Raw Water Outlet

[gilbugs]

I have finally got to the point that I have started the motor on my 87 Sea Ray Seville Mid Cabin. I hooked up the flush muffs and turned on the water and started the motor. I let it run for about 5 minutes at idle and the temperature never exceeded 175 degrees, however I did not see any water flowing out of the outdrive or hull so I got concerned and checked the engine bay. There was water spraying out of the end of the heat exchanger so i shut the motor down. I have a closed system so my guess is the antifreeze kept the motor from over heating at idle.

What is my issue here? Is the raw water pump bad? Even if the pump was bad shouldnt the water have flowed through the system and exited some where? Where does the raw water exit on this boat?

It is a Mecruiser 170 hp with an Alpha One Out drive.

 

[dubs283]

Re: Raw Water Outlet

Even if the pump was bad shouldnt the water have flowed through the system and exited some where?

no, if the pump were bad you wouldn't be getting raw water to the heat exchanger

Where does the raw water exit on this boat?

it exits though the transom relief hole(s) and the exhaust passage on the drive

the problem is with the heat exchanger - its leaking raw water, very badly according to your symptoms

might be time for a new heat exchanger, or you may be able to get away with replacing the end cap or even just a gasket

its possible, that running for five minutes with no water cooling the exhaust system, you cooked some stuff in the manifold/riser assy, exhaust flappers, and the drive - especially the plastic water pump parts

 

[gilbugs]

Re: Raw Water Outlet

Thanks for the info Dubs283.

I guess I dont understand that if the raw water pump is working to get water to the heat exchanger, how I could ove heat the water pump in the drive? Does the water also return through the water pump, or are you saying that the heat from the uncooled exhaust would be enough to cook the water pump even if it is pumping water?

It looked to me as though the heat exchanger was over pressured and the water was blowing by the gasket on the end of the heat exchanger. So I must have a clogged retrun on the heat exchanger that is preventing water from passing back into the drive and the outlet on the hull.

I ordered a service manual for the drive, but I am not sure if it will cover the cooling ssytem for the engine. I do not see where the water retrun in plumbed to hull anywhere????

 

[stonyloam]

Re: Raw Water Outlet

I suspect that you are correct and the raw water passages in your riser may be plugged, or the exchanger is leaking so mugh that the water is not getting up there. If the water is not entering the exhaust riser, there is nothing to cool the exhaust and you can overheat your exhaust shutter, and you can overheat the outside of the raw water pump, and in an extreme case melt some of the plastic. On your engine the raw water from the pump enters through the transom, goes through the water cooled regulator, into the front of the exchanger, out the aft hose, into the p/s cooler (if there) and out through the exhaust riser. the water circulating through the exchanger (and out the end) kept your engine cool. You could try pulling the hose off of the aft of the riser (the one from the exchanger) and try blowing through it. Good luck.

 

[stonyloam]

Re: Raw Water Outlet

shouldnt the water have flowed through the system and exited some where?

It did, out the back of the heat exchanger.

 

[stonyloam]

Re: Raw Water Outlet

I ordered a service manual for the drive, but I am not sure if it will cover the cooling ssytem for the engine. I do not see where the water retrun in plumbed to hull anywhere????

You need Service Manual #8, Mercruiser Marine 4 cylinder engines (not GM).