Inspect exhaust shutters while in the water? Just making sure...

Goodman98155

Cadet
Joined
Jan 26, 2019
Messages
19
If I remove the exhaust elbows and/or risers to get at the top of the y-pipe while the boat is in the water, am I going to sink my boat?!

It doesn't seem like it would but of course I have to ask.

I have a 1996 Mercruiser 5.7L in a 26' Bayliner. It has sea water cooling for the exhaust, coming from a heat exchanger for the engine cooling. Due to some previous overheating, I have been strongly advised by folks on this forum to inspect/replace the exhaust shutters. The engine may have been overheating at idle for quite a while before I bought it.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
If you have full closed cooling, and you need to remove the exhaust elbows, you'll need to drain the closed cooling system first... (gaskets under the elbows are the 'break point' between the closed cooling and the rest of the world.)

If you are unsure of whether the top of the y-pipe is above or below the water line, get a long piece of clear hose and fill it with water. Have one end in the ocean and the other end up next to the y-pipe. The water level in the hose will be the water level in the y-pipe.

Chris......
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,286
Sound advice above from Chris. It all depends on your boat and how it sits in the water. Most of the boats I’ve had would see the water level at around the shutter level. Maybe a few inches below the top of the cow horn inlets from the exhaust
 

Bondo

Moderator
Staff member
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Apr 17, 2002
Messages
70,468
Most of the boats I’ve had would see the water level at around the shutter level.

Ayuh,..... Ditto,...... Right at, or very close to the top of the y-pipe,.....
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,802
If someone pulls into your marina and makes big waves this could turn out to not be a good idea. If the boat is moored/slipped all the time you should schedule a haul out and check everything that is questionable at the same time. I thought of changing an exhaust manifold on the mooring once.....only though of it because if anything goes wrong (ie broken bolt, can't get it back together, etc) when you have it half apart, and you haven't fabbed up a way to keep water in the Y pipe it could turn out to be a very bad idea. Do it on land!
 

Goodman98155

Cadet
Joined
Jan 26, 2019
Messages
19
I went ahead and carefully removed the elbow on the port side. Didn't have to remove the riser thankfully. Turns out the water line was about 2.5 inches below the top of the y-pipe. Lacking clear tubing, I did some careful measuring and used the location of a through-bolted piece of hardware to verify. The shutters were completely gone lol. Just the metal pin that they used to be connected to. Thanks for all of the advice!
 
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