Mercury 25 two stroke no cooling

[LEOKAT001]

Help i just bought a mid 80s early 90s mercury 25hp and it runs awesome only issue is im not seeing any cooling water being discharged... Iv'e taken the lowerunit off and it all looked good the inpeller was ok as far as i could tell... Anyone have any ideas?

 

[Mi duckdown]

Re: Mercury 25 two stroke no cooling

If you removed the lower unit you should have changed the impellar. 25 bucks.
that said, there may be an obstruction in the tale tell (pee hole). run a piece of weed wipper string up the pee hole.
that year may or may not have thermo stat. Got serial number?

 

[RadarRick]

Re: Mercury 25 two stroke no cooling

Might as well change the whole pump - not much more $$ and, even though everything might look ok, it could be inefficient - especially if you don't know the history. You can also run water or air up the water uptake tube to see if it flows through ok.

 

[rg2]

Re: Mercury 25 two stroke no cooling

I agree with replacing the impellar while you had the LU off but assuming it's back on now I would check the thermostat, if so equipped, located where the tell-tale line mounts onto the motor block. Remove the thermostat and test it in a pot of water as described in the manual to make sure it is functioning properly (i.e. opening at the correct water temperature).