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  1. #1

    Default Help with 4.3L MPI draining

    Pictured here is the engine I have. I want to switch this year and use the quick drain single knob to drain the system then fill it manually with the pick antifreeze. For whatever reason I am always suspect as to how much gets in when I suck it through the intake at the sterndrive. Anyway, was going to drain with know and pull plug on thermostat to make sure water out. Need to know which tube to pull off to fill with pink stuff? I think its the large tube on left of thermostat?
    Do I fill it til pink stuff starts coming out of thermostat itself where big tube hooks on? Meaning it has filled the entire block and come full circle? Thanks for the help. Click image for larger version. 

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  2. #2
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    4,337

    Default Re: Help with 4.3L MPI draining

    Personally I would remove the "quick crack" system and go back to plugs.
    Open the blue knob and verify atleast 3.5 - 4 gallons come out. If you suspect it did not all drain, remove the block quick connects and probe , remove the manifold hoses at the bottom to verify draining
    Remove the large hose to the left and pour the A/F in until it comes out the therh housing, reconnect hose. Remove the 2 hoses that go to the bottom of the manifolds, pour AF in until it comes out the exaust, reconnect hoses
    Remove the drain plug at the raw water pump

  3. #3

    Default Re: Help with 4.3L MPI draining

    Quote Originally Posted by Bt Doctur View Post
    Personally I would remove the "quick crack" system and go back to plugs.
    Open the blue knob and verify atleast 3.5 - 4 gallons come out. If you suspect it did not all drain, remove the block quick connects and probe , remove the manifold hoses at the bottom to verify draining
    Remove the large hose to the left and pour the A/F in until it comes out the therh housing, reconnect hose. Remove the 2 hoses that go to the bottom of the manifolds, pour AF in until it comes out the exaust, reconnect hoses
    Remove the drain plug at the raw water pump
    I am with you , just 2 questions
    1. How easy to get to are the 2 hoses that hook to the block?
    2. when you say remove drain plug at raw water pump, do you mean just to drain it or leave it out? where is raw water pump? same as circulating pump?
    Thanks for the help

  4. #4

    Default Re: Help with 4.3L MPI draining

    Also
    I have a 2008 Mercruiser 4.3L MPI alpha drive with the single point drain. Anyone know how many blue drain plugs I should be undoing?

  5. #5
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    4,337

    Default Re: Help with 4.3L MPI draining

    This is assuming you have a standard system
    therm housing, each side of the block, fuel cooler, raw water pump(Bravo ) each manifold
    A single point or 3 point system does not use blue plugs except maybe at the T housing
    Need to remove the block quick connect and probe the holes
    Last edited by Bt Doctur; 10-21-2018 at 09:44 PM.

  6. #6
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    4,337

    Default Re: Help with 4.3L MPI draining

    This is from a V8 but very similar to the V6

  7. #7
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    10,196

    Default Re: Help with 4.3L MPI draining

    ..........................
    Quote Originally Posted by pharmacist25 View Post
    Pictured here is the engine I have. I want to switch this year and use the quick drain single knob to drain the system then fill it manually with the pick antifreeze. For whatever reason I am always suspect as to how much gets in when I suck it through the intake at the sterndrive. Anyway, was going to drain with know and pull plug on thermostat to make sure water out. Need to know which tube to pull off to fill with pink stuff? I think its the large tube on left of thermostat?
    Do I fill it til pink stuff starts coming out of thermostat itself where big tube hooks on? Meaning it has filled the entire block and come full circle? Thanks for the help.
    Click image for larger version. 

Name:	IMG_20120805_120319.jpg 
Views:	20 
Size:	50.2 KB 
ID:	18988
    Please take a few minutes and read this write-up. A great portion of it will pertain to what you are wanting to do, and it will explain why this should NOT be done!
    https://www.amazon.com/gp/customer-r...at_pdctrvw_srp

    .............................
    Quote Originally Posted by pharmacist25 View Post
    I am with you , just 2 questions
    1. How easy to get to are the 2 hoses that hook to the block?
    As Bt Doc says..... get rid of any single point drain, 3 point drain or quick drain system that uses hoses.
    Use a true Marine style petcock with a removable stop.
    Remove the stop and probe the drain ports.
    Just plain AIR will not freeze expand and ruin your expensive cast iron components!


    2. when you say remove drain plug at raw water pump, do you mean just to drain it or leave it out? where is raw water pump? same as circulating pump?
    On the Merc A drive, the seawater pump is in the drive..... actually, it is above the lower gear unit.
    The engine circulating pump is the belt driven GM style pump at the very front of the engine.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

    Please... no PMs! Post your questions on the forum.

  8. #8

    Default Re: Help with 4.3L MPI draining

    Quote Originally Posted by RicardoMarine View Post
    ..........................


    Please take a few minutes and read this write-up. A great portion of it will pertain to what you are wanting to do, and it will explain why this should NOT be done!
    https://www.amazon.com/gp/customer-r...at_pdctrvw_srp

    .............................
    Well I have the one pictured above with the alpha.
    So I need not worry about a raw water pump? I just need to undo hose to pump ion front of motor to pump right? along with others of course

  9. #9

    Default Re: Help with 4.3L MPI draining

    thanks

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