Exhaust Flappers?

[LinkAmerica.net]

Hello,<br />I have been having an ongoing problem with my 90 OMC Cobra 5.8. I am getting water in the oil. I posted a post a while back and I am back to ask more questions. I have taken the heads off because I thought it could have a busted head gasket. Well, none of the gaskets are broke that I could tell, so I had the heads compression tested, resurfaced and put them back on with new gaskets. The heads checked out ok. I also put a new Intake Manifold on, and Edelbrock Performer because the stock manifold had a crack in it. That apparently was not the problem because it still happens. I notice another interesting thing, it only gets water in the oil if I put it in the water and run it for 20-30 mins. After rebuilding the heads, I put the earmuffs on and ran it for about an hour or so and there was no water that got in the oil. As soon as I put it in the lake, it got oil in it. I don't believe it is a cracked block because if it was, I think it would get water in the oil on the muffs, and I let the engine temp get to operating temp. So I got to thinking and maybe it was getting water in the exhaust when we backed off and made a stop. I took off the risers and looked at the exhaust flappers and they were melted and the seal was messed up. When they were closed, it did not make a seal, the edge was messed up and I could stick a screw driver between that and the pipe. I went to the marine place and they said it was a known problem but mostly happens if someone puts a different engine in the boat because it lowers the manifold closer to the water line. <br /><br />My question is this.<br />Has anyone ever heard of this happening?<br />Am I going to fix the problem with a 15 dollar part after I spent 400 dollars on a new intake and head work?<br />Please help, any info would be great. <br />Again, why would it happen only in the water and not on the muffs?<br />I also figured that in the exhause manifold was cracked, it would get water in on the hose too.<br /><br />Thanks,

 

[Bart Sr.]

Re: Exhaust Flappers?

LinkAmerica.net----There was a huge discussion on this board between Sept. to Dec. 2002 about "water reversion" and "static line". Use the search function at the top of this page using the keyword "static" and check the postings during that time. I'm sure you will learn from those. Welcome to IBoats.

 

[LinkAmerica.net]

Re: Exhaust Flappers?

Well, <br />Just got back from the lake after replacing the flappers. Still getting water in the toil. This time we ran it about 15 miles per hour from the dock and didn't stop for 15 minutes. As we cruised down the lake, I periodically checked the oil to see if it was getting milky. All was fine. Then we stopped, turned the engine off, waited 5 minutes, checked the level again and it was fine. Started it back, checked it again, it was fine. Then we ran it back towards the dock at about 35 mph and 5 minutes later, I checked the oil and it was milky again. Seems like it is only happening when there is a load on it in the lake because I can rev it up hooked to the hose and it does fine for an hour. Could this still be exhaust manifolds or risers? Could there be a crack in the manifolds that only leaks when you put a strain on the engine? Or does anyone think a crack could be in the block and leak only when it has a load? The exhaust manifolds and risers are the only thing that hasen't been checked. I am going to call the marine place tomorrow and see what they charge to do this.<br /><br />Any help, please!<br /><br />Mike

 

[rabidfish]

Re: Exhaust Flappers?

As a dealer for more than 20 years, i can tell you this....<br /><br />It is not uncommon for a small "hairline" crack in the block, to only show itself when the engine is run under load. This creates more heat in the block, even though the gauge may read the same temp. therebye opening the crack. <br /><br />my advice is this... do not try to have it repaired. purchase a marine remanufactured long block. sounds like you have the skills to replace it yourself. <br /><br />after 13 years, it isn't likely that you developed a reversion problem...

 

[mvaughn]

Re: Exhaust Flappers?

Link, <br />What temp is the gauge reading?

 

[LinkAmerica.net]

Re: Exhaust Flappers?

