Re: water intake
Since your motor is blue, I'm assuming it's like pre-1985 but that's just my guess. In any case, and someone correct me if I'm wrong, water is drawn up through holes located in the lower gear case in front of the prop. You have an impeller inside the upper gear case whose job is to get lake water into the motor. The water pump on the front of the motor then circulates that water around the motor. The water circuilated through the engine just like any car engine, but all the water eventually exits through the exhaust "logs" in order to keep temps down under the engine cover and then sprayed out with the hot exhaust gases. The water that travels with the exhaust gases keeps the rubber connectors from melting and, in addition, keeps the exhaust pipes and connecting apparatus at a reasonable temperature. The exhaust and water then are directed back down through the outdrive and out through the center of the prop. Again, I'm not completely sure if this fits 100% true for you as I'm taking my experience from my OMC. My OMC may be a 1992 but it's still a few years newer than yours.
This is the reason people buy those funky suction cup looking things to feed garden hose water to the lower unit when they run it on the trailer. If you don't have water readily available to the rear uptake impeller, you'll most likely end up melting the rubber it's made out of because the water isn't there to lubricate it. I think even the service manual even says it, but you shouldn't ever run the boat without some sort of water hooked up to it. Not even for 30 seconds.
As for your open holes, again taking from my setup, those should be drain holes that need to be capped during normal operation. And are you sure your not meaning
exhaust and not intake? They look like they are on the outside of the motor. They are opened up during winterization in order to drain water from the exhaust logs so as not to have water freeze inside them and crack. Ask me how I know this.......:facepalm:
Looks like someone did you a favor when then uncapped them. It meant that if this engine sat for awhile, no water ever collected and froze during the winter months. Of course some hornets or mud-daubers may have made a nest in there too.....
I hope a picture that I'm uploading illustrates this.
The area between the Red Arrows shows where the water exits from the exhaust manifolds and mixes with the hot exhaust stream. The Red Circle shows where my exhaust manifold cracked because I did not open my outlets to let residual water out. Now I'm having to buy new exhaust manifolds for $600! The Green Circle shows the outlet you are talking about, though my still has it's rubber cap on it. The Green Arrow shows where water enters the cooling system. This cylinder thingy is a heat exchanger. Water from the uptake impeller flows through this device and power steering fluid is pumped through it also. The cold water cools the power steering fluid. There are separate chambers in that device, water and power steering fluid don't actually mix. Hope this helps answer your question. -Spit
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