamaha 115 4 stroke

[99yam40]

Re: yamaha 115 4 stroke

bad rings or hole in pistons
will have to disassemble like they said to see what has happened

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

I can see the top of the pistons ....no holes there ... Do i have to take the entire block apart to get to the rings or is it just a matter of pulling the head off

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

geez -- stop with the ethanol stuff already. Ethanol blended fuel does not go bad in the two months, six months or even a year. Ethanol does not run hotter and in fact it burns cooler so ignition timing can be advanced more which is why cars with e-85 capability deliver more power -- but at the cost of higher fuel consumption. Out west you see higher octane fuel which is achieved because it has ethanol in it. Their regular grade fuel is 84 octane. Higher octane prevents detonation, it doesn't make it worse. We routinely store our boats for six months of the year and they run just fine come spring. 44 hours to have an engine eat pistons means something else mechanically was wrong. It wasn't anything to do with ethanol.

it was due to poor quality fuel once the ethanol dropped out the fuel burned hotter because the octane level dropped so low ...

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

geez -- stop with the ethanol stuff already. Ethanol blended fuel does not go bad in the two months, six months or even a year. Ethanol does not run hotter and in fact it burns cooler so ignition timing can be advanced more which is why cars with e-85 capability deliver more power -- but at the cost of higher fuel consumption. Out west you see higher octane fuel which is achieved because it has ethanol in it. Their regular grade fuel is 84 octane. Higher octane prevents detonation, it doesn't make it worse. We routinely store our boats for six months of the year and they run just fine come spring. 44 hours to have an engine eat pistons means something else mechanically was wrong. It wasn't anything to do with ethanol.

it was due to poor quality fuel once the ethanol dropped out the fuel burned hotter because the octane level dropped so low ...

 

[99yam40]

Re: yamaha 115 4 stroke

So what happened to the water and ethanol?
It is what is on the bottom of tank and gets sucked into the fuel system 1st as that is where the pickup tube is located. And the water /ethanol mix does not burn well

Is it possible, can"t say, but I would think it would shut down motor and cause you to have it all cleaned out

So, I would be looking hard for other things also

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

Well should i just let him tear it apart and fix what he says the problem is...compression is just building up in the crankcase and blowing oil out the intake and a whole lot of air comming out the dipstick tube..my wife says just pay the man to fix it but why is it only cylinder 2 and 3 doing it.. I keep thinking it is something else and when he is gonna tear it down it will turn into a 10000 dollar job instead of 2500...

 

[99yam40]

Re: yamaha 115 4 stroke

It is up to you who does the rebuild and finds out what the cause was so it does not happen again.

But I would be leery of someone blowing smoke up you @ss as to what caused those 2 cylinders problems.
You can get opinions from a lot of people, but a Yamaha master tech is the one I would believe the most. Just have to find one in your area and it will take a tear down to look at every thing

 

[Capt Ken]

Re: yamaha 115 4 stroke

As I said before, lean burn didn't cause this problem. Low octane causing predetionation caused the problem. Common problem with the F115. Have gone through several due to this. Engine has no knock sensor to prevent this. Plus it will cost more than $2500 to repair. The last one I did was closer to $4000

 

[99yam40]

Re: yamaha 115 4 stroke

I just would be leery of diagnoses without them opening the motor up to have a good look at the parts

 

[Pas Bon]

Re: yamaha 115 4 stroke

Well should i just let him tear it apart and fix what he says the problem is...compression is just building up in the crankcase and blowing oil out the intake and a whole lot of air comming out the dipstick tube..my wife says just pay the man to fix it but why is it only cylinder 2 and 3 doing it.. I keep thinking it is something else and when he is gonna tear it down it will turn into a 10000 dollar job instead of 2500...

Give Iberia Outboard a call and see what they think.