Is my water pump bad???

[mbarth]

Splashed my boat at West OC boat ramp on Friday eavening. Half way across the bay the high temp alarm goes off. Son of a bitch!! Anways to make a long story short I just got done installing the new water pump and thermostats. What I don't understand is that there didn't appear to be anything wrong with the old one. It was only in one season. Is it possible that the key way may have slipped out? When I pulled the housing and impeller off the shaft the key way fell on to the ground so I really had no way of knowing whether it was in the impeller before I pulled it off. I do not think there was anything wrong with the thermostats, I just replaced them as a precaution. My engine is a 150 HP Mercury year 2000 model. I'll be putting the boat back in the water tomorrow so I guess I'll know soon enough whether my repair will fix the problem. Has anyone had the same problem? Any help would be appreciated. Thank you, Mike

[ericjp]

If the key wasn't in the pump it wouldn't be working at all and it would of over heated quickly. Also if the key wasn't in the slot it would have most likely gouged up the inside of the pump or been pumped out somewhere else. Did the thermostats look ok. Did you test to make sure they opened? You can put them in a pan on the stove to check to see if they are opening.

[Bob H.]

The key can't come out. Assuming everything was properly installed, recheck the pump output tube connection. Sometimes the bushing on the line to the powerhead plays games. I'm not familiar with the 2000 but does it have a poppit valve to relieve excess water pressure? Do you have a water pressure gage? Poppits either stick or the spring breaks. If the poppit sticks the thermostat can't handle enough water flow at high rpm's.

[C-Hawk18]

That motor should have the poppit valve and that will probably be your problem.

[mbarth]

I ran the boat this morning and all seems OK. It still seems a little odd though that it overheated. I checked the old thermostats in a pan of hot water and they opened immediately. I think I will replace the poppet valve but I can't seem to locate it. The guy at Shorts Marina was very helpful and that was also his recommendation. My Mercury repair manuel is at home so I'll have to replace it next time we come down to OC. Thanks for the help, Mike