Strange exhaust behavior during winterizing

[Pmt133]

Both. When the thermostat opens that feeds the manifolds. The check ball T on the housing otherwise feeds the elbows with bypass water until it opens.

 

[Bondo]

Ok, I'll make sure I drain the liquid from the bottom of the manifolds to make sure. But I have a more basic (maybe stupid) question: Does the coolant come into the manifolds from bottom and goes up to the risers? Or does it come into the riser hoses (that I provided the picture above) and go down the manifolds?

Ayuh,..... Correct,.....

 

[Scott06]

Ok, I'll make sure I drain the liquid from the bottom of the manifolds to make sure. But I have a more basic (maybe stupid) question: Does the coolant come into the manifolds from bottom and goes up to the risers? Or does it come into the riser hoses (that I provided the picture above) and go down the manifolds?

as bondo mentioned it come up through the manifold bottoms and out the risers.

The separate hoses feeding the elbows supply cooling water to the exhaust when the thermostat is not open. This is a warm manifold system vs the cold manifolds with only the supply to the manifolds that is supplied cold water all the time. The idea was to cut down on condensation in the manifolds, not sure it makes much difference in the real world. Have had boats with both designs and they both work fine

 

[Lou C]

I have the OMC/Volvo style on my 4.3 Cobra (Volvo style manifolds, which is a cold manifold design) and these run at only 145* when on plane and at idle, usually at about 100. I ran the engine at idle for a while and then took the manifolds off to do other maintenance work and did find some condensed moisture inside, so maybe Merc's system does really work to eliminate that. I recall reading that they would have to stay above 120* to burn off the condensation.