Need help with sterndrive parts

[Ed Dickenson]

First timer here. Go easy on me.
I was changing out the impeller on my Mercruiser Alpha 1 Gen II. I figured it seemed simple enough to do on my own. When I dropped the lower unit, these two pieces of metal fell to the ground. (See pics). I did not notice where they fell from. Semi-circle metal plates. For the life of me I can find out what they are or where they belong. I cant find them on any diagram. The only place that they sort of fit (see Pics) doesnt make sense and they wont allow the top and lower unit to seal when connected.
I tried putting the lower unit back after replacing the impeller without the metal plates, but either the plates are important, or I messed up something because the engine began to overheat when testing. I took the lower unit back off to confirm the correct installation of the impeller and it all seems good, so maybe the metal plates are important?
Can anyone set me straight with this?

 

[alldodge]

Howdy
Your file size is huge, use reduced resolution for pics if you can

The metal pieces are the exhaust flappers. What motor are you working on and serial numbers are best?

 

[Eric 3.7LX Alpha 1]

Like Alldodge mentioned, those are your exhaust shutters. They got destroyed from an overheat, or running the engine on land without water connected. They are normally covered in rubber. They help protect the motor from ingesting water backwards from the exhaust when the motor is off.

 

[Ed Dickenson]

Howdy
Your file size is huge, use reduced resolution for pics if you can

The metal pieces are the exhaust flappers. What motor are you working on and serial numbers are best?
View attachment 346830

Thank you!!! I made the pics smaller.
Yes that is exactly what they are. I bet the other piece(s) are stuck somewhere and might be blocking the exhaust.
I wont have the serial# till tomorrow, but the engine is a 2005 Mercruiser 3.0.
I got the boat in 2010 and I have always felt it was sluggish. Based on all the other surprises I have had through the years, I bet the flapper got cooked before and has been bouncing around inside there since I've had the boat. I didn't need to change the impeller except for preventative measures, but I guess I'm glad I did.

 

[Ed Dickenson]

Like Alldodge mentioned, those are your exhaust shutters. They got destroyed from an overheat, or running the engine on land without water connected. They are normally covered in rubber. They help protect the motor from ingesting water backwards from the exhaust when the motor is off.

Thank you! Yes, that is definitely what they are. I never thought to look at parts beyond the sterndrive

 

[alldodge]

Just guessing but the shutters are item 6 and have to remove the elbow to get at it. Can also look down to see if other items are there

https://www.mercruiserparts.com/bam/subassembly/30906/11669/190

 

[poconojoe]

I would try and make sure there are not any other parts blocking or partially blocking the exhaust. You don't want another overheat situation.

Those two metal pieces make up one shutter assembly (minus the burnt rubber parts).
If I'm correct, your engine only has one exhaust, therefore both metal pieces are accounted for. But...who knows if they were ever replaced in the past and previous parts are causing a blockage.

 

[Ed Dickenson]

Just guessing but the shutters are item 6 and have to remove the elbow to get at it. Can also look down to see if other items are there

https://www.mercruiserparts.com/bam/subassembly/30906/11669/190

Thank you! Got em ordered!

 

[Ed Dickenson]

I would try and make sure there are not any other parts blocking or partially blocking the exhaust. You don't want another overheat situation.

Those two metal pieces make up one shutter assembly (minus the burnt rubber parts).
If I'm correct, your engine only has one exhaust, therefore both metal pieces are accounted for. But...who knows if they were ever replaced in the past and previous parts are causing a blockage.

Thank you! I think I got the pieces. Found the hinge pin and a roll pin. I suppose all that would be left was the rubber, which is long gone I guess.
Relating to the flapper disintegrating is there anything else I should look for that might be affected? Im pretty knowledgeable about engines and maintenance but sterndrives are foreign to me. I read about the gimble bearing going bad and such. Is pulling the top portion of the drive off something I need to do to check it out?

 

[alldodge]

Did you look down inside the exhaust tube to see if its clear?

Every year its best to pull the drive, check gimbal bearing and also alignment.
Bearing is checked by putting you fingers in the bearing and turning. It should feel smooth as silk.

Alignment needs and alignment bar to check

 

[Eric 3.7LX Alpha 1]

Thank you! I think I got the pieces. Found the hinge pin and a roll pin. I suppose all that would be left was the rubber, which is long gone I guess.
Relating to the flapper disintegrating is there anything else I should look for that might be affected? Im pretty knowledgeable about engines and maintenance but sterndrives are foreign to me. I read about the gimble bearing going bad and such. Is pulling the top portion of the drive off something I need to do to check it out?

Yes, you have to remove the drive off the boat to inspect the gimbal bearing. You should also check engine alignment using an alignment tool, and while it is off, you can grease the gimbal bearing and universal joints.

 

[Scott06]

Thank you! I think I got the pieces. Found the hinge pin and a roll pin. I suppose all that would be left was the rubber, which is long gone I guess.
Relating to the flapper disintegrating is there anything else I should look for that might be affected? Im pretty knowledgeable about engines and maintenance but sterndrives are foreign to me. I read about the gimble bearing going bad and such. Is pulling the top portion of the drive off something I need to do to check it out?

They can get damaged during and over heat and fail. Look athe the rubber boots connecting the exhaust elbow and pipes they usually get baked and the plastic components and water tube that connect to the impeller. All thes plastic items are exposed to the exhaust and will melt if water flow into the exhaust stream in reduced .

 

[poconojoe]

They can get damaged during and over heat and fail. Look athe the rubber boots connecting the exhaust elbow and pipes they usually get baked and the plastic components and water tube that connect to the impeller. All thes plastic items are exposed to the exhaust and will melt if water flow into the exhaust stream in reduced .

Good points!
Definately check the water tube.
A previous owner of my boat (4.3 Mercruiser) must have overheated at some point.
I'm guessing it wasn't too bad of an overheat. All the rubber couplings on the exhaust were fine, it was just the shutters and water tube.

I also found shutter parts when I changed my impeller and that plastic water tube guide thing was black and melted.

Oh, for me, the hardest part of replacing the shutters was finding the correct ones!