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Fritzdog

Hydrolocking on 2007 247 When I turn the engine off and it is weighted down

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Fritzdog

I have a (new to me) 2007 247 LSV with the hammerhead 383 and I am getting a water locking problem that is driving me crazy... It happened twice and the second time it trashed the starter motor. While replacing it the mechanic said there was a bunch of water in the spark plug cylinders ... He suggested I not turn the boat off while we are loaded down and that seems to work ok.... However, I would like to see if anyone has a better fix to the exhaust system???? I am thinking there is a one way valve that could be mounted between the manifold and the exhaust pipe. Thoughts?

Thanks

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85 Barefoot

Eh, I don't see how water is making it up the exhaust system. However, I'd bet it IS making into the cylinders due to a bad gasket between the risers and exhaust manifolds which, if breakdown there occurs, can allow coolant water in the riser to get into the manifold and easily make it into the cylinder.

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UWSkier

Eh, I don't see how water is making it up the exhaust system. However, I'd bet it IS making into the cylinders due to a bad gasket between the risers and exhaust manifolds which, if breakdown there occurs, can allow coolant water in the riser to get into the manifold and easily make it into the cylinder.

Agreed. Unless you're slammed to the point the manifold curve is below the water line in which case we need pics!

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Bill_AirJunky

Eh, I don't see how water is making it up the exhaust system.

Bad/missing exhaust flaps, sacked out & chopping the throttle quicky when a rider goes down?

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85 Barefoot

Bad/missing exhaust flaps, sacked out & chopping the throttle quicky when a rider goes down?

If it hydrolocked immediately AFTER cutting throttle that's plausible. But even if water made it all the way up there, in a matter of seconds its pushed right back out. although OP hasn't specifically said, it sure sounds as if its hydrolocked AFTER shutting it down. Making the riser water jacket breach even more likely. I've never had this exact issue or anything :innocent:

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MadMan

Bad/missing exhaust flaps, sacked out & chopping the throttle quicky when a rider goes down?

Agree, this is the reason for flaps, when that wave hits the transom.

It seems more prevalent with direct drives though. The water has a straighter shot.

Edited by MadMan

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85 Barefoot

Agree, this is the reason for flaps, when that wave hits the transom.

It seems more prevalent with direct drives though. The water has a straighter shot.

Whats "more prevalent"? Water getting "pushed" up through the exhaust baffles, up the exhaust hose, up the risers and down into the manifold? Can you actually cite an example of that happening?

OP, can you take a picture of your risers? they one piece? if so, they toss my thoery out the window, BUT...is there any water in your oil?

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MadMan

Whats "more prevalent"? Water getting "pushed" up through the exhaust baffles, up the exhaust hose, up the risers and down into the manifold? Can you actually cite an example of that happening?

I never argue back and forth on forums.

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scottnance

does it happen on both engine banks or just one? I have to agree that its probably a faulty elbow to manifold gasket or a crack in the jacket to exhaust in the elbow.

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oldjeep

Whats "more prevalent"? Water getting "pushed" up through the exhaust baffles, up the exhaust hose, up the risers and down into the manifold? Can you actually cite an example of that happening?

?

Seems to me that someone on this forum did that exact thing to a brand new MB last year.

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shawndoggy

Seems to me that someone on this forum did that exact thing to a brand new MB last year.

LOL if you mean me, it weren't. Mine locked on plane while under power, not after a throttle chop. Also my old MB had a single 4" straight pipe (no flapper) and no muffler. you could stick your arm up to the elbow right through the transom. that 4" pipe went straight to the (PCM) exhaust dump. If it were going to hydrolock on the basis of coming off plane on a throttle chop (a) it was totally a great candidate for the theory, and (b) fact that it never actually did lock up that way suggests the theory has some holes. At the time we also had an FAE mounted, which would also undercut the throttle chop lock potential, even though I know that's not what happened to me.

how it happened remains a mystery. I sortof suspect it may have been a loose or leaking raw water crossover hose that put water down the air intake, but I don't know for sure. I went through and removed and tightened every hose and water connection after that. Never did it again in 30+ more hours of operation, and I haven't heard about the issue happening in the motherland.

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Fritzdog

I think I found the culprit.... I pulled the boat and checked out the exhaust system. It doesn't have any visible flaps!!! Was this stock or some sort of owner customization I wonder? I am trying to attach a picture.... That said, I do chop the throttle back when someone falls and back up to let the wave clear past me before I turn. When the engine is going , I don't have a problem, but when I turn it off... Then water might back up and over the manifold and cause the problem.

Thanks all...

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Fritzdog

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Bill_AirJunky

Yep, thats it. Combined with the fast stop, backing up & that your probably weighted pretty heavy......

Wasn't there another member here that turned down exhaust & decided to run flaps too? Supposedly you don't need flaps with turn downs. But sure seems like an issue to me.

