Manifold bolt rust

Discussion in 'General Maintenance/Repair Questions' started by jmauld, Aug 5, 2022.

  1. jmauld

    jmauld Well-Known Member GOLD Sponsor

    Jun 9, 2020
    Carolina Beach
    2010 Sundancer 390
    2016 Sea Hunt Ultra 211
    Twin 8.1l of gas guzzling iron
    I have done two of my four manifolds so far, and I removed the third one last night. This one had a single bolt with rust on the shaft of the bolt and when I removed it, there was a small amount of water in the bolt hole. (I wasn't brave enough to taste the water since my fingers were so greasy)

    How worried should I be about this?
     
    Nater Potater likes this.
  2. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 EC
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin 546s Plotter
    454 Crusaders
    Normal. Use thread sealer on threads during reassembly.
     
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  3. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx 502 mag
    2005 Baja 242 islander 496
    502 mpi Bravo 1
    496 mag B1
    How so? There're blind holes
     
  4. jmauld

    jmauld Well-Known Member GOLD Sponsor

    Jun 9, 2020
    Carolina Beach
    2010 Sundancer 390
    2016 Sea Hunt Ultra 211
    Twin 8.1l of gas guzzling iron
    The install guidelines do say to use sealant on the bolt threads. Which seemed odd to me.
     
    Last edited: Aug 5, 2022
    Nater Potater likes this.
  5. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx 502 mag
    2005 Baja 242 islander 496
    502 mpi Bravo 1
    496 mag B1
    Good idea, prevents rust and keeps them from backing out.
     
    Nater Potater likes this.
  6. jmauld

    jmauld Well-Known Member GOLD Sponsor

    Jun 9, 2020
    Carolina Beach
    2010 Sundancer 390
    2016 Sea Hunt Ultra 211
    Twin 8.1l of gas guzzling iron
    Which gets me back to my concern of why this one bolt is rusted. 1 out of 24 bolts so far.
     
  7. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 EC
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin 546s Plotter
    454 Crusaders
    My Crusader elbow studs have threads that are open to the water jackets and require thread sealant and the stud threads. I also put anti seize on the studs to aid in future removal of the elbows and fresh water adaptors.
     
    Nater Potater likes this.
  8. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx 502 mag
    2005 Baja 242 islander 496
    502 mpi Bravo 1
    496 mag B1
    He's talking manifolds not elbows. Whatever.
     
  9. Soulshine

    Soulshine Well-Known Member

    Sep 25, 2016
    Seneca Lake, NY
    '83 SRV 360 Express
    Twin Merc. 454
    Mercruiser Perfect Seal is great stuff.

    Not only is it a thread sealant, but acts as an anti size compound as well.
     
    OllieC and techmitch like this.
  10. OllieC

    OllieC Well-Known Member SILVER Sponsor

    Mar 11, 2013
    ‘Sconnie
    Sara Belle
    2005 Weekender 215
    Mercruiser 5.0 mpi, Bravo III
    ..and it’s like mustard and seems to get everywhere.
     
  11. Nater Potater

    Nater Potater Well-Known Member GOLD Sponsor

    Oct 19, 2020
    Southwest Idaho
    1992 300DA Sundancer
    Twin Merc Alpha I Gen II I/O's with 5.7 V8's
    upload_2022-8-7_14-52-3.png
     
    Jus Cruisin likes this.
  12. Hoplite808

    Hoplite808 Active Member

    316
    Jan 11, 2022
    Honolulu, HI
    1996 Sea Ray 270 Sundancer
    Mercruiser 7.4 LX MPI EFI (Gen. V)
    The water behind that and several other bolts is normal. Several of the holes are deep enough to enter the water jacket of the block. All that water was, was a cooling fluid that didn't completely drain out prior to removing that bolt, absolutely nothing to worry about. Before reassembly use a tap and die to clean the threads of the hole and bolt so you can get a proper torque reading during reassembly. Use thread sealant not anti-seize during reassembly. The lithium in anti-seize is a base metal and with the contact to the water jacket can expedite electrolysis. The Teflon in the thread sealant will be adequate to act as an anti-seize plus its what is advised in the manual.
     
  13. scoflaw

    scoflaw Well-Known Member

    Aug 10, 2011
    cape cod mass, cape coral fl
    1999 Powerquest legend 260 sx 502 mag
    2005 Baja 242 islander 496
    502 mpi Bravo 1
    496 mag B1
    Nope, none of those holes reach a water jacket.
     

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