Chevy 350

Discussion in 'Powerboats' started by mikealston2428, May 25, 2012.

  1. mikealston2428
    Joined: Jul 2011
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    mikealston2428 Senior Member

    Hi All,

    I have a question.

    I have a chevy 350 inboard with a Mercruiser stern leg.

    The motor has a header tank (I think this is what it is called) with a heat exchanger.

    What I want to know is, can I run the motor with out the leg in the water or connected to a water hose.





    If I don't put the leg in gear (leave in in neutral) and only run it for a short time so the water running thru the motor doesn't start getting to hot.

    The reason I ask this is because I would like to be able to give the motor a quick warm up at home on the trailer before heading for the boat ramp.

    Cheers,
    Mike.
     
  2. IMP-ish
    Joined: Jan 2011
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    IMP-ish powerboater

    Alpha drive? Get a "pair" of outdrive muffs for $15 that you hook a hose to. If you run the engine with the outdrive dry you run the risk of damaging the impeller in the outdrive. It won't be lubricated by the water but will still be spinning. It can be damaged in a couple minutes so it won't pump as well.
     
  3. Frosty

    Frosty Previous Member

    And --dont run it with the leg fully up. Must put the leg down.
     
  4. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Yes, you can run the engine with the drive down and in neutral for a short time.

    To define "short time": if there is a smell of burning rubber, that means the exhaust hoses are smouldering because they don't get water from the discharge ports behind the risers.
    The header tank and heat exchanger are there to prevent internal engine corrosion and allow a more efficient operating temperature. They are not there to facilitate dry running.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The drive leg's impeller will self destruct in very short order without water. I change plenty of them, because owners think they have something magical in their outdrives.
     
  6. midnitmike
    Joined: Apr 2012
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    midnitmike Senior Member

    Mike,
    I suppose I can understand the desire to warm up the engine prior to making your trip to the boat ramp, but what I can't quite grasp is why you would consider doing this without taking even the simplest precautions. You've gotten the best possible advice already, so I won't add anything to the list. I'm just curious as to why you think this is a viable option?

    MM
     
  7. Frosty

    Frosty Previous Member


    What are you saying? this is incorrect advice, the rubber impellor pump is in the leg above the gearbox that turns with the engine.

    Nothing to do with exhaust rubbers.
     
  8. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    You can't warm up engine without water without frying it. It is that simple enough.

    Some parts will get warm, some hot and some will melt. And you will only know which when you rebuild engine if that is even possible.
     
  9. mikealston2428
    Joined: Jul 2011
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    mikealston2428 Senior Member

    Thanks guys,

    Seems most of you are off the opinion this was a silly question.
    I was 99% sure I should definitely not do it.

    I will give you abit of back ground as to why I asked.

    I as many boat owners don't have the space at home to store my boat so have been lucky enough to find a great mate with space and willing to let me store my boat at his house.

    When I have not used the boat for a couple of weeks I have to take the top off the carburettor and pour a small amount of petrol in the get it started and then warmed up, this understandably get others waiting for me to get off the ramp upset.

    I have a pair of earmuffs that I warm the motor up at my mates place before heading off.

    When I am having a early morning start I cant fire the motor up at my mates place and wake everyone up at 4:00 in the morning as you could imagine that would not go down to well.

    I guess I will have to put up with the abuse at the ramp, I don't like upsetting fellow boaties but don't really have a choice.

    Thanks for the advice.

    Mike.
     
  10. Frosty

    Frosty Previous Member

    It should have an accelorator pump. Pump the throttle a few time maybe up to 10 to squirt fuel in.

    These big ******* need a lot of fuel to fire up.
     
  11. IMP-ish
    Joined: Jan 2011
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    IMP-ish powerboater

    Any friends who are mechanics? Bet you can get it to start up easier without having to pour gas in. Never had to do that on any of my boats.
    Should turn over in a few seconds once you get the hang of feathering it right. My 350s started as easy as any of my engines. Warm up for 1-2 minutes is all it takes to idle smooth. Adjusting the carb some people have it and some people can't get it right. I'm not great at spotting carb problems, got a friend with the touch and he cleaned up and adjusted my carbs in an hour better than I had ever got them.

    Also want to add one bit - once had a guy helping me and he started both engines before I noticed no water. Ran for 30 seconds to a minute dry. Didn't kill the impellers. Once in a while you luck out and they are fine. Was launching, and went ahead and it ran the whole season with no temp problems. Now, DON'T do it because chances are good you will hurt them. Only added that because once in a while you luck out.
     
  12. midnitmike
    Joined: Apr 2012
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    midnitmike Senior Member

    Hi Mike,
    OK that explains the situation a bit better. Can we assume that you've already tried Frosty's advice about pumping the throttle a few times, it still wouldn't start, and so now you're forced into dumping gas down the carb? If so you might want to check out that same accelerator pump to see if it's functioning properly. It could be the choke is stuck open, so the only way it will start when it's cold is with a over rich fuel air mixture.

    Whatever the cause it sounds like a few minutes of troubleshooting this malfunction is in order.

    MM
     
  13. Frosty

    Frosty Previous Member

    But they were submerged and lubricated by water, not pumping is another issue.
     
  14. IMP-ish
    Joined: Jan 2011
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    IMP-ish powerboater

    No, it was in the storage building 500' from the water. Didn't have spare impellers. I went ahead with launching anyway. Ran all day and all season with no temperature problems. It did have green antifreeze in the rest of the system from being winterized, but the water pumps in the drives would have been dry or dry within a second with no muffs on them, I think. I lucked out that time.
     

  15. mikealston2428
    Joined: Jul 2011
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    mikealston2428 Senior Member

    I have tried pumping the choke a heap of times but no fuel skirts in to the carb, sounds like i need to have this looked at.

    On a different note the last trip out the motor run terrible, it was blowing real black smoke and there was black sot floating on the water behind the boat from the exhaust, never done this before.

    The engine seemed really choked up, took awhile for engine to clear it self and rev high again, not sure if the timing has gone out and or the carb needs adjusting.

    Real frustrating as up until now it as run great.

    Mike
     
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