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Dustin_360

Water Reversion, Motor Rebuild, Firebird Lake (salt water), Please Help

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Dustin_360

I have an 04 VLX with a monsoon 340. The engine has 450 hours. The engine has never overheated that I’m aware of (I’m driving the boat most of the time). I was having trouble with the motor running rough about a month ago. I did a compression test and found cylinders 3,4 and 5 all had low compression. I also noticed cylinder 4 had a slight bit of water on the plug after having running the boat in my driveway with the hose hooked up to it. I should mention I thoroughly flush the motor with fresh water after running at firebird.

I took the boat to Paradise Water Sports. They did a leak down test and tried to asses the severity of the problem. It sounds like they were pretty busy over there and didn’t want to tackle a job this big. Paradise referred me to Loyd’s marine to have the engine rebuilt.

Vince, one of the mechanics at Loyds marine had the engine partially torn down when I came by this afternoon. Vince seemed pretty knowledgeable and said he thought the failure had been caused by reversion. He pointed out the corrosion on the exhaust ports of the heads and in the exhaust manifold. You could see where it looked like water was somehow getting in there. Under normal circumstances this isn’t a problem (reversion) but the water a firebird is very salty.

It sounded like the type of reversion the mechanic was talking about is caused from the boat being overloaded… I normally run the boat with stock ballast (1000lbs), 400lbs up front, 400lbs on the back seat, wedge, plus 2-5 people in the boat including me. Firebird is more buoyant than freshwater so when sitting in the water with all this weight the swim deck still is just barely touching the water. I’m just not sure the amount of weight I run could be the culprit. It doesn’t seem like the back end is low enough in the water to get water over the risers and into the motor.

I was reading online that if you idle a thru hull exhausted boat for extended periods water can make it’s way to the valves due to negative exhaust pulses (reversion). The pulses are caused by valve overlap and little water droplets are pulled back toward the port.

In any case I’m just trying to figure out how the water got to the valves/head and how to prevent it. The mechanic was familiar with the water at firebird and said it’s hard on motors. It seems to me if any water from firebird gets on the valves again it’s only a matter of time before this happens again. I will call my dealer tomorrow and see what they say but still was wondering if anyone had any experience with this.

Any suggestion on how to prevent this? Anyone with any firebird experience out there?

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Dustin_360

I don't know yet if any of the heads are cracked (I'm guessing not). Sounded like the heads are going to need the valve seats redone at a minimum due to the salt water. The mechanic didn't have the heads off yet when I went down there. I should know in a few days.

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99response

That is not "normal" for a boat to take water up the exhaust, seems like you were hit with a case of bad luck!

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wienrdog

One of the things that can happen in salt water is corrosion of the passages & rust thru of the risers - which have water running through them. If you got a pin hole into the riser or a gasket gave way, you can get water from the riser jackets into the engine - sometime enough to hydrolock the engine. That's one of the reasons salt water is considered a 'bad' thing when buying a used boat.

Others should speak up, but one option prevent more damage in the future would be a 'closed cooling' system. I quoted closed because it uses anti-freeze in the engine and a raw-water heat exchanger to cool the anti-freeze - similar to a radiator. Not sure if the raw water still goes to/thru the risers though or just into the exhaust past the risers.

Best of luck with the repairs.

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jgouveia3
One of the things that can happen in salt water is corrosion of the passages & rust thru of the risers - which have water running through them. If you got a pin hole into the riser or a gasket gave way, you can get water from the riser jackets into the engine - sometime enough to hydrolock the engine. That's one of the reasons salt water is considered a 'bad' thing when buying a used boat.

Others should speak up, but one option prevent more damage in the future would be a 'closed cooling' system. I quoted closed because it uses anti-freeze in the engine and a raw-water heat exchanger to cool the anti-freeze - similar to a radiator. Not sure if the raw water still goes to/thru the risers though or just into the exhaust past the risers.

Best of luck with the repairs.

you are right about the heat exchanger, but the antifreeze only passes through internal engine components. So you still need to keep an eye on risers and manifolds, since malibu's (at least older ones, not sure about the newest ones) used what is called a half loop system. Raw water (salt) still passes through the risers and manifolds. I just replaced those after 7 seasons as one of my risers had a small hole (the riser itself basically becomes blocked, and pops a hole).

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99response

Weren't the 04 EXT manifolds the ones with the salt/brackish water corrosion issues?

