What to do, ran 2 stroke without oil for an hour or so.

[rdetzel]

Long story short - I drove the boat for about an hour without any oil* before the engine stalled upon deceleration and wouldn't start back up. Once back (towed) I realized my mistake and switched it over to the correct fuel and was able to start it but only with the fast idle up..if I lower the fast idle it stalls out. How much damage did I do...should I just run it with the correct fuel for a while on fast idle to see if I can fix things? It's running, but I don't know much about engines so I'm not sure that means much. It's a Mercury 25hp (25EL 2002)

* The thank wasn't empty when I added fresh gas so there was some oil but the ratio would have been super low.

 

[Rick Stephens]

I would suspect both cylinder scoring and bearings overheated. Twas me, I'd disassemble and go through the motor. I'd bet the least is bore job with new piston n rings, but wouldn't be surprised needed attention in the bottom end.

 

[rdetzel]

Will running it (with the properly mix) hurt anything? Basically, if I can get it back to idle for the season I would be happy so I can use it.

 

[Rick Stephens]

Will running it (with the properly mix) hurt anything? Basically, if I can get it back to idle for the season I would be happy so I can use it.

No idea. Depends on if any of the bearings are shot. If it starts knocking, the answer then becomes, yes, it will hurt.

 

[roscoe]

Chances are that running it will do more damage.

 

[fhhuber]

Probably serious to severe damage from running that long without oil and running it more before repair will likely trash the engine.

Slim (very slim) chance you got away with mostly just premature wear, but inadequate oil gets the engine VERY hot. I don't know if that engine has a safety thermostat to kill it when it gets that hot, if so that might have saved it. It still needs to be inspected for what the effects are, even if it has the overtemp safety...

 

[gm280]

The fact the pure gas will actually wash oils out of every part internally, isn't good news at all. I would be extremely surprised if it ever runs properly again until it gets serviced now. JMHO

 

[ondarvr]

After running that long without oil, and the fact that it stopped running, means there's damage, it won't fix itself, and most of the time while it may still run for now, the amount of damage done already means it will fail in the near future.

​The question is will the there be more damage done when you run it until it completely dies, or if you rebuild it now will it cost less and be easier, well, there's no way to know. There may already be damage done to the crank, and if so it means a total rebuild from the bottom up, if there's no damage to the crank now, and the entire motor lets go, you may damage everything beyond repair, even the block it's self.

​Whether rebuilding it is worth it is up to you.

 

[oldboat1]

Dunno. Doesn't sound good, but how hot was the engine?

Check compression. It would be useful if you have a prior baseline reading, but if compression readings are on the low side, you might pull off the head and exhaust covers. Check for scoring, but at a minimum assume warping, and reassemble covers after resurfacing, using new gaskets. Torque to specs, and run the engine a bit, then retorque and take another compression check. After reassembly, it may run pretty normal for the rest of the summer -- sounds like you are not interested in running the bejeebers out of it.

Stuff happens.... Don't know if you would take on a rebuild yourself, if it comes to that, or pay for one -- or might find a replacement powerhead from a donor motor. Always options.

 

[rdetzel]

I probably cooked it...expensive lesson I guess. A friend suggested I just scrap it and get a new engine, maybe 4 stroke since I'm upgrading. I no next to nothing about engines so repair is out of the question and not sure it's worth fixing anyway since it's loud and smelly. I also don't like that it doesn't have power trim, our slip has big rocks so this engine and really far up to avoid them but it makes for a crappy ride (over rev too if we hit a big wake because it comes out of the water). if I upgrade to a 4 stroke I'd probably get power trim too.