1973 evinrude 115 hp starting problem

[Fed]

At this point I'd remove the lower unit to eliminate it form the problem.
Any history on the motor, new to you, never cranked over, used to crank over but then stopped, have you checked the lower unit oil?

 

[GREE]

Lower unit is good and everything I know that cause I did that myself I tore all the way into it bc a snap ring broke that held to the clutch dog and so I got into it and replaced it new lower unit oil and the prop spins just fine so I'm positive that's not the problem.

 

[GREE]

And also the motor use to never have a starting problem it had a running problem but I fixed that bc the carbs wasn't synced together. It ran good for awhile then the lower unit only knew rev gear only that was the snap ring that held the sliding pin from the shifter to the clutch dog that snap ring broke that I said before. Then it ran like poop still so I rebuilt the carbs and cleaned the spark plugs off bc there was no idle screws in the carbs so the spark plugs was soaked. Then fuel pump broke on me as I was about the mount it back to the carbs and it broke so I replaced that then it started having this starting issue. Then I noticed the low compression in that one cylinder. Rebuilt starter, new 2 gauge welding leads for battery wire so I know it's getting juice lol haha, refurbished optima battery. And when it did run i didn't hear any knocking in the motor.

 

[GREE]

Jbuote thanks for the advice I took off my flywheel last night and my flywheel wasn't lined up with the crank case at all idk how it must have slipped or idk but right now trying to get the woodruff key out it is stuck in there pretty good lol

 

[interalian]

Flywheel nut torque is critical, as is an intimate fit between the crank taper and the one in the flywheel. If it went off time and the key is still in the crank, it must have torn up the flywheel taper. Pics?

 

[jbuote]

^^^ Yes!! Pics of crankshaft taper, Flywheel taper, and key slot would be GREAT! (Good visual for others too if they find this in the future and it helps them..)
​The taper is most definitely critical, and must be good. If it's not perfect, you could use valve lapping compound on it to get a better fit.. I used Prussian blue on mine to check the tapers when I had mine off. Didn't have to lap it, so I was lucky..

​I for one would be VERY interested to see the pics of what you found if you could post some!

​Glad you found an issue, and I'd bet it takes care of the starting and backfiring issue once fixed..
But! Don't forget... This doesn't address the low compression in one cylinder.. That should be checked into as well.....

 

[mla2ofus]

Just want to throw in: absolutely no lubricant of any kind between the flywheel and crankshaft.
Mike

 

[GREE]

No Title

Here are three pics of the flywheel I'm not with my boat right now but I had the flywheel with me. I don't see any damage on the crank but I stuck in a new woodruff key and it looks like it was sheared bc it doesn't stick out as far as the new key does also with measurement I bought the key from a local parts store and used a micrometer to measure it.

 

[jbuote]

Well......
​Again, I'm NOT an expert, so maybe they'll advise as well, but that looks like quite a bit of scoring in there to me..
​If that were mine, I'd SERIOUSLY consider using valve lapping compound and get a better mating surface between the crankshaft and the flywheel..
I think you'd be surprised at how little imperfections in the surfaces can make a very large impact on how well the flywheel will stay in place, or not stay in place..
(If I recall correctly...)

​Would love to see pics of the shaft when you're at the boat next though..

 

[jbuote]

I bought the key from a local parts store

OOOoooohhhhh....
​I wouldn't recommend using that key then.. The key is one part I personally would NEVER use anything other than OEM factory or factory direct replacement...

​I don't think you can accurately measure what key you need without having an actual and intact key to measure...

 

[GREE]

No Title

Here are the crank shaft pics.

 

[jbuote]

That doesn't look too bad.. I think I'd still use some valve lapping compound though to clean up the inside of the flywheel..
​That way the flywheel gets cleaned up, and anything imperceptible in the crank gets taken car of..
​Then a line of Prussian blue to check the mating surfaces. repeat lapping compound and Prussian blue till I had good contact surfaces.

​Once satisfied, I'd fully clean and degrease both flywheel and shaft so there is nothing there to act as a lubricant, then install to proper torque, run for a little bit, then re-torque.

​That's what I'd do based on your pics, but maybe the real pro's here have better thoughts?

 

[Fed]

1988 Model, check your torque value as it may not be the same.

NB: Key position & compound on the nut.

 

[GREE]

Thank you guys for your help and replying to me. I will get this job done hopefully before this weekend if not I got the weekend at least haha. Thanks guys for the help once again I appreciate everyone who replied.

 

[GREE]

Hello guys so I replaced the key and torqued it down as should, still having the same problem. My dad was told by a boat mechanic to take the lower unit off and it'll identify if there is a bearing out and I done as he said still the same problem I can take all plugs out and it'll spin super fast but when I put them in it is having a super hard time and hard to turn by hand to. I noticed in the spark plug hole that it looks like a lot of carbon build up through out the motor on the head. Where does the exhaust gases go after leaving the cylinder? Could carbon build be on whatever it is that lets it out since it has too much pressure on the cylinder to start and that's my problem?

 

[Fed]

Have a look at the bore down the sparkplug holes.
http://www.ebay.com.au/itm/2M-7mm-A...248852&hash=item1c6b4d6825:g:FgEAAOSwXetZR6B-

 

[GREE]

Okay thank you fed. Could it be a gasket issue? I've also been told it could be bc of the rings or a small crack on the top of the Piston head? I'm thinking about just pulling the head and the side cover off but is one of these gaskets could be the problem and stuff?

 

[GREE]

So I took my head off today and I saw bubbling on the gasket in several spots, lots of carbon building on the Piston, head bolts where beyond rusted, but I didn't see any cracks on the Piston I do plan on cleaning them and inspecting then but initially there were no cracks. Wiggled both Piston 90 psi and 120 psi didn't feel a difference in the wiggle. Should I proceed on taking the by pass cover off and inspecting that to?

 

[interalian]

If you shine a bright flashlight down the side of the piston with the piston at top, you should be able to move the piston around and see the top ring through the gap between the cylinder wall and the piston. Have a peek and report back. (You should see a nice, shiny ring all the way around save a gap either at the very top or very bottom.)

 

[GREE]

Okay thank you sir. Could the head gasket been a problem just curious about that though still?