[mclamown]

I have the starbord head off of my engine because it was running hot. The thermostate checked ok, so I started checking the fow path so i could fush it. there is only one hole at the bottom that drains out. i can not see where the water comes in. help would shure be appreciate. mike

[rodbolt]

without looking at the block and all my marine tech guides are packed away I can say other than the water come up from the bottom. flows around the cylinders, then out through the T-stat and back down the water jacket then it exits the block via the powerhead adapter.
maybe Ray can describe it from memory. but I still think your dealing with a scale build up in the water jackets.

[mclamown]

Originally Posted by rodbolt

without looking at the block and all my marine tech guides are packed away I can say other than the water come up from the bottom. flows around the cylinders, then out through the T-stat and back down the water jacket then it exits the block via the powerhead adapter.
maybe Ray can describe it from memory. but I still think your dealing with a scale build up in the water jackets.

Thanks for reply . The scale is not the problem it is fairly clean. The power head adapter is not on this one or ijust don,t see it. The Johnsons used a rubber hose to bring water in then it drained out the bottom. Think will pull the other head a have a look it was not getting hot. Thanks.

[rodbolt]

you wont find it

[Ray Neudecker]

The power head adaptor is the plate the powerhead bolts to. The water path is through the port side first and then the starboard. Low water pressure will normally cause the starboard head to always run slightly hotter than the port and overheat first.
Basic trouble shooting for this would be to start at the water pump, then the poppit valve and on to the thermostat.
There have been a number of posts on this subject prevoiusly that you might want to review. The system is basically the same for all V-6 Yamahas.

[rodbolt]

all 2.6L V6. the 3.1 and 3.3 L v6's are vastly different.