TOPIC: Help ID this 50hp Johnson, plus cooling question

I jsut bought a 1958 Mohawk 14 runabout. It came with a Johnson 50, but certainly newer than 1958 (guessing 80s?) Can anyone help ID it? Should they pump water out the exhaust ports that are right below the power-head all the time? Or is there a thermostat that needs to open? Or should it even have water coming our o there (is it just exhaust)? Reason I'm asking is that we ran her with earmuffs on the trailer and it wasn't pumping water out the dual exhaust ports. The broker wasn't sure if it just needed to warm up, if there was a problem with the muffs, or whether it might need an impeller or water pump. Also, any idea how hard it is to replace the impeller or pump and reseal the lower unit?

That motor is 1971 or newer, as that was the first year of the 2-cylinder 50. A model number will narrow it down. Number is located either on a tag on the clamp bracket or on a welch plug located on the cylinder block. I am going to guess it is later 1970s as the earlier models had a heftier lower gear housing and yours appears to be the later small profile version.

Water will come out those holes only when the motor is in the water as that is an exhaust relief. It needs the backpressure of the prop outlet being under water to force water out of the upper holes.