I built a engine and did not follow instructions of the Best rear main seal I used. I packed it in just a little, not like the old seals, but more then I should have. The engine ran fine and sounded good, no problem at all ( on the test stand for break-in). After 25 minutes of run time I shut it down to clean up and rest a bit. Went back out after a break and the motor was locked solid, dad and I about flipped the stand over trying to get it to move. I was upset so we shoved it in the garage till the next day. I would turn over and fire right the next day, so we figured no bearing or crank damage. Using a infrared heat gun, we started checking for trouble spots while it was running. It didn't take long to find, the back of the crank was heating up pretty quickly.
I pulled the pan off and rear main cap, the area of the seal was changing colors which indicated heat. I replaced the seal and follow the directions this time with no other troubles.
Guess I am saying, check everything,
Joe
