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  1. #1
    Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Engine Shutdown Precautions after a HARD RUN (Especially in cold water)

    This should be a discussion of "reasonable engine operation" techniques, especially in cool or cold water operation scenarios. Would especially like some input from others with extensive engine building experience:

    There's been a lot of discussion regarding "engine temperatures" and "cold water operation" lately. One item is often neglected in these discussions: Engine shutdown!

    In "non-bassboat" applications (let's just say general pleasure boats), the boat operator would, under most circumstances, be dropping to idle speed for at least a short period after a long run. No wake zones, docking the boat, trailering the boat, etc. will all require some period of engine idle.

    Hence, we don't discuss the need for an engine's temperature to "stabilize" after a hard run in cool or cold water- it's usually a "given" for MOST applications.

    However... in a bass application- it's a different story. Sometimes, the temptation to "fly in" to a spot at 75%-100% throttle, yank back to neutral and immediately shut down is overwhelming... especially when you just know that today's "big bass" is right there... waiting for you!

    At high RPM's... the poppet valve in ALL of our motors is controlling the flow of coolant. Flow is essentially "WIDE OPEN". Those of you running Smartcraft can attest to this... you see temps of 120+ at idle... and perhaps as low as mid-80's at WOT. Combustion chamber (internal) temps, however, are "screaming high" on a really hard run... and it's just common sense that you'd allow the engine to idle for at least 45-60 seconds before shutdown. This allows the temps to "stabilize"... especially before you trim the engine up in a cove, draining 50% or more of the coolant from the engine, and allowing it to "perk" while you fish....

    In all honesty... we put these engines through worse "thermal conditions" than many competition racers would! Long WOT runs, hard turns, low cooling temps (so far we're similar to racing....), and WHAM- turn the key off, trim the engine up, drain most of the coolant, and just let it sit there and PERK! OH... and we might be inclined to just fire it right back up a couple minutes later, trim it down, and before the cooling system has a chance to refill the block- go right back to WOT again!

    Then we wonder why we see "thermal events" in the lower (or upper) cyl's.......

    My recommendation: Don't just wait for the engine to warm up on cold starts- ALLOW TEMPS A CHANCE TO STABILIZE after a hard run- at LEAST 45-60 seconds before shutting down!

    This post is NOT directed at anyone in particular- it's meant to be INFORMATIVE- something that many might "glean information from". Tech's- engine builders- owner's alike... let's hear your thoughts! (You've now heard mine)
    Last edited by EuropeanAM; 05-05-2012 at 06:39 AM. Reason: Syntax Correction- VBulletin


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  2. Member Largemouthlou's Avatar
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    #2

    Re: Engine Shutdown Precautions after a HARD RUN (EuropeanAM)

    Great post!!

    It makes sence and is something I always try and do, whether it is my genorater, weed eater or boat motor!!! Maybe that is why I have more hrs at 0-1500 then other rpm ranges..

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    #3

    Re: Engine Shutdown Precautions after a HARD RUN (EuropeanAM)

    Hi Don. I understand exactly what you are saying. I had a recent thread asking how to add a temp gauge to my Pro XB for that very reason that you are talking about. Does it make sense then that after a WOT/hard run that we would idle the motor in neutral for the 45-60 seconds or bring the motor up to say 2500-3000 RPM in neutral to circulate more water and then shut down? A greater exchange of water would help stabilize the temperatures quicker? Your thoughts on this? Thanks.

  4. USAF and DOD retired Phoenix Jim's Avatar
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    #4
    I just bought a new puma with a pro xs. I got a five year warranty and Don!
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  5. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #5

    Re: Engine Shutdown Precautions after a HARD RUN (oldgeezer)

    <TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oldgeezer &raquo;</TD></TR><TR><TD CLASS="quote">Hi Don. I understand exactly what you are saying. I had a recent thread asking how to add a temp gauge to my Pro XB for that very reason that you are talking about. Does it make sense then that after a WOT/hard run that we would idle the motor in neutral for the 45-60 seconds or bring the motor up to say 2500-3000 RPM in neutral to circulate more water and then shut down? A greater exchange of water would help stabilize the temperatures quicker? Your thoughts on this? Thanks.</TD></TR></TABLE>

    Excessive RPM's in neutral are really not a good idea, under any circumstances. Some of the engines we deal with on this board WON'T allow you to exceed 1300-1500 RPM's neutral, without setting "Overspeed in Neutral Faults".

    IMO... it doesn't really matter that much whether you idle in forward, neutral, or even reverse. Perhaps... a wise approach when you see your future "honey hole" is to throttle back to idle "earlier"... approach that hole in "stealth mode" (might even help to prevent scaring everything off)... idle up to the spot in gear, shift to neutral for a few moments, and then shut down. You would have (hopefully) been at idle speed for 45-60 seconds... thus allowing the engine temps to stabilize.

    The whole key to what we're looking for is "controlled expansion and contraction of internal engine components"... which is critical in ANY internal combustion engine, but FAR more critical in 2-stroke engines (where the potential for severe failures from uncontrolled expansion/contraction is even greater, regardless of "brand" or "fuel delivery technology").



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  6. Member Jim Dunn's Avatar
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    #6
    I wouldn't shut down my diesel trucks without allowing them to cool down first. Turbo charger get smoking hot on a hard run.
    I got nothin

  7. Member Jim Dunn's Avatar
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    #7

    Re: Engine Shutdown Precautions after a HARD RUN (EuropeanAM)

    Can you make this a stickey?
    I got nothin

  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #8

    Re: Engine Shutdown Precautions after a HARD RUN (Jim Dunn)

    <TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jim Dunn &raquo;</TD></TR><TR><TD CLASS="quote">Can you make this a stickey? </TD></TR></TABLE>

    "This post will automatically sticky within the next three days".



