I/O fresh water pickup locations.

[Tazmo65]

I have a ford 302 and volvo aq200 that will draw water up through the leg when at idle but not while the boat is up on plane. I know this because at idle i can see water coming out of the thru hull exhaust, but on plane the water flow stops and the engine gets hot. I would like to set the boat up to draw cooling water from under the hull instead of up the leg. Can this be done on an I/O boat or are there other options? If so, what would i need to do it?

 

[blouderback]

Re: I/O fresh water pickup locations.

Could be that your impeller needs to be replaced. While at idle speed, it has enough "oomph" to pump enough water for the engine, but at higher rpms, the old impeller can't keep up. Impellers should be replaced every few years.

 

[Chris1956]

Re: I/O fresh water pickup locations.

Taz, There are plenty of I/O boats with thru-hull water pickups. These are normally used on V-8 fresh-water cooled I/O motors where the LU inpeller simply cannot supply enough raw water to keep the heat exchanger happy and the motor cool. These boats have an optional belt driven, engine mounted raw wate pump.

I think you should test your current setup, and figure out what is wrong with it. You can start with a raw water pump test, and see if the raw water flow diminshes as speed increases. Pull off the raw water hose, stick it into a bucket and measure the flow ad idle and at high speed for a given amount of time.

 

[Don S]

Re: I/O fresh water pickup locations.

You probably have a bad hose connector on the drive where the water goes into the drive. The end corrodes off the fitting. As long as you are going slow, that part is under water and the pump sucks water from the hose. As soon as you get on plane, the connection is above the water and your pump is sucking air.

 

[Tazmo65]

Re: I/O fresh water pickup locations.

Thanks for the responses. This drive does not have an impeller in the drive. Instead it has a raw water pump mounted on the engine in addition to the circulation pump. I do think it is in fact sucking air on plane. I did do a test on it. I filled a barrel with water and lowered the drive in it up above the water inlet on the leg and could not get it to suck water at all. So i took the hose off the fitting on the drive and put it in the same tub, bypassing the drive and it picks up water quick and flows a steady amount of water at all rpm's. I will check the fitting on the drive but the drive is old and the pin that the drive swings on is getting a little loose also and it could be sucking some air around it. What kind of through hull fitting would i need and where would I mount it, in the bildge? This boat rides on a bunk trailer and I wouldn't want it to get tangled up in the bunks.