1991 225hp No cooling water over 3000 rpm

[v12mac]

I have a 1991 225hp that is over heating.<br /><br />Question If I have cooling water at the exhaust relief ports but not at the tell-tail (tell-tail not pulgged up), where should I start looking for the problem? My gut says thermostats, any ideas?<br /><br /><br />History: Gear case tore up due to water intrusion, while limping back to the dock flow from tell tail stopped. It never was srong since I owned the boat. I installed a junk yard case and a new complete pump kit it seemed to have a lot more parts and o-rings than the existing one. I put the case back on and no water at the tell tale but good water flow in the exhaust relief. I figured I had a clog in the tell tail lines so I didn’t give it too much thought. I ran the boat idle speed last night 40 min or so and got an over heat alarm.<br /><br /><br />Mac

 

[ob]

Re: 1991 225hp No cooling water over 3000 rpm

Could be one or more of several things.T/stats not operating freely,waterpump discharge tube not seated properly,worn out waterpump or combination of all.I'd replace the waterpump and T stat assys. if its been a while they were changed.

 

[v12mac]

Re: 1991 225hp No cooling water over 3000 rpm

I replaced the complete pump with the case swap.<br /><br />So I fired it up, and plenty of water from the exhaust ports. Pulled the stats and they looked old possibly stuck. I unscrewed them from their rubber gaskets and put the covers back on. Fired up and no water at the tell tale but the engine was running at the right temp (hand on cyl head 5 sec.) So I pulled the hose that runs between the t-stat housings and noticed that there was hardly any water flowing between them even wierder there was some exaust smoke in the hose????. Then I pulled the littel hose that connects to the small nippel at the back of the motor and it was just dribbling. So I blew some air in and whola! good flow of water. Re connected to the y connector just before the tell tale and I have a good steady streem of water at the tell tale. <br /><br />Question: How much water should be flowing thrugh the hose connecting the t-stats? Could the stats not oppened due to no water in this part of the system?<br /><br />Mac

 

[v12mac]

Re: 1991 225hp No cooling water over 3000 rpm

I am loosing cooling when on plane for about 30 seconds. I have good flow idle to aprox 3000 rpm then I loose all cooling water to the motor and I get steam or exhaust out of the tell tail???? <br /><br />Also when I start the motor it seems like it takes a min or so for the pump to prime.<br /><br /><br />Ideas??<br /><br /><br />Mac