Need final word on exhaust shutters.

[Fishermark]

I put a new Mercruiser crate engine in my boat last fall - a 2003 5.7 liter engine complete with new exhaust "y" pipe, etc. I have probably 60 or 70 hours on this engine. When I pulled it recently to do some transom work I noticed that the exhaust shutters are already burned and melted! This engine has never overheated and runs fine. I went to the local mercruiser dealer to buy new shutters and was asked if I really wanted them. The consensus of the local mechanics, (and I've talked to several), is that they are unnecessary and it is not uncommon for them to go bad in a short time as mine did.<br /><br />Now, before someone gets too bent out of shape I am not asking if it is okay to put an automobile carb on my motor, etc - and I understand the purpose for the shutters - to keep water from coming back up into the engine through the exhaust. But if they don't last, they aren't exactly doing what they are designed to do! <br /><br />I was blissfully unaware that my shutters were already gone!<br /><br />If I go ahead and replace them, is there something I can do to make them last longer? Remember, this engine has never overheated.

 

[crazy charlie]

Re: Need final word on exhaust shutters.

I would replace them.The part that melts only accounts for a very small part of them.Over 90% of the surface area is metal so they will still do the job of preventing a catastrophe in a certain instance.Charlie

 

[Chris1956]

Re: Need final word on exhaust shutters.

Fishermark, I had the same experience as you. I found the remains of one exhaust shutter in the exhaust passage of my outdrive. The Merc Mechanic did not think they were necessary to replace. He did caution about cutting the throttle quickly, lest water find it's way into the motor. I have not had any problems with water in the engine.

 

[Fishermark]

Re: Need final word on exhaust shutters.

Charlie, on one side, only the rubber had melted, but on the other, pretty much the entire asembly was gone. (By the way, do you go by "Crazy" or "Mr Charlie?" ) <br /><br />Chris, how long have you been without them?

 

[crazy charlie]

Re: Need final word on exhaust shutters.

FM,the few times that I have replaced them only the rubber was gone.If the entire assembly is gone on one I would surely replace it.I have been in a following sea too many times and on occasion had to throttle down immediately because of a crab trap or shallow water,I dont need that hanging over my head.They are there to prevent catastrophe to your motor so in my opinion it is a small price to pay.By the way I like MR. Charlie but usually by the end of the day no doubt I go by Crazy Charlie.Thanks for asking!!!I hope you make the right decision.Charlie

 

[Chris1956]

Re: Need final word on exhaust shutters.

FM - I lost the one shutter at least 4 years ago. I never investigated the other one's condition. I use my boat alot, in all conditions, and have not had a problem.

 

[Fishermark]

Re: Need final word on exhaust shutters.

I really am not opposed to replacing them, IF there was something that could be done to make them last longer...

 

[yoced]

Re: Need final word on exhaust shutters.

Keep water going through your exhaust and they WILL last longer. Surest cause of melted rubber is HEAT.

 

[Fishermark]

Re: Need final word on exhaust shutters.

yoced, I never run my engine without water. So whatever water is designed to go through the manifolds does so. I understand that heat causes the melting, but my point is a simple one - unless I have some defective manifolds, (which is possible I suppose - but again, according to the local mechanics, this is a common problem), then something hasn't been designed well, because everything is new and certainly not clogged with rust yet.

 

[DHPMARINE]

Re: Need final word on exhaust shutters.

fishermark some thoughts and ideas.<br />I've seen many boats with burned out shutters for who knows how long?And long time since I've seen water ingestion on any boat.<br /><br />I've heard some MC's had problems with the water intake hose,in the bell housing,collapsing.I think 1999 units.<br /><br />Also had a customer looking for 'old' exhaust riser gaskets for his big block.Seems they had 4 large oval holes for water passage,and 'new'gaskets have 2,plus 2 small holes.<br /><br />Maybe some engines don't overheat,but run too warm for the shutters?<br />DHP

 

[Fishermark]

Re: Need final word on exhaust shutters.

Maybe some engines don't overheat,but run too warm for the shutters?

DHP - The interesting thing is that this, as mentioned, is a brand new crate engine - complete from the raw water pump to the y pipe. I have a 1.25" thru hull pick up, so it has to be getting PLENTY of water. You would think that Mercruiser would come up with something that would work better and last longer! Oh well, now I'm just venting. <br /><br />A thought just struck me... as this engine is less than a year old, this should be covered under warranty I would think.... I'll have to do some investigating!

 

[achris]

Re: Need final word on exhaust shutters.

FM<br /><br />Need to know which style shutter you have. There are 2 types. Type 'A' is a stainless steel plate with a couple of 'loops' on the edge and a S/S pin through the exhaust pipe and the loops on the shutter plate. Type 'B' is like 2 plates secured to a shaft by rubber that slot into the exhaust pipe. <br /><br />If you have type 'A' don't replace them. My 4.3 had type 'A' and with the constant movement they 'sawed' through the shaft and dropped into the bottom of the 'Y'. One went all the way through and out the prop (I assume), but the other lodged in the 'Y' junction and wore a hole in the pipe. 30 miles out to sea is not a good time to find out you're sinking! <br /><br />Mercury replaced the exhaust 'Y' with the later style under warranty! <br /><br />Chris..............

 

[surfer23505]

Re: Need final word on exhaust shutters.

Chris, that had to suck!

 

[achris]

Re: Need final word on exhaust shutters.

Here's a picture to help explain the different types.<br /><br />

<br /><br />Surfer, Yep, that sucked! Best bilge pump in the world? Scared wife with an ice cream bucket! (Quart size)<br /><br />Chris.........

 

[Fishermark]

Re: Need final word on exhaust shutters.

Hi Chris,<br />I have type "B"

 

[achris]

Re: Need final word on exhaust shutters.

FM,<br /><br />Replace them and make sure you have water flowing out of both risers. Did both shutters burn?<br /><br />Chris...........

 

[Fishermark]

Re: Need final word on exhaust shutters.

One is burned off completely - the other is still complete, but barely.

 

[surfer23505]

Re: Need final word on exhaust shutters.

I dont know that much about shutters, but dont the risers do the exact same thing by keeping water out of the engine?

 

[achris]

Re: Need final word on exhaust shutters.

The risers are more to do with cooling the exhaust gases and getting the 'old' cooling water out of the system. The shutters try to keep water that 'shots' up the exhaust pipe from getting into the manifold, through the risers.<br /><br />Chris............