Dingy outboard heating up

[Westside]

I have a 3 year old Nissan 25 HP outboard on 11 foot AB Rib, hangs off my 4388 nicely. Recently the light sensor went on and I noticed engine getting hot. Pee tube was only spitting water at half the normal discharge rate. Pulled lower unit expecting to find impeller problems, all intact. All tubes were clear no obstructions, everything looked brand new, engine has maybe 30-40 hours. Ideas on what to check next?

[Norton_Rider]

It may have a bad thermostat or too much scale buildup in the cooling passages. Use Salt Away in a dispenser and run the motor on the hose. Do it twice. This may dissolve salt deposits from the cooling passages.

[brad4550]

What Norton Rider said and Might also try using heavy fishing line to clean out pee tube.if its still not right I would replace impeller and housing
Good luck Brad

[Westside]

For sure will do all the above, so far have not found a skmatic of the cooling system up in the motor. Good manual on line but may need to get into the cooing jackets around motor. Never have taken apart an aoutboard, lots of experience on disels. Tubes, impeller were like brand new so makes me wonder what else could be.

[Machog]

My cooling water stopped running, salt build up, despite flushing extensively with fresh. There a smaller rubber tube under the engine cover on the port side roughly in the middle that goes vertically down. Pull off the rubber, poke a thin piece of wire gentle down and that cleared mine. Other issue I had was a frozen steering arm, so now I really lube and clean that before I put dink away for the winter. Machog

[Amx1kjw]

I have a 99 Nissan and had the same issue with water flow. Noticed very weak stream of water coming from discharge. Checked water pump in lower unit which was ok but replaced anyway. Found rubber tube from water exit in block to the outlet in the cowl with obstruction. Cleaned out and all is back to normal water flow. This is the second time I have had a problem with obstruction on this engine the first was a small bug in the carburetor not allowing air to mix with the fuel.

[The_Salty_Kiss]

You can try running the engine in a bucket of Barnical Buster. This stuff works pretty good cleaning out salt build up and growth.

[Steadfast70]

My experience with what appeared to be over heating on my 20 hp Honda turn out not being a plug problem or impeller problem as replacement did not solve over heating alarm and auto shut down.. Did all the usual stuff to fix still having engine going done with over heating. Then used heat gun (should have done this first) and it appeared engine was not over heating. Replace the over heating sensor/sending unit and problem corrected.