1978 85hp Evinrude cooling question

[MadtownChris]

Hey guys,

I live on a river and watch the frequent boat traffic go by. When I see 1970s era Johnsons or Evinrudes go by, I compare them to mine and have a basic question.

On many of the running motors I see, the high ports on the back are not producing water/exhaust. By high ports, I mean the twin holes pictured in the image attached.

On my motor (a 1978 85hp Evinrude), I've already replaced the thermostats since I had an overheat. Now, a minute or so after I start my engine, the ports start producing warm water. I've felt the heads and it seems like they come up to temp and then the therms open and that's what makes the water come out of those ports.

So my question for you is why some motors I see passing by seem to produce nothing from those ports yet mine consistently spits warm water. Is there something wrong with mine or theirs? Or are there other designs where those ports work differently?

Thanks, Chris

 

[emdsapmgr]

From 1968 through 1977, the V4 crossflows all had a single vernatherm (thermostat). The characteristic of these engines was to put out only water droplets along with the exhaust from these exhaust relief ports when idling. My 72 100 hp and 76 135 were like this. Water droplets only once the thermostat opened up. From 78 and up, the V4 crossflow engines had dual thermostats and a changed exhaust adapter. These engines typically do put out much more water from these exhaust relief ports when idling and the thermostats open. In addition, once the boat is on plane, you should get two steady streams of water from these two ports. That's normal. Let a buddy drive your boat and go back to check the water flow of your engine when on plane...