Anyone know what this is for?

[steriosm88]

We just removed the outdrive from our 79 fiberglass boat. It has a 120 hp Mercruiser in it with a Merc out drive. These two parts were sitting in the exhaust port.
http://i123.photobucket.com/albums/o316/sterios/exhaustflaps.jpg
The Merc has popped it's frost plug so we are in the process of removing the engine to replace it. Can you buy expandable plugs for these like you can for cars? The ones with a bolt through them you just tuck in the hole and tighten with a wrench. THanks

 

[Bt Doctur]

Re: Anyone know what this is for?

To make sure your block is actually cracked, Yes.
winterizing was not done./ done properly and freezing water caused the plug to back out.99.9% of the time ,the block also suffered damage.

 

[steriosm88]

Re: Anyone know what this is for?

Yes we figured that. Any idea what that thing is in the pick though?

 

[Don S]

Re: Anyone know what this is for?

Old burned out exhaust shutter. (aka exhaust flapper)

 

[Anchor Management 1]

Re: Anyone know what this is for?

Old exhaust flappers

 

[steriosm88]

Re: Anyone know what this is for?

Exhaust flappers eh? Do I really need them? They look like they were held in place with roofing tar. Thanks

 

[Don S]

Re: Anyone know what this is for?

Exhaust flappers eh? Do I really need them? They look like they were held in place with roofing tar. Thanks

They used to have a rubber coating till it got burned off due to lack of water flow. Usually caused by a raw water pump that was never replaced till it failed and caused other problems.

Do you need them ...... YES!

 

[steriosm88]

Re: Anyone know what this is for?

So what do they do other than flap in the exhaust stream? Are they like a screen to keep out small fishies?? What will happen if we just leave them out since they look like they've been broken for awhile anyways? I'm guessing I should get the owner to look at the impellor too then eh? Thanks

 

[cr2k]

Re: Anyone know what this is for?

They act as a check valve and keep water from entering the engine and warping hot things and cracking heads and stuff.

Problems I've seen is the SS pin laying in the bottom of the exhaust tube and vibrating through the aluminum there by leaking exhaust AND water in to the bilge. But this takes a lot of neglect to happen.

they are found in the exhaust tube that goes to the drive at the upper end where the rubber boots clamp on. You will most likely have to pull your elbows to replace them. Then you can see if the pin is there and if not maybe go fishing with a grabber.

 

[steriosm88]

Re: Anyone know what this is for?

Thanks for the great info guys. bought the parts today and should have it all put together this weekend. Neighbour is gonna be happy happy happy.