Machinist (or anyone) - What is this small hole in the cylinder water passage - 15hp?

[WA-Newb]

I just notice you were posting here LeeRoy....I am the one who has emailed you a couple of times now recently from Washington state with the over heating 15.

I thought I would post this here instead of emailing you since it might help someone in the future.

While I had the head pulled off this 1991 Evinrude 15 I noticed some silicone (I think) coming out of a small hole in the water passage surrounding the pistons. Pointed to it in photo.


I was hoping you (or someone) could tell me what this hole is for...and where this white worm (silicone?) could have come from?

Sure hope I did the right thing by pulling it out with tweezers but really want to know more about it in case there is more etc. that i should go find.

By the way if anyone owns an Evinrude 9.9 or 15 with issues and hasn't checked LeeroysRamblings website yet then you are missing out. It's a must stop for troubleshooting these motors.

 

[raczekp1]

Re: Machinist (or anyone) - What is this small hole in the cylinder water passage - 1

at this side where pee hole elbow is located is water jacket,

at upper part of this water jacket is 1 hole(only one, dia 5 mm) leading into cylinder cooling chamber letting to water flow

maybe someone driled second hole to fiil water much faster into cylinder chamber

 

[WA-Newb]

Re: Machinist (or anyone) - What is this small hole in the cylinder water passage - 1

Any idea what the previous owner could have used the silicone on that I found in there?
I would like to know some possibilities is all, but it would have to be something before that hole since it was trying to make it's way out...I am guessing.
Not sure where that hole leads really as this was my first time removing a head.
Thanks

 

[the machinist]

Re: Machinist (or anyone) - What is this small hole in the cylinder water passage - 1

That is a factory drilled hole. Pull the sideplate cover gasket off & look into the water passage at that location, you will see a hole thru into the water jacket around the cylinder walls in that location. Not really sure why it is there UNLESS it is to ensure there is no trapped air inside the block, creating a hot spot.

I suspect someone saw the hole & tried to plug it off with silicone.

 

[TrueNorthist]

Re: Machinist (or anyone) - What is this small hole in the cylinder water passage - 1

Could also just be a loose bit of silicone that found a place to wedge itself. Lots of folks use way too much RTV when assembling thermostats etc.

 

[the machinist]

Re: Machinist (or anyone) - What is this small hole in the cylinder water passage - 1

I don't think so because you can see the edge of the hole in the photo. I was not sure myself until I pulled the cover gasket off a old block in my junk pile.

 

[WA-Newb]

Re: Machinist (or anyone) - What is this small hole in the cylinder water passage - 1

Thanks to both of you..I will pull the side cover off at some point and have a look to see if there is anymore silicone in there. I still have to deal with fixing the "correct' stripped out head bolt so will do that first.