I put oversized o-rings in my water pipe, less than $5.00 instead of a six hour round trip to the dealer. Problem solved.

 

It’s been two weeks since I picked up my 2019 Rebel 300 from the dealership.
The service manager agreed that the water pipe and the upper and lower O-rings needed replacement which was done under warranty. The problem is now solved and I’m confident that it will not happen again as it’s been two weeks and a lot of miles with no more issues!
my recommendation for those of you who have experienced the rebel coolant leak is to insist that it’s fixed under warranty and that the water pump is replaced as well as the upper and lower O-rings. The water pipe was defective as well.......it wasn’t milled to meet flush, which was a manufacturer defect. The new water pipes are correctly milled.
This is the bike from today’s ride:

awesome to hear. glad they fixed it for you, and there are no more (as of now) issues!