Hole in y-manifold casting

[JHinMT]

Backstory - We have a early 90's merc i/o boat. 4.3l alpha one gen 2 outdrive. It's been in storage for 10 years (life), last time we used it it was leaking badly but I couldn't figure out where the water was coming from.

This spring I finally had time and inclination to clean up the boat and get it back on the water. Spent some time cleaning things up, replaced the impeller and a hose that looked suspicious. Ran the motor several times on muffs, everything looked good, but no sign of the leak.

So, yesterday we took it to the lake with the engine covers removed so we could see if any water was coming in. It was, about like a kitchen faucet 1/2 open. I got my camera in there and got a video, today I got in there with lights and a camera and found there is a nice hole in the y casting almost directly under the drive shaft. Looks like it was punched with a cold chisel from the inside. In the attached image hole is center top.

Options? I presume I'll have to pull the engine to even get to the thing?

 

[Bondo]

Ayuh,..... Welcome Aboard,..... If the shutters got burnt up from a lack of water flow, the burnt bits can eat a hole in the y-pipe,.....

'n, Ya, the drive comes off, 'n then the motor comes out, to change the y-pipe,.....

 

[JHinMT]

Thanks. I figured it was easy. Step 1, pull outdrive, step 2 pull motor, step 3 pull y-pipe.

I was wondering if blown flappers could cause this. There are metal shavings or burrs around the hole, it just doesn't look like a weak spot in the casting.

 

[JHinMT]

Pulled exhaust tubes and elbow on port side. There is no flapper at the top of the y-tube. I believe I've read there was an early version with the water shutter down near the transom instead of up at the top of the y tube (?). I'll pull the other side shortly.

 

[Bondo]

Pulled exhaust tubes and elbow on port side. There is no flapper at the top of the y-tube. I believe I've read there was an early version with the water shutter down near the transom instead of up at the top of the y tube (?). I'll pull the other side shortly.

Ayuh,.... That early version was 1970 something,.....

Yer shutters belong at the top of the y-pipe,....

 

[JHinMT]

Yup. Pulled other side. No flapper there either, but I did find the holes on each side of the y- pipe for the pivot pin, then looked and found them on the port side as well. No trace of the flappers themselves. Outdrive next I guess and see if parts and pieces are stuck there someplace.

 

[JHinMT]

With the outdrive off I can see part of one flapper way back in there, probably about where the hole is. No signs of any other parts and pieces.

 

[dubs283]

With the outdrive off I can see part of one flapper way back in there, probably about where the hole is. No signs of any other parts and pieces.

could be the cause of the hole

check the exhaust passage on the drive for other flapper parts/pieces. i've found them wedged in the carrier assy from time to time

 

[JHinMT]

I worked the port side flapper out to the end of the gimbal exhaust port but I Can't get it around the upper shift shaft that neatly bisect the exhaust. I loosened the set screw on the head of the shift lever shaft but I cant turn the shaft. Is there a trick or is it just stuck?

 

[JHinMT]

Nevermind, I managed to fold the flapper with a couple pair of needlenose pliers and get it out. I also found the starboard side flapper and got it out. Only thing missing, I think, is the pins the flappers mount to.