Hello All,

I recently purchased a boat with a ~1986 Mercruiser 170 (inline 4). It
ran fine and cool when tested before purchase.

Now that I have it home, I fired it up for the first time in the yard.
It fired fine and ran smooth, but started to overheat within about a
minute or so. I turned it off before it reached 200. I noticed that it
was not outputting any water out from the gimble area of the outdrive.
When tested before purchase, there was significant water coming from
that area.

This leads me to belive that the raw water pump in the outdrive is not
functioning properly. To test this theory I disconnected the hose
leading from the outdrive from the heat exchanger. I then restarted
the engine and let it run for about 30 seconds. No water came fom the
hose.

This still leads me to believe that it is the outdrive water pump. Odd
thing is, the seller told me that the water pump had recently been
rebuilt. He even commented during the pre-purchase how good the outlet
flow was, and I agreed.

So I guess my question is... if I am not getting water from the hose
into the heat exchanger, is it definitely the water pump? Can the
voltage regulator interfere with the flow? (it is between the outdrive
and the exchanger). Is there any other way to test the raw water
pump?

BTW, I did check the water inlet area of the outdrive and it looks
clean. The earmuffs are making good contact and there is good water
pressure from the hose.

Thank you for your assisatnce!

John