80HP Yamaha 2-Stroke Overheating Issue

[fishfun83]

Today I replaced the thermostat and the PCV valve on the engine. When I crank it up at the dock the cylinder head cover gets pretty hot. Is that normal for idle? The outer exhaust cover was cool to the touch.

[TownsendsFJR1300]

Today I replaced the thermostat and the PCV valve on the engine. When I crank it up at the dock the cylinder head cover gets pretty hot. Is that normal for idle? The outer exhaust cover was cool to the touch.

If water is NOT FLOWING TO that area DUE TO A RESTRICTION it will get hot..

How much salt was found?

[fishfun83]

If water is NOT FLOWING TO that area DUE TO A RESTRICTION it will get hot..

How much salt was found?

I wouldn't say there was too much salt. More like mud than salt deposits.

[zenoahphobic]

I think it appropriate again to point out the pee stream limitation. It just shows your pump working and not that it is circulating through all of the engine.

A strong stream fools the mind to believing this. In fact a strong stream can result from a blockage upstream, and not indicate a weakening pump even. Don't know why not a better design; fools a lot of people.

[99yam40]

looks like that stat was not even closing properly.

without real temp numbers, how is someone suppose to even guess what is going on.

Did you try to flush the system out like I said?
or did you just replace those parts?
You did say it looked like mud, so that should be able to be flushed out with water and compressed air

[TownsendsFJR1300]

looks like that stat was not even closing properly.

without real temp numbers, how is someone suppose to even guess what is going on.

Did you try to flush the system out like I said?
or did you just replace those parts?
You did say it looked like mud, so that should be able to be flushed out with water and compressed air

I bet that stat wasn't even opening as nasty as it is...

Agreed with all that "mud" in there to pull the stat again full with a bunch of water, etc, (WAY BEFORE pulling the head)..

If you can get a pressure washer wand to reach INTO the cylinder area, that might work better (if the muck doesn't flush out easily)


Seems "muck" prevents / hampers salt erosion!!

[holmen78]

I would open up the exhaust cover and have a look at the bigger powerhead fill holes in the chamber to the right of the exhaust line shown in the pic.

[fishfun83]

I have stopped =my brothers C60 from overheating at high RPM by dropping the lower unit, pulling the statcover and stat, hooked up a water hose directly to the water tube heading to power head, turning water wide open letting it flow out everywhere it can, and then shooting compressed air into the water hose off and on .( I just poked a hole in the hose with my small nossel on my air gun, but maybe set up a tee and some valves would work)
lots of stuff came out.
the air and water helps move things around and out.

We ran it up and down the river for 30 minutes with no overheating.

Something to try if you do not want to take it apart right away

Have not tried this yet. Replaced the thernostat and the PSV at the dock just to check things out. This will definitely be my next step. Will pull the boat out of the water in a few days.