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You said the engine hydrolocked, but then you say that you pulled all the plugs and there was no water in the cylinders. It sounds like you could have multiple issues. The Merc Gils were very susceptible to reversion, especially in the earlier years before they changed the risers.
If you've got 80psi and are not seeing any leaks, then the manifolds are fine. They only see about 3psi at idle.
Originally Posted by tcelano
(Post 3574152)
I'd bet the riser/elbow went bad. What did the manifold/riser gasket look like?
If not those, then the only other answer is reversion. You could have hit some harmonic holding it at 1500 that sucked water down, but the exhaust pressure kept it from entering the exhaust valve. Once you dropped back to idle, there would have been much less exhaust gas velocity coming out of the cylinder, with the exh valve staying open longer, allowing it to flood. |
did you spin it over with the plugs out ?? should have...sounds weird to hydro-lock while running like that ??
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Originally Posted by Griff
(Post 3574317)
You said the engine hydrolocked, but then you say that you pulled all the plugs and there was no water in the cylinders. It sounds like you could have multiple issues. The Merc Gils were very susceptible to reversion, especially in the earlier years before they changed the risers.
If you've got 80psi and are not seeing any leaks, then the manifolds are fine. They only see about 3psi at idle. It is a dry joint. Water passes between via a hose. Agree with Griff, odd that you did not find any water in the cylinders. |
Merc had a bulliten out awhile back on running their motors on a garden hose. They recommended @ 1,200 RPM and not to have a ton of water pressure coming out of the hose. When you backed off the lower RPM and high water pressure could have reverted water. Are you sure it didn't just drop a couple of cylinders and die?
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Crank it over with no plugs in it and see if the noise is still there and if it turns over smooth. It sounds to me like something else let loose.
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Originally Posted by Griff
(Post 3574317)
You said the engine hydrolocked, but then you say that you pulled all the plugs and there was no water in the cylinders. It sounds like you could have multiple issues. The Merc Gils were very susceptible to reversion, especially in the earlier years before they changed the risers.
If you've got 80psi and are not seeing any leaks, then the manifolds are fine. They only see about 3psi at idle. It is a dry joint. Water passes between via a hose. |
Originally Posted by ezstriper
(Post 3574339)
did you spin it over with the plugs out ?? should have...sounds weird to hydro-lock while running like that ??
Originally Posted by blue thunder
(Post 3574618)
Crank it over with no plugs in it and see if the noise is still there and if it turns over smooth. It sounds to me like something else let loose.
I'm just gonna tuck my tail between my legs and pull the motor out, and tear it down. I'd rather it be right then questionable, besides I got all winter. |
Stuck exhaust valve?
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Originally Posted by Eliminator28
(Post 3574798)
Turned it over with the plugs out, and manifolds off, and it makes an ugly thunking noise.
I'm just gonna tuck my tail between my legs and pull the motor out, and tear it down. I'd rather it be right then questionable, besides I got all winter. |
Originally Posted by tcelano
(Post 3574876)
Stuck exhaust valve?
When I get it apart I'll post up some pics so all you guy's can have some fun at my expense :drink: I'm trying to have a sense of humor....:cool: |
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