Any tips to try and unseize an old international tractor? It was running two years ago.

Hi,
Do you mean that it ran before it sat for two years? Why did it sit? Make sure it is full of oil, remove plug and pour a mixture of oil and kerosene.in the plug hole and attempt to turn it at the front end of the crank( if it is a horizontal, or the top end on a vertical.
Peace,
Clarke

Thanks for the reply.
The previous owner wired the starter with what I'd guess was undersized wire, one day when starting the tractor the wire burst into flames. Myself and an electrician buddy re-wired the starter ( after two years of sitting)
I dropped the old oil, had some water in there too. Ran kerosene through the pan and the plugs, then oil, then more oil, finished with a fresh oil change. Recently my farmer buddy hooked on with a larger tractor and we tried pull starting the tractor, got nothing, not even a puff of smoke. I've heard to dump diesel into the plug holes and let it sit ( this is a 50's gas international tractor) might try manually cranking after your advice. Any other tricks or tips ? Thanks

Hi,
Diesel has some lubrication properties, but not that many. Often the older gas tractors were shut down after closing off the fuel supply to prevent gas from drooling into the engine. Once the cylinders are lubricated, manually turning the engine was generally the best.
You may want to check out this link:
TractorData.com - International Harvester tractors sorted by year (http://www.tractordata.com/farm-tractors/tractor-brands/ih/ih-tractors-year-sorted.html)
Peace,
Clarke