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Thread: DE-rusting risers/manifolds...

  1. #1

    Question DE-rusting risers/manifolds...

    I pulled my risers/manifolds off my motor, as I am getting a new one. Odie's Marine suggested I take them to a radiator shop to have them cleaned up a bit before they go on the new motor. They are fairly new and only need a little cleaning. What exactly do they do to them at a radiator shop to remove rust, etc, and where is a good shop to take them to? (outsides are painted black, and nice and shiny, so it's some trick they do on the inside???)

  2. #2
    Member fullbush's Avatar
    Join Date
    Feb 2010


    Myers its been my experience that mannys and risers usually don't outlive the motor, and 80% of the time a motors demise is because of the risers. Cast iron risers get pinholes just like aluminum, though you can't detect it there is a slow leak into your cylinders. Risers and Manifolds are about 700.00 a piece for aluminum ones I'm not sure what cast iron costs. Ask Odie I'm sure he'd concur

  3. #3


    I agree, but these are almost new and I am under the assumption they dip them in some kind of acid to clean up the insides a bit? Or something like that?

  4. #4
    Member GrizzlyH's Avatar
    Join Date
    Dec 2009
    Wasilla, AK


    I'm a 30 year ex mechanic now, but I never put a new engine in anyones car or truck without telling them to put a new radiator in it to make darn sure that new engine doesn't get fried prematurely. Cost of a radiator, $200 to $300. Cost of a new engine, $3500 to $6000.
    You do the math on that one. IMO, new cooling system for insurance. JMO of course.
    I can do the impossible right away. Be patient, miracles take me a bit longer.

  5. #5


    Myers - Did your engine have fresh water cooling or raw? How long were the risers and manifolds on the engine? And if the engine was raw water cooled, did you flush the engine after each trip?

  6. #6
    Member Alaskanmutt's Avatar
    Join Date
    Apr 2006
    Anchorage Alaska


    They don't do the acid baths anymore. Now it is a hot soapy water solution and most likely ultrasonic vibrations to clean. Ahhh the olden days when tanking meant hot acid baths..... The smell of sulphuric acid in the morning.

    Call Anchorage Drag Bike. I am sure they could hook you up and they have fair prices.
    2000 Bayliner Ciera Express 2452
    5.0 Mercruiser Alpha 1

  7. #7


    Yep, no more acid. Apparently they don't even get the rust off with the water, yet it can take the paint off??? Either way, they are not that old and don't need replacing. I sprayed some corrosion inhibitor, stuff that is used for electrical parts, in and around the ports and that seems to be enough to spiff them up.

    I have had a riser years ago plug and melt the rubber boot due to it rusting apart and stopping the flow. Also, had manifolds crack due to cold weather. It's important to flush the motor with the garden hose after each trip and pull the plugs out occasionally to get the grit out that builds up in them.


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