Seized Vanguard 16HP Now Spins Free?
 

Long story so please bare with me.

My father gave me his Cub 1641 with a "seized" 16HP Vanguard.

He got it stuck in the mud and apparently it seized hard.

He mows a big hill so I'm a little worried the engine was starved of oil.

After I got it home I tried to turn the engine over with a socket wrench and it turns fine. I can see both pistons move up and down too.

I stuck a borescope in both sparkplug holes and the pistons looked intact. The cylinder walls didn't look scored either.

Stuck the borescope down in the dipstick tube to see the crank and I don't see anything obviously wrong.

My thoughts are cottonwood clogged the mesh intake on the side panels causing the aluminum pistons to get hot enough to seize in the iron bore sleeve. When the engine cooled off it "un-seized."

The 1641 has 576 hours on it and he's taken pretty good care of it as far as I know.

I plan on dumping out the oil to see how shiny it is.

No compression test yet as I'm scared to turn it over real fast if a rod/crank is bent.

What's everyone think?

Am I looking a new engine, teardown, or make sure everythings ok and run it?

Also, I can redo the borescope colonoscopy if you guys would like to see..

Any help would be much appreciated,
Steve

First, welcome to OCC.
If it had adequate oil in it, prolly the rotating bottom end is ok,
but your suspicion of the cylinders siezed due to overheating is a good a guess.
@ this point you have nothing to loose to give it a try running.
Obviously it has ring damage and possibly cylinder and piston scoring, but it is a crap shoot.
One might get real lucky on the scoring issue.
So you have some choices:
shoot some oil in both cylinders and crank it over a few times.
(a couple of pumps with a squirt oil can)
Then try to run it keeping the rpm's low till you see if there are any obvious strange noises, if not, run it a while.
Then change oil while hot, letting it drain well.
If all seems good then put it to work watching the oil consumption and smoking on starting.
It got hurt seizing, no doubt,
and the proper thing to do is rebuild the cyl assy's minimum.
That said it might run a long time as it is, or it may turn out to be hurt enough it needs attention now before using.
You make no mention what your long term goals are, so your call.
Luck!

Thanks for the reply George.

I think I'll do just that. If I can get the garage warm enough I'll do it tomorrow.

As far as long term goals go. I like how the 1641 mows so I'd like to keep it even if it means rebuild/replace the engine.

Be aware it is gonna smoke a bit because of the oil you squirted in the cyl's.
It is gonna be cold Sun/Monday nights, burrrr:bash2:

Not familiar with that engine. Could it be a magnet came loose?

31 degrees here currently. It could definitely be worse I guess.

I'm not familiar with this engine either so I don't know if a magnet in the flywheel could have come loose or if it's common. I'll check for spark.

I think he is referring to the charging magnets on the inside of the flywheel.
The KT & Magnum kohlers are known for the magnets coming unglued after 35 some years of service.
I don't know what your engine set up is.

PTO bearings could have seized as well and then let loose.

What he said. I bought this one for $280 seized, turned out to be a bad PTO.

Hmm how would I go about diagnosing bad PTO bearings?

The ground was disconnected from the tractor. When hooked up to the battery the ground wire is only long enough to bolt to one of the sheet metal guards. Anyone know if this is correct?