I concur with that. My 5411 also sends steam out the stern exhaust. When I first tested her, I thought it was white smoke from a blown head gasket. But that's just how she rolls. The 5411 runs cool as a cumumber at 135-140 degrees max. You can rest your hand on the top of the block while running & it won't burn. Not that I advocate this!
She takes a while to spit out water past the water muffler, and she will take even longer if you have the termostat enclosed cooling loop open. Unless it is freezing cold outside I close the loop on the cooling plumbing circuit to the thermostat, & let the straight raw water pump continuously. It did, & does make me nervous to wait until the thermostat opens up after several minutes of running to where it allows cooling water out the exhaust, rather then recirculating it back into the engine block. The only advantage of the thermostat loop is to allow the engine to reach operating temp. sooner, making it slightly more efficient. Being that the engine runs so cool anyway, i don't think this makes much difference in performance. One more tip, run your glow plugs for at least 30 full seconds before start up. Universals have lower compression then Yanmars, etc. do, so they depend on glow plugs to warm the cylinders & aid in start up. Mine starts immeditely with glow plugs, but not at all when cold without them. ps. What we lack in oomph in H. P. we make up for in awesome fuel economy & reliability! Cheers.