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  1. #1
    Cadet
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    Nov 2013
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    Default Bad intake manifold? or?

    Just put a brand new rebuilt 351W long block in my boat. I fired it up for the first time, ran it less than 2 minutes, and the oil is already turned to choc. milk. That's a bunch of water in a short period of time. How likely is it a bad intake manifold? I did use the old intake manifold off the old engine. I thought it looked fine so I just cleaned it up and bolted it on the new engine. I put all new marine gaskets and followed proper torque procedure. Guess I should have had it checked. How much should it cost to have it magnafluxed? Who does that sort of thing?
    TIA

  2. #2
    Senior Chief Petty Officer
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    Default Re: Bad intake manifold? or?

    Welcome to iboats!

    Like so many question from new people we get on here...the first thing I will say to you is; you have not provided enough info for us to begin making a diagnosis. It would be pure speculation.

    My first question for you would be, did you remove, repair, replace or in any way modify or manipulate the exhaust system on the engine?

    What made you take notice of the milkshake oil in only two minutes? What was your break in procedure?

    When you R&R'd the heads and manifold, were the mating surfaces properly prepared.

    Did you use expensive, quality intake manifold gaskets, and did you use an expensive quality torque wrench that had been calibrated?

    Did you assemble/rebuild the engine, or was it a crate purchase? Online or in person? Warranty? Have you even drained the engine to get the water off the bearings? Are you in salt or freshwater? Is the engine raw or freshwater cooled? What year is the block? Was it a "marine" designated engine you installed, or perhaps one from a supplier who deals in automotive engines?

    Lots and lots of questions I could ask you to get to the bottom of your issue.
    Last edited by Silly Seville; November 14th, 2013 at 09:20 AM.

  3. #3
    Captain AllDodge's Avatar
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    Default Re: Bad intake manifold? or?

    Quote Originally Posted by jackgm View Post
    Just put a brand new rebuilt 351W long block in my boat. I fired it up for the first time, ran it less than 2 minutes, and the oil is already turned to choc. milk. That's a bunch of water in a short period of time. How likely is it a bad intake manifold? I did use the old intake manifold off the old engine. I thought it looked fine so I just cleaned it up and bolted it on the new engine. I put all new marine gaskets and followed proper torque procedure. Guess I should have had it checked. How much should it cost to have it magnafluxed? Who does that sort of thing?
    TIA
    to iboats

    Who rebuilt the engine?

    While magnetic particle inspection is useful in finding hairline cracks this is not your current issue. A hairline crack would not flow water that fast into the crankcase.
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  4. #4
    Chief Petty Officer
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    Nov 2007
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    Medford, Long Island NY
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    571

    Default Re: Bad intake manifold? or?

    You've been given quite a few questions to answer before a true diagnosis can be made. My first reaction is to join Silly Seville in questioning the exhaust manifolds and risers. Were they checked? Are their mating surfaces clean and flat? Did you use the proper riser gaskets? (There are variations, depending on the exhaust-cooling arrangement.) You need to do some checking and post some more information and photos, if possible. First, get the water and oil out immediately, replace the oil filter and oil, spray or squirt oil in the cylinders, crank the engine a few time with the coil wire disconnected (if the boat's out of the water) to circulate some fresh oil. Hy

  5. #5
    Commander thumpar's Avatar
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    Default Re: Bad intake manifold? or?

    Pressurize the cooling system side and see what is leaking.
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  6. #6
    Cadet
    Join Date
    Nov 2013
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    Cool Re: Bad intake manifold? or?

    Ok, I got it! Your right, the intake is fine! The oil cooler was shot! Installed a new one and presto-bamo, problem solved. Thanks

  7. #7
    Chief Petty Officer
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    Jul 2012
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    444

    Default Re: Bad intake manifold? or?

    So my curious question is, why did you replace the engine in the first place?

  8. #8
    Cadet
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    Nov 2013
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    Default Re: Bad intake manifold? or?

    Had issues with both heads and Didn't know how much saltwater was in the engine for how long. Thought it would be just plumb dumb to only do the top end of a 37 year old salt water cooled engine that has been full of salt water since before I got it.When I go fishing, I'll take this boat 20-30 miles offshore. It was a free boat to begin with, now I have about 3k invested in it and it has a brand new motor. Thanks

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