Motor damaged?

[Kurt505]

I run a 2 stroke outboard, yesterday I was cruising across the lake, everything was fine, then my motor got slower and slower until it shut off (about a 5 second process). After I lifted the motor to make sure there wasn’t a rat nest of line or weeds on the prop I tried starting it up again. First couple times it wouldn’t turn over, then it turned over and fired up so I slowly idled about 200yds to where I was going to fish. While I was trolling with the electric motor I opened up my oil tank/battery compartment and noticed my oil tank moved and my oil line was pinched, restricting about 90% of the oil supply.

I moved the oil tank and straightend out the line. I started out cruising at 1/2 throttle, then 3/4 throttle, then wide open, it ran fine after that. Did I luck out and avoid damage or is there something I should look for?

[jungleboy]

I run a 2 stroke outboard, yesterday I was cruising across the lake, everything was fine, then my motor got slower and slower until it shut off (about a 5 second process). After I lifted the motor to make sure there wasn’t a rat nest of line or weeds on the prop I tried starting it up again. First couple times it wouldn’t turn over, then it turned over and fired up so I slowly idled about 200yds to where I was going to fish. While I was trolling with the electric motor I opened up my oil tank/battery compartment and noticed my oil tank moved and my oil line was pinched, restricting about 90% of the oil supply.

I moved the oil tank and straightend out the line. I started out cruising at 1/2 throttle, then 3/4 throttle, then wide open, it ran fine after that. Did I luck out and avoid damage or is there something I should look for?


If it's running fine you are likely lucky newer 2 strokes rune pretty lean so if you didn't force anything you might be alright. This is why I never trusted oil injection on a two stroke and preferred to mix the fuel manually .
I had an old (1958) Evinrude I seized up on the lake (tried to save a buck with regular 2 stroke oil.).After it cooled down it freed up and I made sure to run marine 2 stroke oil after that and it ran fine for years after that, probably still going .

[Kurt505]

If it's running fine you are likely lucky newer 2 strokes rune pretty lean so if you didn't force anything you might be alright. This is why I never trusted oil injection on a two stroke and preferred to mix the fuel manually .
I had an old (1958) Evinrude I seized up on the lake (tried to save a buck with regular 2 stroke oil.).After it cooled down it freed up and I made sure to run marine 2 stroke oil after that and it ran fine for years after that, probably still going .

Thanks man, that gives me a sense of relief. I’m going to try and get out for a rip one day soon on a popular lake just to see if all is good (it should be), that way if it breaks down I’ll be more likely to get a tow back to shore, lol.

[MooseRiverTrapper]

Your fine. Either seized up or not.

[Iceman80]

Plug the spark plugs and see what they look like. You’ll see evidence of top end damage if there is any. Extreme cases the electrode will be bent or full of debris.


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[Kurt505]

Plug the spark plugs and see what they look like. You’ll see evidence of top end damage if there is any. Extreme cases the electrode will be bent or full of debris.


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I guess that should have been the first thing I checked, I’m going to check it out right now.



Plugs are good. Bottom 2 are a milk chocolate brown, top 2 are a dark chocolate brown. No white or debris.

[Fishwhere]

I had something similar to this happen to me and i thought my motor was overheating and needing to cool down. All it turned out to be was my gas hose connection getting pinched - sounds similar.

[Dean2]

I doubt you did any damage. Depending on make and age it easily could have a shut off if the oil gets too lean. My 150 HP Suzuki two stroke has that feature. Most of the two strokes also had temperature shut down, even if it doesn't have oil monitoring, and too little oil will raise the running temp enough to cause that to shut off the motor.

You said the top of the pistons and plugs look good so most likely you didn't do any damage. Top of piston will almost always show damage before the bearings or rings have a problem.

[Sooner]

So my dad is 83 and getting forgetful. During the winter he put reg gas in the leaf blower instead of mixed even though I had each jug marked with where they go. He did this a few times and each time it slowed to a stop when the reg gas took over. I would see the wrong color gas in, take it home, drain and fill with mixed.

