Question about whether to leave boat in drive or not

[Mark Harvey]

I am new to boating this season and have a newbee question, well two of them. First question is, do I leave the boat in drive or neutral when I am not using it and it is left at the dock for a few days at a time? I have been and here is where I think I may be causing my own issues I’ve been chasing and maybe not. Second question is about carbs, specifically a mercarb. I have been putting it in drive but not thinking about it, I have been putting it at wot and leaving it there for days. I did check today and my accelerator pump is working fine, as I’m chasing a bog under acceleration while trying to plane up that’s worse the first time, as well as rough idle and smoke at startup for a bit 5-10 sec. Sorry the question. By leaving the throttle shoved all the way down, what happens due to the accelerator being left wide open?

 

[Paintman1960]

I gotta ask, why not leave it in neutral.
I never heard of anyone doing what you are doing ,

 

[Rick Stephens]

Do like you would a car. Motor is the same.

Yours sounds like it needs a carb kit or clean filters. Nice idea to do a compression check on a new to you boat motor.... or car motor for that matter. Gives you a baseline.

 

[achris]

...I have been putting it at wot and leaving it there for days..... By leaving the throttle shoved all the way down, what happens due to the accelerator being left wide open?

You leave the inside of the manifold completely open to any moisture in the air, and that moisture will settle on the intake valves, corroding them nicely.
The diaphragm in the accelerator pump will be at full stretch, leading to its early demise.

Your 3 litre boat engine is essential a car engine. Would you do this to your car engine?

Chris......

 

[Mark Harvey]

I gotta ask, why not leave it in neutral.
I never heard of anyone doing what you are doing ,

Someone had mentioned to me it was a bad idea to let the prop free spin in the water for extended periods while away from the boat. This is why I’m now asking on here. In case I have been doing it wrong.

 

[Mark Harvey]

Do like you would a car. Motor is the same.

Yours sounds like it needs a carb kit or clean filters. Nice idea to do a compression check on a new to you boat motor.... or car motor for that matter. Gives you a baseline.

Thanks for your advice. I have been chasing this issue all summer long. Bought the boat in June. Have done a compression test, 150psi in all 4 cylinders, new fuel water separator filter, new cap and rotor, plugs and wires, new fuel pump, and have checked all filters now except the anti siphon valve . Yesterday I tested the accelerator pump for two shots of fuel. That’s when it dawned on me what I was actually doing by leaving it in drive but all the way down like I was doing. I was curious then on what happens inside the carb by my careless over thought.

 

[Mark Harvey]

You leave the inside of the manifold completely open to any moisture in the air, and that moisture will settle on the intake valves, corroding them nicely.
The diaphragm in the accelerator pump will be at full stretch, leading to its early demise.

Your 3 litre boat engine is essential a car engine. Would you do this to your car engine?

Chris......

I will not be leaving it in drive any longer. Rookie mistake. I never really thought of the mechanics behind what I was doing, just that I was stopping the prop from free spinning in the water.

 

[achris]

... just that I was stopping the prop from free spinning in the water.

That's not going to hurt anything. The entire housing is filled (or should be) with gear oil.

I do drop the engine into reverse gear as I'm shutting it down when I'm fishing, but that's still with the throttle set at idle. It stops the prop spinning in the wind, so if one of my moron mates drags his line across the prop, it's not going to get wound in.

Chris.......

 

[achris]

Someone had mentioned to me it was a bad idea to let the prop free spin in the water for extended periods while away from the boat.

I can't for the life of me work out how it's a bad idea. ¯\_(ツ)_/¯

 

[Mark Harvey]

I can't for the life of me work out how it's a bad idea. ¯\_(ツ)_/¯

I remember dad always put his outboard in drive after he shut it off, but a 9.9 is not like a 3.0. I’m going to stop doing it and see if it changes anything. Thanks for you advice!

 

[Eric 3.7LX Alpha 1]

My 15 hp Mercury 4 stroke manual recommends putting it in forward when trailering to prevent the prop from spinning freely. Will it cause any damage if left to spin in the wind, I doubt it, but that is what it says. I would not put my sterndrive in gear while trailering or left sitting on the trailer.

 

[Mark Harvey]

My 15 hp Mercury 4 stroke manual recommends putting it in forward when trailering to prevent the prop from spinning freely. Will it cause any damage if left to spin in the wind, I doubt it, but that is what it says. I would not put my sterndrive in gear while trailering or left sitting on the trailer.

May I ask why you wouldn’t for my curiosity? I plan to stop putting mine forward now that I realize I shouldn’t. Bought the boat in June, used with no manuals so I really do appreciate everyone’s opinions. I’ve learned a lot over the summer going over this boat lol

 

[achris]

My 15 hp Mercury 4 stroke manual recommends putting it in forward when trailering to prevent the prop from spinning freely.

Having stripped and built many gearboxes and drives, there is NO WAY a free spinning prop can cause any internal damage. I suspect it in the manual to stop there being a perception of someone being hit by a spinning prop... (Although I still can't see how that would happen when the boat's being trailed down the freeway at 100km/hr)... Maybe it's to stop rubberneckers from being distracted.

Chris.......