Unfortunatley the temp gauge is not one that has numbers on it so I can't tell what temp it is rising to. It is a standard gauge that has a green section and a little red section at the top. It always stays in the green section, but it does rise and fall as if the thermostat is opening. If there was a crack in the block, would it show if I did a compression test? Because I did one before I did the heads and they all were about 130 +/- 5 on each cylinder. We also had the heads pressure tested and they tested at 45 psi and stayed for an hour. Could there still be a crack in them. Should I test them again and heat them first in an oven? <br /><br />If you say get a rebuilt Marine engine, where do you think I could get on from online? I don't believe any place aroung me is going to have any, but I will check.<br /><br />Thanks,<br />Mike

 

[a.d.mobile]

Re: Exhaust Flappers?

you have a block problem usualy a ford can take a good freezing. why not find a good machine shop and have block replaced using youre crank, rods, cam. they will have to bore and replace pistons i dont think you will find a block with good holes. I do this all the time for people. or find a marine salvage yard they might have a whole engine from a wreck.

 

[LinkAmerica.net]

Re: Exhaust Flappers?

I bought the boat from an old man and I am the 3rd owner. Of course there is no way I can know if it was froze before. One of the exhause manifolds was replaced because it is a different color than the other, 4 freeze plugs were replaced because those are silver and the others are the color of the block, and the freeze plugs in the heads were pushed out but were stoped by the bracket that was in front of them. Also, when I had the heads off, there was water marks in some of the cylinder walls that tells me there was water sitting in there for a while. <br /><br />Mike

 

[rabidfish]

Re: Exhaust Flappers?

From your description you definately have a cracked block. Sounds like someone may have even known it was frozen. <br /><br />As for where to find one...<br /><br />Try Jasper engines & transmisions. They do a huge marine business. You may even find a Jasper dealer close to you. ( i dont use them personally, but they are a reputable business )<br />( www.jasperengines.com )Make certain you are getting a Marine engine that matches yours.

 

[Trent]

Re: Exhaust Flappers?

Before you start yanking the engine out. Have the manifolds and risers pressure checked. Most times water intrusion is due to a bad riser or manifold.

 

[a.d.mobile]

Re: Exhaust Flappers?

broke manifolds (exaust) will not put water in the crankcase they will put in the cyl after engine is shut down.

 

[mvaughn]

Re: Exhaust Flappers?

It does sound like the engine was froze, and a crack is possible. I had a similar problem this spring.<br />search for "water in the oil" May 09 <br />Hope it helps, good luck!

 

[LinkAmerica.net]

Re: Exhaust Flappers?

^

 

[akriverrat]

Re: Exhaust Flappers?

cracked, rusted through, leaking risers/manifolds will cause water in crank. it gets into cylinder and leaks past the rings. it can even happen on a running engine.

 

[a.d.mobile]

Re: Exhaust Flappers?

Yes i have seen water in cyl's from manifolds or risers but the engine wont run good enough to plane the boat when this is happening. been doing I.O engine work in dealers for 10 years and on my own for 8 and have only seen this 1 time engines do not run very well on water. I guess salt water areas would see this more than me in mi.

 

[akriverrat]

Re: Exhaust Flappers?

newer (roller cam) gms are running on the ragged edge of too much cam overlap and reversion. if water is getting into exhaust stream sooner than it should through a leak it makes it much more likely. and they can perform flawlessly while doing it. a.d. mobile, saltwater areas see a lot of bad manifolds. and how many boats on the water on any given day would benifit from your services? better than half would be my guess.

 

[Trent]

Re: Exhaust Flappers?

Saltwater engines...The manifolds and risers should be changed every four to five years!! If not your in trouble. Guess a.d. mobile is just a freshwater guy?

 

[biloxiriver]

Re: Exhaust Flappers?

Trent, or anybody else, when you say replace the manifolds and risers every 4 or 5 years, are you just talking about the exhaust manifold or the intake as well?? I have been running I/O's in salt water for many years and have only had 1 (the one I have now) with a exhaust manifold crack. Just lucky?????

 

[Trent]

Re: Exhaust Flappers?

Man your own borrowed time. Just the manifold and riser. Not the intake.