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525efi Reversion??

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Old 12-13-2018, 06:30 PM
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Default 525efi Reversion??

I just completed a stock rebuild of a 525 Mark Boos @Precision Marine done the engine work. The engine has stainless Marine manifolds pressure tested good. Broken in on the Dyno with no issues. Installed in the boat after idling until the thermostat opened we checked the manifolds and found a small amount of water/dampness in the bottom of the exhaust manifolds. The risers are Stainless Marine risers and checked good when tested with water off the engine. Could this be a reversion issue? Any advice would be helpful.
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Old 12-15-2018, 03:49 PM
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Sounds like reversion. May not end up being a problem if you used inconnel exhaust valves and try to keep the engine off idle as much as practical. Things other than water leaks that could cause this would be cam incorrectly degreed or an exhaust valve not sealing entirely. I'd run it though and watch for more clues.

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Old 12-16-2018, 08:53 PM
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BT, I was thinking the same thing. A couple thoughts, we were running on a hose and the water was cold it could have been condensation as it was very damp air also. I also found a small exhaust leak between the manifold and the riser, according to stainless marine this will cause reversion also. I am going to change the gaskets, use sealant and see how it does. Yes I do have inconel valves, this is my first 525 and I may just be overly cautious.
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Old 12-17-2018, 01:33 AM
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Running on the hose or in the water?
If on the hose, is the boat sitting at the same angle as when it sits in the water at idle?? Bow being down slightly could make a difference.
Its possible that it could just be some condensation as well.
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Old 12-17-2018, 06:38 AM
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Originally Posted by Griff View Post
Running on the hose or in the water?
If on the hose, is the boat sitting at the same angle as when it sits in the water at idle?? Bow being down slightly could make a difference.
That is a really good point! I've been court out by that and bent a push rod......
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Old 12-17-2018, 07:56 AM
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Originally Posted by Lil Mick View Post
BT, I was thinking the same thing. A couple thoughts, we were running on a hose and the water was cold it could have been condensation as it was very damp air also. I also found a small exhaust leak between the manifold and the riser, according to stainless marine this will cause reversion also. I am going to change the gaskets, use sealant and see how it does. Yes I do have inconel valves, this is my first 525 and I may just be overly cautious.
I believe the joint betw the riser and manifold on your setup is dry so that gasket leaking shouldn't result in water reversion.
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Old 12-17-2018, 10:03 AM
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The leak will cause reversion not because the water is in the joint but it’s pulling more vacuum through the riser
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Old 12-17-2018, 10:17 AM
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How does a leaking riser gasket create more vacuum?
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Old 12-17-2018, 10:38 AM
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Originally Posted by blue thunder View Post
How does a leaking riser gasket create more vacuum?
When I installed bungs in my headers I pulled the plug off of one that’s about 14” up from where the water mixes and it still soaked my hand. I put the plug back in and checked it later with the engine off and it was dry and sooty.
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Old 12-17-2018, 01:01 PM
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The exhaust escaping sooner pulls more vacuum up the tailpipe. I had it happening with a leak at riser gasket on stand. Eddie young also told me this was likely the reason and it was.
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