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Exhaust manifold and risers ok? 454 MAG MPI's

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Old 06-21-2013, 05:33 PM
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Exhaust manifold and risers ok? 454 MAG MPI's (PICs inside)

Ok so just picked up another boat and am going to be honest I don't know a whole lot about the risers and mani's but noticed small seepage coming from the connection joint. I am assuming this has been happening for a period of time because its dry and just on there, it doesn't actually leak or have any issues when engine running. But wanted to see if this is common or sign things are going sour? Thanks for any input

1997 Baja 29 Outlaw w/ twin 454 MAG MPI's, 385's. Has roughly 320 engine run hours and 345 hour meter hours. No issues, no overheating or anything just asking the question.






Last edited by brapp21; 06-21-2013 at 07:06 PM.
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Old 06-21-2013, 08:08 PM
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You NEED to pull those risers and take a look at the inside of the risers and manifolds . I would bet the bank that you will see water leaking into the manifolds.
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Old 06-21-2013, 08:12 PM
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Just wondering but why would you assume water leaking into the manifolds just off those pics? I haven't had any issue or signs telling me so and the previous owner I just bought it from said it has been like that for years and he has not had any issues with them either.
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Old 06-21-2013, 08:16 PM
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Reason I am asking is because I don't want to drop $1,550 on a couple sets of manifolds and raisers right now if I don't have to. Thanks
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Old 06-21-2013, 08:17 PM
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In my experience, if there are signs of water leaking out, then there is a good chance it is leaking in. Not worth the risk of sucking water into the engine. I am not saying you need new manifolds, it may just need gaskets. I am just saying its worth checking into.
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Old 06-21-2013, 08:20 PM
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Thanks for the information. Is it common for the gasket between the mani and raisers to go bad vs. the actual parts themselves going out? It has been a freshwater boat its whole life.
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Old 06-21-2013, 08:50 PM
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Could just be the gasket leaking.. I pulled my last boats riser off (25ol w/454 may mpi) and it was spotless.
Buy some gaskets and start with the P side.. less involved to take off. Or you could get a snake camera and run it in the exhaust to see!

If you take it off, make sure you clean it well before putting back together.
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Old 06-21-2013, 09:03 PM
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I have replaced many riser gaskets in the past without there being a problem with the manifolds or risers. the gaskets are paper & are bound to go out sooner or later. Good time to clean any build up out of the passages. Randy
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Old 06-21-2013, 09:05 PM
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Also when you pull the raiser, drain the manifold first to avoid water standing in the raiser entering the engine.
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Old 06-21-2013, 09:12 PM
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Thanks guys, how hard is the SB engine to do? I can see the port side is going to be pretty straight forward. In order to not have to mess with it I may just have the local marine shop swap them and check the mani/risers. Don't have a lot of time and they can just come do it. Also if stuff went sour from the gasket swap then the mess would be on their hands not mine. But if both the SB and P sides are extremely easy I'll save my cash. Thanks
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