50hp 1984 Mercury outboard

My engine was and is running very well but I had water leaking around the number one plus and decided to go ahead and put a cylinder head gasket on before it gets worse and everything has gone wrong..now it's leaking a lot more than before so what I need to know is the thermostat hole at the left of the number one plug can I just plug it and be ok..

I believe that hole is for a temperature warning switch.----Not a good idea to leave that out.-----Did you check the cover plate to see if it is warped ?----Used the correct gasket ?---Used sealer on this gasket ?----Last one I did was no trouble at all.

Thanks for the reply..I have done all the above..one other thing I wanted to ask..I have owned this motor for near 20 years and it wasn't a sensor on it so would it be ok to plug the hole and mount one in another location.. thanks in advance.

Likesilk. I have the same outboard. Mine actually leaked a few years ago. It is a water jacket though, instead of a cylinder head. They make two versions of that gasket, with one being much beefier in terms of the coverage under the jacket. I used sealer with it and haven't had a leak since. I should note that this was the second time I did this. The first time was with the less than beefy gasket. This gasket has slim structures around the plugs. his is where I believe they fail. BTW, I believe thatno water should be coming out of the hole you referenced. Not sure if you installed thetemperature sensor if it would spike the gasket to get a water temp reading or if it reds the heat by conduction.

Ok thanks for the info...I'm getting ready to install the gasket and want to ask if I need to use any type of sealer with it..I have the Quicksilver gasket.. thanks in advance for any help oh I forgot the sensor wasn't on the engine when I purchased it many years ago it only threads doesn't have any water coming through it...it's always been fine just have to make sure it's pumping with a good flow.

Definitely use a sealer along with the gasket.