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  9. #9

    Re: Engine Shutdown Precautions after a HARD RUN (EuropeanAM)

    That is a great point Don!! The only thing that I would add is: As soon as the engine is stopped whether you tilt the engine or not, the water begins to drain out of the engine. The Manufactures have designed it this way to prevent winter time freezing. Which makes the problem worst!! If you will touch the engine heads after you have stopped you will find that the engine is very hot!! I support your suggestion that we should idle for a few minutes to bring the temps down
    Another point is this condition will also dry out all the fuel and oil mix in the engine and make it very lean to re-start. I'm not suggesting that this will make it hard to start (although it will) but it will create premature wear on rings and pistons!! This is scarey stuff Don.........great point again

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    #10

    Re: Engine Shutdown Precautions after a HARD RUN (Wayne Worthy)

    I've seen motors with the loss of water flow and the depleation of cooling media through drainage the motor for a few seconds ( 30 or so ) will get hotter this is called the OVEN EFFECT. 99% of you guy's motors are thermostaticly controlled to reach safe target temps for proper sleeve expantion. How many horror stories have been told of cold seezing where an over zellos boater in cold ambient water temps or a steel sleeved engine was jumped on too quick BEFORE the steel sleeve has reached its full expantion size and the piston sticks. When all it would have taken was 1 to 2 minutes of a slow idle to allow the sleeve to get to the proper safe deminsion.The same for quick shut down, IMO I have always thought that its better to allow the cooling system to "catch up" and cool the hot parts and allow a gradual controlled cool down if it would be only 1 to 2 minutes...

    I've heard the old saying an outboard engine is nothing more than a hand grenade with the pin pulled and mostly in my business I see allot of this to be true with the continual abuse that High Performance engine are exposed to. These big HP per CI and continued high rpm toys we all enjoy take a heck of allot of abuse with only one gear, LOW. Just think how long your family car engine would last if it were turned 5500-6200 rpms or ran in LOW GEAR 90 % of its running life. My suggestion is to give them every chance to live with proper operating methods and encompass a huge dose of common sence , this could and will buy you more time, enjoyment on the water and save your wallet before that hand grenade goes boom...I tell people that our modified drag motors make MORE HP per Cubic Inch than an NHRA Pro Stock car motor and they are torn down after EVERY race session ....So don't expect the motor burning the candle at both ends to last like a new Chevy , they just don't enjoy that long of a life span , but care and the use of a brain cell can and will extend their life though...

    just my thoughts,
    Jay @ JSRE
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    #11

    Re: Engine Shutdown Precautions after a HARD RUN (JaySmithRacing)

    Not much at all to add to Wayne's, Don's and Jay's comments. All very important and pertinent to engine longevity and proper operation. Couldn't agree more.....

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    #12

    Re: Engine Shutdown Precautions after a HARD RUN (redline)

    One of the Mercury mechs at the ABA Natls a few years ago told me this same thing. He believed that the reason for the #6 failure on many bass engines was from not letting them idle. (water getting sucked it maybe) I have been doing this ever since and I consistenly watch the temp on my smartcraft while idling til shutdown. Excellent post!!!!!!!
    Dave Sheffield
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  13. Member mikepags's Avatar
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    #13

    Re: Engine Shutdown Precautions after a HARD RUN (Shef)

    great post.........

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    #14

    Re: Engine Shutdown Precautions after a HARD RUN (EuropeanAM)

    Don, You have covered this issue well.. I often am amazed at how well our OB's do hold up with the way we treat them day in and day out...I guarantee you our cars n' trucks couldn't take the same treatment and live very long....Guy's you just need to give them time to warm up and cool down and feed them good gas n' oil....Good post! Sherm

  15. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #15

    Re: Engine Shutdown Precautions after a HARD RUN (shermsmarine)

    Here's an example of what CAN happen if you DON'T follow these recommendations:

    http://www.bbcboards.net...perly



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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  16. #16

    Re: Engine Shutdown Precautions after a HARD RUN (EuropeanAM)

    Don don't think this would be a problem but after you put your boat on the trailer pull up the ramp stop and then put your factory Mercury cowling cover on after just shutting the engine off. Would this cause any heat related problems because all the vents are now covered. Would you recommend a cooling off time before the cover goes on? Thanks


    Modified by bassbama at 10:44 AM 5/1/2009

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  17. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #17

    Re: Engine Shutdown Precautions after a HARD RUN (bassbama)

    By the time you get your boat up the ramp, water drained, gear stowed, boat tied to trailer....

    I think you'll be safe to put the cover on it.

    The big concern comes from the engine "turning" when dis-similar metals have varied rates of expansion.



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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    #18

    Re: Engine Shutdown Precautions after a HARD RUN (EuropeanAM)

    Great post,,,,,especially as i only have 25.6 hours according to my check up....good info to have for my 250 pro xs
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    #19

    Re: Engine Shutdown Precautions after a HARD RUN (Hillsreels)

    I bet you could use a turbo timer.

    It is a device that allows you to shut the key off but the engine still runs for a selectable amount of time.


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  20. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #20

    Re: Engine Shutdown Precautions after a HARD RUN (chad0722)

    <table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by chad0722 &raquo;</td></tr><tr><td class="quote">I bet you could use a turbo timer.

    It is a device that allows you to shut the key off but the engine still runs for a selectable amount of time. </td></tr></table>

    Interesting thought.... though I suspect the "timer" would have difficulty distinguishing between a "regular shutdown" and an "emergency" (presenting some potential concerns)



    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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