yamaha 115 4 stroke

[Capt Ken]

Re: yamaha 115 4 stroke

Remove the crankcase vent line that runs from the valve cover to the air cleaner and see if its blowing oil vapor out. Bottom line, compression is blowing past the rings and pressurizing the crankcase. Pull the head.

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

no smoke at all at start up and it is not making oil at all it is fresh clean oil coming out the intake and no gas smell what so ever in the oil still waiting for the second opinion. he said he will inspect it with a camera and do compression and leakdown on it

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

well got the bad news. the shop told me that the cylinders were so tight that the pistons had no room for expansion when they heated up and it also burned up from this ethanol crap in the fuel burned too hot and with only 44 hours on the motor it was not broke in yet. so now i have to overhaul the motor and i just got to put it in the water twice since i got it but i guess that boat really does mean (break out another thousand) well 2500 to be exact for a new overhaul

 

[Capt Ken]

Re: yamaha 115 4 stroke

Run quickly to someone else. That is the biggest line of bull crap I've ever heard. Ethanol does not create a hotter fuel burn and does not cause pistons to expand faster than cylinder walls. It amazes me on the stories shops tell customers to get their money. This one is going to rate toward the top. Being its obvious they have no idea what the problem is, they sure are not going to be able to repair it.
Hmmm, wonder why your car isn't having the same problem since all vehicles run on 10 percent ethanol.

 

[Capt Ken]

Re: yamaha 115 4 stroke

Had to phone my Yamaha tech rep and tell him that one. Said that was the first he has ever heard of that one. He also said to run away and agreeded that the engine would probably need rebuilding but if the mechanic doesn't know what is causing the problem, they can't fix it.
He commented on, how did the cylinders get too tight? Did the cylinder liners shrink? Did the pistons swell? We then made bets on what the problem really is.

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

well he said it was detination and the boat sat for a couple months before i bought it so the fuel seperation that apperently happened in the tank and it sucked up that straight ethanol and burned it up. the pistons swole and left pieces of the piston skirts in the cylinder walls said he had to get the cylinders bored to .25 and put new pistons. and the plugs looked like they were dipped in asphault

 

[99yam40]

Re: yamaha 115 4 stroke

Moisture /water is absorbed by the ethanol and then it separates out of the fuel. water and ethanol do not burn well if they burn at all.
the remaining fuel is low octane fuel as the ethanol is one of the octane enhancers.
So you end up with very low octane fuel that burns too fast and detonates as the piston is still heading up on the compression stroke.

I still wonder if these guys know what is going on, but it is up to you as to who you want to fix it

 

[Capt Ken]

Re: yamaha 115 4 stroke

Hmmm, I think I said pre-detonation from low octane in an earlier post. Ethanol doesn't phase separate unless water is absorbed and the mixture will not burn.

 

[Pas Bon]

Re: yamaha 115 4 stroke

A boat sitting for a few months is not the cause, hell if that was the case we would hear the same story all the time! Many boats sit for months! Somebody is getting swindled!!!

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

well im really at wits end here cause my brother in law is a diesel mechanic and he asked me all the same stuff he wants to pull the head and try to find exactly what caused the problem cause he has never heard of ethanol burning a motor like that and he has had alot of different motors. and all yamaha told my wife was there is no recalls on that series of motor so they cant help me. i think ill have to call them and tell them what was told to me by the mechanic and see what they say because with only 44 hours on this motor there should be no reason for a complete rebuild ...and when i ran it and all this started i had just put 20 gallons of 89 octane in it and only burned about 11 gals that day....

 

[Pas Bon]

Re: yamaha 115 4 stroke

OOGA,

There is a certified Yamaha shop down the road from you in New Iberia on HWY 90, ( Iberia Outboard) I have dealt with them before and I think they would shoot you straight.

 

[Capt Ken]

Re: yamaha 115 4 stroke

There is no recall on that motor and Yamaha will not listen to any mechanic unless they are certified by Yamaha. It will take a teardown and then the area rep will have to look at it to see if there is any factory defect. If no defect is found, then you have a bill to pay and a box of parts to take home.
Those mechanics told you the pistons was too tight and the head hasn't been removed? You are going to have get away from those shadetree mechanics

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

i just called my mechanic he said it was due to the ethanol separation and bad fuel so it had a higher detonation temp and high compression which caused detonation. he is not a yamaha dealer he just does the work for a dealer. but he comes highly recommended by quite a few ppl in the area. and he is not trying to screw me like redmonds was they wanted over 5 grand to overhaul it and hes only charging 2500 for all parts and labor and a warranty

 

[Capt Ken]

Re: yamaha 115 4 stroke

$4500-$5000 is normal for a rebuild on that engine. If he is doing it for $2500, then he is short cutting something. I know, I've rebuilt them and if he is not a Yamaha tech, he doesn't have the required tools needed nor access to the parts. Warranty from someone working on the side is only good as long as you can find him. If that engine tanks after the rebuild, he will not have the resources to rebuild it again.

I doubt seriously that he is a trained or experienced Yamaha tech with the answer he gave you.

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

he does the warranty work for gulf coast boats when they are too backed up mostly comercial work though

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

ok guys here is another ? about this motor how much can you bore this motor out. the only size pistons i have seen is .25 and .50 not too sure if i should just go with the .50 or not and how much would that increase h.p. with .25 or .50

 

[OOGA BOOGA]

Re: yamaha 115 4 stroke

ok guys here is another ? about this motor how much can you bore this motor out. the only size pistons i have seen is .25 and .50 not too sure if i should just go with the .50 or not and how much would that increase h.p. with .25 or .50

recent things i just tried to push 100psi. into each cylinder at tdc and my findings are #2 and #3 cylinder is just blowing all the air right out of the oil dip stick hole. so i guess this would constitute an over haul.. any advice would be greatly appreciated

 

[Silvertip]

Re: yamaha 115 4 stroke

well he said it was detination and the boat sat for a couple months before i bought it so the fuel seperation that apperently happened in the tank and it sucked up that straight ethanol and burned it up. the pistons swole and left pieces of the piston skirts in the cylinder walls said he had to get the cylinders bored to .25 and put new pistons. and the plugs looked like they were dipped in asphault

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.

 

[Capt Ken]

Re: yamaha 115 4 stroke

You will gain no extra HP so you can forget that. The sizes from Yamaha is 25 mm and 50 mm. Not .025 or .050. Disassemble engine and see what you have before making any decisions.

 

[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.

that is only what the mechanic is telling me.. I know nothing about all of this .. And i do not know how to work on these four strokes or any outboard for that matter so if i did take it apart i would not know what i was even looking for...he told me 2500 bucks and he will go through the entire motor top to bottom ... Plus yamaha will not deal with me at all the are a bunch of pricks over there two different shops say the same thing and have called yamaha so have i and yamaha say the same thing each time "oh well sorry to hear it but there is no recall on any part for that model motor so you are on your own"....WHAT ELSE DO YOU THINK COULD BE MAKING THE AIR BLOW BY THE PISTONS LIKE THAT.