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Dustin_360

Yes I believe so... The one piece aluminum ones correct... The plugs are welded on so they can get the sand out after casting. I believe the plugs are the first thing to go normaly but these are on the outside of the manifold.

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Dustin_360
Yes I believe so... The one piece aluminum ones correct... The plugs are welded on so they can get the sand out after casting. I believe the plugs are the first thing to go normaly but these are on the outside of the manifold.

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Dustin_360

I remember seeing the manifolds (risers) at the shop while they were off my boat. I don’t recall seeing a way for water to get in the engine if the gaskets failed between the head and the manifold. Can anyone confirm that design on these manifolds? I believe the water that cools the manifold comes in through the bottom of the manifold and exits the top of the manifold on the inside near where the exhaust hoses connect. If this is the case I don't think the gasket could cause the issue.

The mechanic said he would check the inside of the manifold for leaks before he re-installs it, (I think he is going to fill it with water to check). Wish they could be magnafluxed but the manifolds are aluminum so I guess this won't work. I hope filling with water is adequate. I'm not sure there is a way to pressure test the inside of the manifolds but that would make me feel a bit better. I just wouldn’t want to miss something like a pinhole because there is no pressure.

When I get the boat back I will probably run it at regular lake first then pull the manifolds off at the end of the day and check for evidence of water getting in near the head. I will probably do this for a while until I’m a bit more confident no water is getting back toward the motor. I wish there was an easier way but I’m not aware of one. I don’t want to have these troubles again.

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Bill_AirJunky

What about bad exhaust flaps? I'm not sure if the water could make it that far back up the exhaust or not.

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Dustin_360

I have the turn down exhaust on my boat so there are no flaps. Seems like the type with the flaps could be a bit better for preventing water from rushing back after coming off plane. Also I heard the flaps mainly help with the boat if it diesels so water isn't sucked into the exhaust.

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jgouveia3
I remember seeing the manifolds (risers) at the shop while they were off my boat. I don’t recall seeing a way for water to get in the engine if the gaskets failed between the head and the manifold. Can anyone confirm that design on these manifolds? I believe the water that cools the manifold comes in through the bottom of the manifold and exits the top of the manifold on the inside near where the exhaust hoses connect. If this is the case I don't think the gasket could cause the issue.

The mechanic said he would check the inside of the manifold for leaks before he re-installs it, (I think he is going to fill it with water to check). Wish they could be magnafluxed but the manifolds are aluminum so I guess this won't work. I hope filling with water is adequate. I'm not sure there is a way to pressure test the inside of the manifolds but that would make me feel a bit better. I just wouldn’t want to miss something like a pinhole because there is no pressure.

When I get the boat back I will probably run it at regular lake first then pull the manifolds off at the end of the day and check for evidence of water getting in near the head. I will probably do this for a while until I’m a bit more confident no water is getting back toward the motor. I wish there was an easier way but I’m not aware of one. I don’t want to have these troubles again.

you will actually hear a pinhole when it first happens. this happened to me on my riser. i could hear what i thought was a tapping noise, and i was really concerned, so as i was trying to find the tapping, i reached behind the riser, and felt the air, and within a few minutes, it popped and water started coming out.

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hawaiianstyln

sucks Dustin... :(

I ran my 04 VLX in Hawaii for a year before I brought it out here. I loaded it down big time and ran it 4-5 times a week in the salt (Oahu water ski club). However, I have a different flush kit than others (MST Guardian) and I truly believe this helped relieve the vulnerability of corrosion while I had it in the water. My engine has been broken down since i've been here and can't find a lick of corrosion anywhere on the outside of the engine or internal (my fault with a cracked head). I sprayed a can of WD40 or T-9 Boeshield on the engine everytime I was done.

Anyways, I know that doesn't help you. I hope it works out for you.

I guess I thought they told everyone to go to Bergeron Marine. Never heard of Lloyds. Then again, i'm not a motor head either, so.... I just know that I really trust Paradise! Those guys are great!

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azwakekid

loyds marine has a new owner. its that guy vince that you have been talking to. he is very knowledgeable about boats. im sure he will get your boat done right the first time. good luck with the top end of your motor

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Dustin_360

jgouveia3-

Can you elaborate more on how you can hear the taping noise? The pinhole would have to be on the inside of the manifold to get water in the exhaust ports as in my case.

Just got my boat back today... hope it holds up.

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