Model 70 problem - locking up?

[antiwork]

So I have this old Model 70 thats been in the family since I was a kid. For the most part, it's been a great old tractor. Now that said...

The last two times I've run the thing, At some indefinite time after I start running the thing, it will slowly die out, then refuse to start again. The first time was after maybe 45 minutes of run time, this last time, maybe 10 minutes.

Both times that this has happened, I've noticed that it appears that the motor just all but locks up. The starter will try to spin, but just can't crank the motor over. Likewise, I can't seem to spin the motor over by hand using a bar in the front pulley.

It seems like after it cools down some, I can work the bar back and forth a little bit and loosen it up, then it's fine.

What the heck is going on with this thing?

 

[rcbe]

amoung several possibilities, could be trash buildup under engine air cooling shroud sheet metal causing overheating; may be trash in fuel line/filter or fuel tank cap vent stopped up...
No smell of gas in oil from dipstick, I hope.. ?

 

[jet62095]

Have you changed your oil recently?
Is there enough oil in the sump?
This is an odd problem, I've been working on older cubs for about 5 years now and I've never heard of it.