Waterpump: engine vs. outdrive?

[mjrhoads]

I'm wondering if there is an easy way to determine which water pump has gone bad: engine or outdrive (or both)?<br /><br />The engine/outdrive is a GM 153CI/120HP 4-cylinder with Pre-Alpha Mercruiser outdrive.

 

[Ralph 123]

Re: Waterpump: engine vs. outdrive?

In my case, when I reved the engine the temp would drop because the cirulator pump compensated for a bad water pump in the outdrive. If your does the same thing it is likely the outdrive.

 

[Boatist]

Re: Waterpump: engine vs. outdrive?

Buoy-10<br />Is the engine overheating and if so at idle or wot??<br />In the water or a tank but not on muff pull the hose from the outdrive to the engine. Start the engine if get good water flow there then impeller in outdrive ok. If overheating then could be thermostat, water circulation pump, Manifold or riser, head gasket, timing.