08' Opti - Seized?

[Lunger50]

Hey folks, hoping for a touch of guidance.

Two Saturdays ago, ran a bout a third of a can in seafoam in a full tank of gas. Motor was running fine. Later in the day it would spit and sputter at rpms under 3000, over that it ran fine. Finished the day without issue.

This past weekend, dropped the boat in engine would not start. Bendix pops up but doesn't spin flywheel. Starter is a year old. Through a booster pack on, same thing. Hmmmm....

Try and turn flywheel by hand..nope, doesn't want to move. Remove belt, still doesn't want to turn. I had some issues with this flywheel (worn teeth) hand a machinist buddy of mine rebuild it earlier in the year, hasn't been a problem.

With the belts off, I did manage to turn the flywheel backwards about half a turn. Try and start it again, Bendix engages spins flywheel, then flywheel locks again.

So what am I possibly looking at here? Would like to do some of my own trouble shooting before taking it to a shop.

Pull plugs and see if I can spin it?

Drop lower unit and try and spin it?

Would crap wrapped in the prop cause this?

Any guidance is much appreciated.

[Rip Bass]

Pull the plugs and see if there is any metal on them,there should not be. Then drop the LU and see if the engine will turn.

[billnorman1]

I do not own one. It sounds like something (inside) is not where it is supposed to be, like a piece of a piston or just maybe carbon came off the head and is locking it up. That would be your nicest outcome. Removing the plugs frequently tells the story, if one comes out with the threads and is bent, or covered with molten aluminum specks, there's your trouble.
In neutral prop issues won't stop your motor unless the whole shebang is siezed up down there, but it doesn't hurt to check that too.

If this is a supercharged motor, those have been known to sh*t the bed dragging the powerhead down with them.

[Lunger50]

I'm really leaning towards some crap making its way in the cylinder due to the seafoam. Would explain the rough idle that day.

Strange it ran till the end if that day, then the next day out was locked solid.

If there is metal on my plugs whats the possible diagnosis there?

If there is crude in the cylinder, if I pull the plugs and lube the cylinders should that solve this? Any recommended products for this?

[EuropeanAM]

May I ask "which" Opti you have? Serial Number?

[Lunger50]

May I ask "which" Opti you have? Serial Number?

2008 115 Serial number is one of these two - 1b702134 or OR213574

I should add, the issues I had with the flywheel earlier in the year. Had a bad starter the year previous that wore some teeth down/off the flywheel. This summer I had a machinist buddy of mine take that flywheel off (took a 1200lb torque wrench and ALOT of cursing to get it off). He took it to his shop, heated the ring gear popped it off and machined the broken teeth. That was sometime early July, been fine since.

I'm really leaning to the seafoam dislodging some crud and that's what's jamming. Makes sense with the rough running at rpms under 3000 last it ran, and that it ran until I trailered it and was then locked solid the very next time I launched and tried to start it.

[EuropeanAM]

This would be the 1B702134 number, then.

Did you remove the spark plugs and see if you could turn it through by hand (making sure it's not FLUID locked)?

[Lunger50]

This would be the 1B702134 number, then.

Did you remove the spark plugs and see if you could turn it through by hand (making sure it's not FLUID locked)?

Doing that in about an hour.

Please elaborate on fluid lock?

[billnorman1]

Gases compress. Liquids do not compress. A liquid lock can be unburned gasoline, oil, or water in a cylinder. When the motor goes onto compression stroke, it stops because of liquid. With the plugs out you cannot have a liquid lock.
Odds are you have a much more expensive issue.

[Lunger50]

Plugs out, won't spin. Plugs looked fine

Lower unit off, won't spin.

Penetrating oil will be sprayed in the cylinders over the next couple of days.

What doesn't add up is that whatever is going on seems to have happened while it was on the trailer. What the heck.

[EuropeanAM]

Might get ahold of a small-bore scope and see if you can look in through the spark plug openings.

Did you take the belt off also (to rule out any of the auxillary belt-driven items)?

Definitely strange to occur on the trailer.

[Lunger50]

Yep belts off.

Alternator and compressor? both spin. I cant get the flywheel to budge even a millimeter in either direction, mind you I was trying this using the claw of a hammer wedged on it as I didn't have a big enough socket. I will have a big socket/breaker bar on the weekend

Took a good look under the flywheel to make sure nothing had broken off and was jamming it there

I agree, really odd and I cant wrap my head around that.

[Lunger50]

Is it possible that some water from the cooling system may of leaked into a cylinder. This might explain the rough running and why it seized while sitting on the trailer?

Also read in the service manual that if a poppet valve sticks open this would cause rough idle under 3000 rpm

[Lunger50]

4 days of spraying oil in the cylinders...still wont budge a millimeter in either direction, with a ratchet and breaker bar on the fy wheel nut, just tightening or loosening that nut...ugh.

Looked in the cylinders with a small 3mp camera that connects to my phone. Couldn't see anything obvious, but hard to get a good view of everything as the spark plug holes are offset to the cylinder.

Any other ideas of things I could try before taking this into a shop? Fill the cylinders with transmission fluid? Get a drive shift to fit in directly to the crank and try and turn it there?

Something just isn't adding up here

[EuropeanAM]

Ok... this may seem obvious but I have to ask at this point. Is the STARTER drive gear DOWN (disengaged from the flywheel)?

If so... and if you've removed the gearcase as well to rule out any possibility of it being seized, you're dealing with a rather strange one.

Only other access to look into the cylinders would be to remove the direct injectors (much smaller hole but closer to center of combustion chamber).

[Lunger50]

Yes bendix is down.

Lets for arguments sake say it isn't a cyclinder, what's another possible cause. Something in the crank case/shaft.

Injectors are right there on the back of the block correct? Just to the left of my plugs on this engine?

[lfb6]

You might check the content of the oil lines for safety's sake. It'd be a very strange thing but it's not completely impossible to get something heavvier than oil and not too well lubricating into the oil tank.

[Lunger50]

You might check the content of the oil lines for safety's sake. It'd be a very strange thing but it's not completely impossible to get something heavvier than oil and not too well lubricating into the oil tank.

Not sure how that would cause this issue if being locked solid?

[lfb6]

Some years ago I wasn't aware that someone had poured fresh water into the oil tank of my Optimax 75. 'Lubricating' with water seized the engine quite well after some weeks standing. But this is extremely unlikely, of course.

upper bearing, second and first crankshaft bearing
Attachment 98759Attachment 98760Attachment 98761

[EuropeanAM]

It doesn't take a ton of water in the oil tank to cause that...