When should water be pumping out the back of the engine?

[twr7cx]

I'm not sure on the proper name for that rubber thing that the water squirts out of the back of the engine. We also just call it the **** tube.

Picture of what I'm refering to:




Just wondering on a 1993 Mercury 60HP 2-Stroke 3-Cylinder 0C16180, when should water start flowing out of this?

Basically, I didn't realise that you shouldn't run an outboard without water flowing through (I've never had an issue moving cars that I was playing with short distances with no water if they're cold, and assumed boat engine would be fine to) - I just assumed that if it was only for a short period and the engine was cold it would be fine. But according to the Seloc manual which I just go, it destroys the water pump impellor.
So I connected water up and ran the engine, and no water came out of the squirter. I disconnected the hose to the squirter, checked for blockages, and tried again, same deal.

The black hose running left to right I checked for blockage, as well as the squirter (they were clear):




So I shut the engine down, with the assumtion that I had wrecked the water pump.

 

[twr7cx]

Re: When should water be pumping out the back of the engine?

This afternoon I removed the lower gear housing, and checked the water pump. Looks fine to me:






So I did some more reading, and it seems the motor has a thermostat, do these thermostats mean that absolutely no water flows all the way out until the engine is warm, or just that it limits the amount of water?

 

[jarand82]

Re: When should water be pumping out the back of the engine?

water wont flow out of the engine untill the thermostat opens.

 

[j_martin]

Re: When should water be pumping out the back of the engine?

The tell-tale won't squirt till the engine is warm, usually 30 seconds to a minute.

While you're there, replace that impeller. You got most of the goodie out of it. They will overheat enough to lose their tension in about 10 seconds without water. The water pump in a car is a centrifugal pump, and there is no contact between the impeller and anything else. It doesn't hurt them to run dry.

A rubber impeller pump relies on the tension of the rubber to develop pressure. If the rubber is soft, the blade edges fall away from the chamber and let the water slip past them. Even if it looks good and follows the chamber surface, it could be weak and not pump well.

hope it helps
John