Volvopenta 4.3 exhaust flap/valve issues

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pentavolvo

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Have a 1997 Celebrity 20 ft bowrider with the 4.3 GS PLKD with a volvo penta sx cobra lowerend

All of a sudden the boat wouldnt start after had been using it for some time. Eventually found water in the left hand side of the block after pulling plugs and getting the water out and figuring out that it was coming in through the exhaust i pulled the exhaust elbows off from the exhaust manifold on both sides and ran the motor and eventually put the elbows back on and went for a long drive to make sure all was well and get the motor to temperature

With both elbows off I see that I am missing a flap on my left hand side since there is somewhat of an indentation from where it would sit and there is one on the other side, my assumption is that water back flowed in since the flap is missing on my one side.

I cant find these anywhere or I am looking in the wrong spot, all the diagrams dont seem to show them

According to every diagram I have seen
parts1.jpg


part 20 is called a bellow and is part number 3863450 if i recall correctly from when I had it apart the flap was actually installed in the exhaust pipe directly below the bellow. Maybe I am wrong, does anyone have any insite is the flap actually part of the bellow or something seperate
 
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pentavolvo

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Re: Volvopenta 4.3 exhaust flap/valve issues

What am I to do to prevent water ingestion then because clearly it was working on my boat since I took water in on the one side without the valve but not on the other side

is there some sort of aftermarket piece I can put in or am I really ok with nothing

thanks
 
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TilliamWe

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Re: Volvopenta 4.3 exhaust flap/valve issues

You may just have a bad manifold on that one side. That's usually how water gets in one side, that manifold is bad.
 
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pentavolvo

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Re: Volvopenta 4.3 exhaust flap/valve issues

by manifold do you mean i would have to put a whole new manifold on?

i will call sierra and see what i can find out

any other ideas
 
Don S

Don S

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Re: Volvopenta 4.3 exhaust flap/valve issues

Are you getting a lot of wave action on the back of your boat while parked?
Was there a lot of weight on that side of the boat and on the back that could make it too low in the water for the riser?
The flapper valve will not seal tight, and even if you find one may not cure your problem.
Could also be a cracked manifold or riser, or bad gasket surfaces.
 
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pentavolvo

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Re: Volvopenta 4.3 exhaust flap/valve issues

Where the boat is parked wave action should be pretty minimal, but im not the one that was out on it when this happened water could have been pretty rough it was the 3rd and the lake was busy.

Regarding it possiably being the manifold or riser etc, i did a compression check and all cylinders are within 10% of eachother. Also I did run the boat after getting the water out for atleast an hour and had no other water issues.

Personally I feel it is a flapper issue since the other side still has a flapper and I didnt have any problems there. Is there another flapper in the lower end by chance that could be missing?

Is it possiable someone makes a bellow with a flapper in it that i could use

thanks
 
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caken

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Re: Volvopenta 4.3 exhaust flap/valve issues

I had the same problem with my boat with the same engine. After 1 year and a lot of money later my mechanics figured out that the height of the risers was not even close to the factory recommended so they changed my risers and manifolds.

After all of that my boat seemed to be running great. I took it out like 10-15 times and no water got in the engine.

Two days ago I was driving it and the engine just died. I tried turning it over a few times and nothing happened. We were towed back to the dock and when I came the next day it turned over and almost started. Then I heard a really loud clanking noise which is what happened all of the other times my started went out.

Is there anything else that can be causing this to happen besides water coming up over the risers? My mechanics also told me that there used to be flaps in my exhaust manifolds but eventually just fell out.
 
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pentavolvo

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Re: Volvopenta 4.3 exhaust flap/valve issues

curious do you know what the proper height of the riser should be

my one valve one passenger side flapper is gone the drivers is still there, personally i am convinced this is my problem but am curious to see what others have to say, i am currently trying to locate a replacement bellow with a flapper in it
 
mtbdudex

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caken

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Re: Volvopenta 4.3 exhaust flap/valve issues

I don't know the height, but will find out tomorrow when I speak with my mechanics.

I did just pull the plugs on mine and there was water in the engine as expected. So even with the highest risers possible water was still able to get in.

I think the flappers are needed to keep the water out. Now where do we find them....
 
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pentavolvo

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Re: Volvopenta 4.3 exhaust flap/valve issues

mtbdudex said:
Timely find, my boat mechanic who just did my 4.3L re-man job stated he found my flapper valves burned and replaced them, now how'd he order the parts if Volvo does not sell them?

He showed me old/burned ones.....

I'll first fwd him the pdf file and then call him.
Click to expand...

let me know when you here
 
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pentavolvo

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Re: Volvopenta 4.3 exhaust flap/valve issues

does any one know if there is a flapper of sorts in the outdrive somewhere?
 
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danmod18

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Re: Volvopenta 4.3 exhaust flap/valve issues

There are a few problems, !st , the risers in most boats are very low but just increaseing the height of the risers alone will not cure the problem of hydro locking the engine( which can destroy an engine) 2nd, the flapper valves that were installed in the Ypipe are prone to failure, when they do, they have a tendancy to block the exhaust port that runs through the center of the propeller when this happens the only exhaust port that is open is the small port at the base of the transom. Having a partially blocked exhaust will cause poor performance and somtimes engine heating, also as the port at the transom is the only exhaust port when stopping theboat the presure that builds up at the transom is enough to push water up and over risers even with the riser extentions added. 3rd, if you find that your flappers are missing you cannot just replace them, you need to be sure that the old ones are not blocking the exhaust at the base of the Y pipe which is where they end up generally., 4th volvo no longer makes the valves available but you can use the one from mercuiser but even those will fail at some point. 5th ,the only sure fix is to run through the transom exhaust bells with external flappers, which is a conversion that I am presently doing on a 97 celebrity with a 4.3 engine that I have just rebuilt due to this problem , the old engine was a complete loss. I hope this post will help others with this problem
 
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