587 Engine Got Stuck

[rustytraktor]

New here, hey everyone.

I have a 91 XP with the 587 twin carb. The other day out on the lake it was running fine and then I was twisting around and bucked myself off. When I got back on, the engine would not start. Just the solenoid would click.

Thought maybe it was electrical, and ended up changing the starter but I was wrong. The engine was seized/ stuck. So I pulled the plugs and cranked the pto with a pipe wrench and it freed. Then it turned over freely and I made sure there was no water in anything including the crankcase drain plug.

Tested engine compression, it is 110 psi in both cylinders.

Is there something I should check? I'd like to get it back out there for the summer, major repairs would be preferable during the winter. I did have a bit of an injection oil leak; the filter rubbed a hole through itself on the hull. I ran it for a bit leaking into a rag until a new filter came in, I just installed it.

What are your thoughts to get this thing back out there?

Thanks!

 

[burtshaver2021]

Wow, your injection oil was leaking and you put a rag under it to catch the injection oil and kept riding. That’s a serious need to ride. At this point it sounds like it doesn’t really matter if you damage the machine so why not just ride it? If it will start with a 110 pounds is questionable but give it a try

 

[rustytraktor]

Wow, your injection oil was leaking and you put a rag under it to catch the injection oil and kept riding. That’s a serious need to ride. At this point it sounds like it doesn’t really matter if you damage the machine so why not just ride it? If it will start with a 110 pounds is questionable but give it a try

It was a small leak there was still plenty of oil getting to the pump.

Also going to add that at no point did the temperature indication ring.

 

[mikidymac]

Engines don't just "stick" and keep running. You damaged something and it isn't going to go away. Typically they will not start in the water at 110psi compression.
If you keep running it you might blow the crank out the cases.

 

[tomski]

I have the '91 XP...depending on where you had the rag catching your oil, your pump might not have been pumping sufficient oil. If you had to break the crank loose with a pipe wrench to get it freed up, I'm afraid that yes, the damage is done and she may be fried.

So with that being said, might I suggest blocking off the oil injection,(or not) dump some oil down the cylinders, crank over the motor for a bit. Get new plugs,
Mix your gas, and a little heavy on the oil , and runn'er till the skis fall off !!! Just make sure you have contact with the mainland.

 

[rustytraktor]

Following a lockup like this would a top end be sufficient or necessary to pull and do whole engine at some point?

Also will add previous owner was running blue oil, must have been for years, the tank is permanently blue now. Contributing factor?

 

[rustytraktor]

I have the '91 XP...depending on where you had the rag catching your oil, your pump might not have been pumping sufficient oil. If you had to break the crank loose with a pipe wrench to get it freed up, I'm afraid that yes, the damage is done and she may be fried.

So with that being said, might I suggest blocking off the oil injection,(or not) dump some oil down the cylinders, crank over the motor for a bit. Get new plugs,
Mix your gas, and a little heavy on the oil , and runn'er till the skis fall off !!! Just make sure you have contact with the mainland.

Thank you!

 

[mikidymac]

No, and the oil pump didn't lock up the engine, do not block off the oil injection system.

There is a chance the jet pump locked up but worth checking.

Few things can lock up the engine.
1. Rotary gear.
2. Rotary Valave.
3. Crankshaft.
4. Pistons.
5. Jet Pump.

 

[rustytraktor]

No, and the oil pump didn't lock up the engine, do not block off the oil injection system.

There is a chance the jet pump locked up but worth checking.

Few things can lock up the engine.
1. Rotary gear.
2. Rotary Valave.
3. Crankshaft.
4. Pistons.
5. Jet Pump.

Thanks, definitely not the jet pump I checked that first.

 

[tomski]

You can bench test the oil pump and if it's good, don't block it off. I only said that assuming you wanted to ride it no matter what...my bad.

 

[mikidymac]

You can bench test the oil pump and if it's good, don't block it off. I only said that assuming you wanted to ride it no matter what...my bad.

Not a bid idea Tom.

The oil pump drive gears are plastic so even if it stopped it would just strip the plastic gear. The pump wouldn't lock up the engine. Whatever locked up the engine is damaged and isn't going to fix itself with more riding.

 

[rustytraktor]

Not a bid idea Tom.

The oil pump drive gears are plastic so even if it stopped it would just strip the plastic gear. The pump wouldn't lock up the engine. Whatever locked up the engine is damaged and isn't going to fix itself with more riding.

So hear me out; I'm thinking most probable is the pistons? Especially considering the lockup happened after the engine was killed by the tether, maybe it was hot and then cooled enough to lockup? Maybe I can inspect through the exhaust or with a borescope. Can the head be removed for inspection and re-assembled without a gasket kit around?

 

[tomski]

I wish I could be more help. I've only gotten as far as pulling engines out and reinstalling. This is what's under that head plate after removing the 11 bolts holding it on. I believe your '91 has the yellow motor.

 

[mikidymac]

Engine is shot if the 110 psi compression is accurate. Only option now is to start pulling the engine apart.

 

[rustytraktor]

Engine is shot if the 110 psi compression is accurate. Only option now is to start pulling the engine apart.

I tested again after letting the cylinders sit with oil in them for awhile and with them wet I’m testing 150 Mag/ 140 PTO.

What are thoughts? 110 would have been a pretty much completely dry cylinder.

 

[mikidymac]

Testing with oil will give false high readings. Not the correct way to test on 2-strokes.

 

[rustytraktor]

Testing with oil will give false high readings. Not the correct way to test on 2-strokes.

Good to know, I’ll look into the top end.

 

[rustytraktor]

Update;

Removed engine. Found some blow by and some scratching on pistons.

I am bringing in the engine to a local machine shop for a complete rebuild.

In the meantime I am waiting for a Mikuni rebuild kit. Also going to replace fuel selector valve and bench test oil pump.

Is there anything else to check? Does the oil pump require maintenance? I want to know it will be absolutely ready to rock.

Thanks for the tips,