Re: recirculation check valve E200 Evinrude 1997
Well....they are not located on the heads.....
There are actually twelve recirc valves, six that are visible and six that are covered up by the reed blocks.
The visible ones are installed into the sides of the front crankcase half, and have recirc hoses running to the opposite cylinder nipple that is installed in the sides of the block. What I mean by that is that the hose for #1 recirc valve goes over to the nipple for #2 cylinder. Likewise, the hose for #2 recirc valve goes over to the nipple for #1 cylinder. And so on down the block.
You have to remember that the intake on these loopers crosses over in that the intake plenums for #1,3, and 5 is actually on the OPPOSITE side of the engine from the actual cylinders. Obviously the same is true for #2,4 and 6.
The six that are hidden are pressed into the front crankcase half, about the size of a dime, with a screen over the visible face.
They have an o-ring on them, and are a complex little device with front and back openings, as well as side openings. They are hard to test, and are hard to get out of the crankcase half without destroying them.
Go to shop.evinrude.com, drill into your motor parts pages, go to the cylinder and crankcase page, and they are item reference numbers 11 and 12. Eleven is the visible one with attached hoses, and twelve is the hidden one.
They are expensive little boogers.