Say you just picked up that project from out of Farmer Ben's back 40 or the barn, after he told you, " It ran when I parked it here" So you got it home, put a battery in, a little gas down the carb, hit the key and....... Nothin. Stone dead, locked up tight from sitting. Well, here's an old school way to get the old girl runnin on the cheap, and diagnose any issues.
Step 1. Remove all the spark plugs
Step 2. Fill all the cylinders with Diesel fuel, replace spark plugs
Step 3. Let it sit for a week. Go ahead, do your day job, drink some beer, whatever.
Step 4. Remove plugs, get a big ratchet with the proper socket and extension if needed to fit the crank pulley nut, attempt to manually turn over. Won't move? Put plugs back in, let it sit for another week.
Step 5. Try step 4 again. If it works this time, proceed to step 6
Step 6. Got it moving pretty freely? Turn it over by hand until you have most of the diesel out of the cylinders.
Step 7. put in some new spark plugs, change all the fluids and put in a strong battery. Dump a little fuel in the carb and hit the key. Did it start?
Didn't start or even turn over? You got bigger problems to address here bub. Now that it's running, you probably noticed that it's not running real smooth, and its blowing a little blue smoke. This is normal, unless it keeps smoking after all the diesel is burned out of the engine. I also hope you put fresh gas in the tank or even rebuilt the carb while the engine was soaking. Now that it's able to run without help from you, you can either plan the rebuild if it's truly hurt, or run it as is if it's all ok. I've used this method many times and the only time it hasn't worked was when the engine turned out to be blown up.