Plugged in the block heater for a couple of hours for the first time ever and went to start and noticed a small puddle under the front of the truck. Crawled under and there was a small leak from the big hose between the rad and water pump. Wiped it off, unplugged the heater, drove the truck for several errands checking at each stop. No more leaks. Have driven it several more times since and not a drop, but I have not used the block heater since.
Could this be caused by the block heater causing the hose to expand faster than the pump?