Only now does it blow a bit of blue when it starts and until it is warm. He did damage the piston walls running it dry those times.


You had a one time incident and caught it. I doubt you will see any issues in long term damages. Got lucky.

[bigtuna81]

To me it sounds like the motor had a built in safety mode.

[Tfng]

It’s damaged. How bad is anyone’s guess. Could run for twenty years or pile up next week. It seized due to lack of lubrication so there’s got to be damage it may be slight but it’s there.

The flecks of aluminum on a spark plug can be quite small, have a really good look in good lighting.

I would test the compression.

[YeeHaw]

Only way to know for sure is a leak down and compression test

[Kurt505]

Only way to know for sure is a leak down and compression test

What’s a leak down?

[Dean2]

What’s a leak down?

Put positive pressure into the cylinder and see how long it takes to drop off. Usually on a gasser you pump it up to 40 PSI (screws into the plug hole) and then watch the drop on the Gauge. Valves need to be closed or in the case of a two stroke, piston needs to be above exhaust and intake ports. You are looking for how much pressure is getting by the rings over how long, tells you if the rings are worn or the walls are scored.

[Kurt505]

Well I have a compression tester, I can start there I guess.

[Dean2]

Well I have a compression tester, I can start there I guess.

You don't need to do both anyhow, compression test is just as good as a leak down, just the reverse. Compression the piston builds the pressure, ;leak down you pump the pressure into the cylinder. Only thing a leak down might spot that may not show as good on a compression test is minor scoring, major scoring will show on either. On a 4 stroke the leak down will also spot bad valves or valve stems, gaskets.

If the cylinders build good and even compression there can't be much wrong with the rings or the walls. I really doubt you will have any issues but it is worth doing if you have a compression tester, it only takes a few minutes and it will easy your mind.

[jungleboy]

Are you willing to spend the money to have it in for a rebuild? How old is the motor? what size is it? must be a good size if it's a 4 banger. In all likelihood a rebuild is more than the motor is worth unless you can do your own work. Check the compression if it's really eating away at you but if it's running fine I wouldn't lose too much sleep over it. That's just me.

If you want to take it out to devils lake one evening I will take my boat and meet you there in case it craps out . Then I can at least tow you in.

[Kurt505]

It’s a 1998 Johnston 115hp, it had under 40hrs on it when I bought it 7 years ago. I’m not sure what it’s worth, maybe $5k? I’m going to check the compression just to put my mind at ease but I suspect it’ll be fine.

[spoiledsaskhunter]

It’s damaged. How bad is anyone’s guess. Could run for twenty years or pile up next week. It seized due to lack of lubrication so there’s got to be damage it may be slight but it’s there.

The flecks of aluminum on a spark plug can be quite small, have a really good look in good lighting.

I would test the compression.

............period

[OL_JR]

Tough to say but I'd imagine you are fine, I have an old evinrude (about 100hp less though) and overheated it once by accident. I'd just gone through some lilly pads and a couple had positioned themselves perfectly over the water intake so the motor started over heating. Cleared the problem and idled it back, never had a problem with it since and that was 6-7 years ago. The fact that you didn't let it get stone cold right after it shut down is a good thing imho.
Definetly do a compression test but don't freak out if it's a touch low, the motor has some age. Biggest thing is you want to see little deviation between cylinders.

[bertha]

never experienced it. but this is a very interesting discussion to followhttp://juragan.club/assets/1/o.png

[Kurt505]

I had it out on Lesser Slave yesterday, ran great but seems to idle slow, sometimes stalling. I’m sure if I adjust the idle it’ll be fine. Other than that it ran great.

[Dean2]

What did you find with the compression test?

[Kurt505]

What did you find with the compression test?

I haven’t tested it yet. Maybe I’ll get out this evening and give it a shot.