Transom plate

[Alex Smith]

Why would there be silicone filling the hole on the transom plate? I thought that that hole was used to discharge the water from the exhaust cooling.

 

[Bill D]

If you are talking about the exhaust port, the general opinion is that is just overfill from the factory. Nothing to worry about.

 

[Scottintexas]

It's hard to see but are you talking about the hole in the center of the picture above the cable and below the right silver bolt, it's hard for me to see but it looks discolored like it might have silicone on it. If so, it shouldn't. Check out this video from the FAQ from our member Buckbuck at time 2:18 it shows the discharge, The gift that just keeps on giving!
https://jetboaters.net/faq/how-does-the-cooling-water-flow-in-my-yamaha.101/

 

[Alex Smith]

It's hard to see but are you talking about the hole in the center of the picture above the cable and below the right silver bolt, it's hard for me to see but it looks discolored like it might have silicone on it. If so, it shouldn't. Check out this video from the FAQ from our member Buckbuck at time 2:18 it shows the discharge, The gift that just keeps on giving!
https://jetboaters.net/faq/how-does-the-cooling-water-flow-in-my-yamaha.101/

Yes that's what I was referring to. My engine is not one of the m1's but it looks like the same cooling set up. I guess I'll try and cut it out tomorrow. Never noticed it until I was trying to track down a leak today.

 

[itsdgm]

Yes that's what I was referring to. I guess I'll try and cut it out. Never noticed it until I was trying to track down a leak today.

It's normal on the non-ho engines. Mine are both the same.

I believe that the water coming out of the thermostats exits out the through hull plastic fitting just above. Not sure why Yamaha made them different, but I noticed this difference a few years ago when guys posted pump pics of the HO engines.

 

[itsdgm]

Looking at @buckbuck 's video. He describes that as an outlet for the exhaust manifold. The non-ho engines have a different type of exhaust manifold.

 

[buckbuck]

On the HO MR-1's it will have water coming out when you first start the engine. After the thermostat opens water will no longer flow out that hole. I guess you could consider it a pressure relief. Again, this applies only to the HO engine (to the best of my knowledge.)