85 Mercruiser 170 (3.7L)- way to test impeller??

[webnetxpress]

my engine that i'm trying to get back in the water this week seemed to overheat a bit this past weekeend in the driveway. Yesterday evening I pulled the thermostat to find that it was stuck open rather than closed, so that can't be the problem (I'm replacing it with a new one today anyways).<br />I just replaced the impeller kit last week - but it was the first one I ever did. <br /><br />So, is there a way for me to test the impeller in the boat? Can I pull a hose from somewhere to see if fresh water (off my garden hose) is coming in?<br /><br />Thanks,<br />David<br /><br />ps- I've narrowed it down to just three possibilities I think: bad water pump on engine, bad impeller, bad cooling transfer tube. Anything else it could be?

 

[Walt T]

Re: 85 Mercruiser 170 (3.7L)- way to test impeller??

Pull the hose from the pump and stick it in a 5 gallon bucket. Start up and it should fill that bucket up rapidly with no air bubbles at idle.

 

[webnetxpress]

Re: 85 Mercruiser 170 (3.7L)- way to test impeller??

hose from which pump? I have the garden hose hooked up to the engine ear muffs (for better term) and that attached to the outdrive. I assume there is a hose on the inside that leads to the heat exchanger somewhere, but is there another pump inside that also draws the sea water in?? I thought it was just the impeller on the outdrive...<br /><br />Sorry, i'm just new to this and a bit confused.

 

[Walt T]

Re: 85 Mercruiser 170 (3.7L)- way to test impeller??

The impeller is in the drive. Look under it and you'll see a hose going from the drive up into the boat. Find that hose in the engine compartment. It most likely goes up to the Tstat housing.