About a year ago I got this junkyard LM7 5.3 motor swapped into my truck. I did maintenance work on just about every component, but the bottom end is untouched. It has been running great for a year now and I've not had any problems with it. Then, yesterday I was underneath the truck doing some suspension work and noticed this strange wet spot on the side of the block. It was coolant but it had no source, as if it emanated from the side of the block! After cleaning it up, the spot remained dry. It wasn't until running the engine up to operating temp that I discovered there was indeed a hairline crack in the side of the block and coolant was slowly seeping out. So little that it would evaporate and dry before ever dripping on the floor. The crack is about 1" long and wraps around the vertical ridge on the block. I've drained the oil and there is no coolant in the oil, so I'm not too worried that this crack has propagated internally.
After reviewing photos from when I bought the engine, I realized that this has been leaking since before I acquired the motor as you can see a stain on the block from the leaking coolant.
At this point, I'm trying to decide what to do. I know the correct solution would be to start looking for a new block, but I'm wondering if there's anything I can do to try and stop this leak for now. I'm already in this far with this motor so what would it hurt to at least try something? Any recommendations or suggestions from the collective wisdom of this forum would be greatly appreciated!