Edited by Bill_AirJunky

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shawndoggy

those are the silent tips. https://www.bakesonline.com/detail.aspx?ID=756

no flappers required. You are probably back to 85's hypothesis of leakdown through the risers or a head gasket issue.

This is a good read on what to do when it happens and how to correct the problem: http://www.marinemechanic.com/merc/distributors/mercurymarine/sterndrive/waterinengine.PDF

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shawndoggy

Yep, thats it. Combined with the fast stop, backing up & that your probably weighted pretty heavy......

Wasn't there another member here that turned down exhaust & decided to run flaps too?

whut? If those silent tips were a problem it would seem like half the new boats that come off the assembly line every year (with silent tips and without flappers) would have this issue.

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grandude

2007 Hammerhead would be one piece aluminum manifolds (unless they have been replaced) so a leaking riser is unlikely. Just a thought, have you ever tried running the boat without ballast to see if you still take on water? If it's a manifold issue, you would get water in the cylinder even running it on a hose.

Although you should have flappers if your exhaust are not the turned down type, you would have to really have the boat slammed with weight to get the water up thru the muffler. I would consider running it on a hose for a while and then shutting it off and sit a few then pull the plug on the suspect cylinder.

Possibly consider doing a compression check to rule out a bad head gasket or head. Not knowing how long you have owned it and how much you know about the boat besides your current dilemma its hard to say what to do first besides say try something different than running it the same way to see if it happens again.

Pics posted after the post. No flappers needed on these.

Edited by grandude

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CTSunsetter

Are you getting water on both sides or one side only? It could be a hairline crack in the manifold. Buddy just had that problem with his Merc I/O this season. Ran the boat a bunch of day trips with no problem, but it wasn't until the boat was in the water overnight the problem showed up.

Edited by CTSunsetter

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85 Barefoot

2007 Hammerhead would be one piece aluminum manifolds (unless they have been replaced) so a leaking riser is unlikely. Just a thought, have you ever tried running the boat without ballast to see if you still take on water? If it's a manifold issue, you would get water in the cylinder even running it on a hose.

Although you should have flappers if your exhaust are not the turned down type, you would have to really have the boat slammed with weight to get the water up thru the muffler. I would consider running it on a hose for a while and then shutting it off and sit a few then pull the plug on the suspect cylinder.

Possibly consider doing a compression check to rule out a bad head gasket or head. Not knowing how long you have owned it and how much you know about the boat besides your current dilemma its hard to say what to do first besides say try something different than running it the same way to see if it happens again.

Pics posted after the post. No flappers needed on these.

OP, can you take a picture of your risers? they one piece? if so, they toss my thoery out the window, BUT...is there any water in your oil?

Whew, I'm glad I provided my caveat! Thanks for confirming grandude.

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85 Barefoot

I never argue back and forth on forums.

A simple yes or no isn't arguing. Either way, STE had no flappers and were factory option.

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Fritzdog

The problem only seems to happen when I turn the engine off... No problems yesterday and I ran it for fours straight. Is it worthwhile switching the "quite" pipes to the flappers? The water was in the first two of the cylinders and not the third. Thank god, it didn't seem to go farther as the other plugs looked like a hassle to access. I don't see any cracks in the aluminum manifolds but will show all of these comments to my mechanical bud who is surfing with me this morning. Regarding the "slamming " of the boat, it was at least six inches below the stock fuel vent... So nothing like some of the loads I have read about. I have only had the boat for about a month although, I had compression checks done before I purchased it and they came out strong.

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oldjeep

The problem only seems to happen when I turn the engine off... No problems yesterday and I ran it for fours straight. Is it worthwhile switching the "quite" pipes to the flappers? The water was in the first two of the cylinders and not the third. Thank god, it didn't seem to go farther as the other plugs looked like a hassle to access. I don't see any cracks in the aluminum manifolds but will show all of these comments to my mechanical bud who is surfing with me this morning. Regarding the "slamming " of the boat, it was at least six inches below the stock fuel vent... So nothing like some of the loads I have read about. I have only had the boat for about a month although, I had compression checks done before I purchased it and they came out strong.

Maybe stop shutting it off until your wave passes you.

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shawndoggy

Maybe stop shutting it off until your wave passes you.

see that's the other part of the "water up the exhaust" theory that I don't buy. If this is happening while engaged in watersports, does anyone drop a rider, throttle back and immediately shut down? Wouldn't that leave the rider "back there somewhere," without being picked up? I 'spose it's possible you drop the rider and make a crazy power turn to go get them?

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oldjeep

see that's the other part of the "water up the exhaust" theory that I don't buy. If this is happening while engaged in watersports, does anyone drop a rider, throttle back and immediately shut down? Wouldn't that leave the rider "back there somewhere," without being picked up? I 'spose it's possible you drop the rider and make a crazy power turn to go get them?

Aren't they standing like 6 feet behind the boat when surfing?

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