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Put throttle into reverse while going fast

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Put throttle into reverse while going fast

Old 05-06-2019, 10:16 AM
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I am not sure at what speed a prop will turn an engine, but I bet it is a lot slower than many would think. Engines are designed to have very low friction so they can be efficient. A big honkin' V8 can be turned with a socket wrench on the flywheel nut. Why wouldn't an outboard be able to be turned by a 15-17" wide three or four blade propeller? That is plenty of torque to turn a stalled engine. If that stalled motor's gear is in reverse and the boat is still moving forward that water flowing over the prop will turn the prop, which while connected to those gears and shaft and engine will certainly turn that engine in the opposite direction it is designed to rotate. Now instead of fuel and air coming in the intake valve and exhaust out the exhaust valve, the engine will be sucking in through the exhaust and trying to exhaust out the intake. Once water gets into that cylinder it will not compress and a bent rod is a likely consequence.

Don't worry, took me a little while to visualize it too. I had to see the engine being stalled and everything from the crankshaft to the prop being solidly connected without clutches to understand it being capable.
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Old 05-06-2019, 10:24 AM
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When I was a kid I had an old V-4 Johnson 80 (or 85?) with electric shift. Didn't have the correct shifter so had a morse control and a 3 position toggle switch unpside down under the console. Push if forward/Neutral/reverse engaged by pushing the toggle forward or backward. Got is some choppy water while running about 20-25 mph and my cooler slid back under the console, shifting from forward to REVERSE. Motor kicked up, blew water into the boat and the boat coasted to a stop. I figured I had trashed the lower unit....slowed the motor down, shifted back to Forward...and continued on my trip.

I didn't put my cooler under the console after that.

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Old 05-06-2019, 12:30 PM
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Originally Posted by carbo View Post
There is no "yamaha system" that shuts a motor off for any reason. Reduction in RPM for things yes but will never shut motor off.
Not true. If the DTS system detects the shift actuator and shift lever out of agreement, the affected engine will shut down, flash the LED on the binnacle and throw code on the display. If itís not a hard fault, turning the battery switch off, then on might reset it.

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Old 05-06-2019, 12:41 PM
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Originally Posted by scooperfl View Post


Not true. If the DTS system detects the shift actuator and shift lever out of agreement, the affected engine will shut down, flash the LED on the binnacle and throw code on the display. If itís not a hard fault, turning the battery switch off, then on might reset it.

On the fly by wire, if it shuts the engine down will it put the gear case in neutral as well so there would be no chance of motor spinning backwards...asking for a friend
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Old 05-06-2019, 12:48 PM
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Old 05-06-2019, 02:32 PM
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Originally Posted by Vantaredoc View Post
On the fly by wire, if it shuts the engine down will it put the gear case in neutral as well so there would be no chance of motor spinning backwards...asking for a friend
I think i remember reading that at some point Yamaha added a feature to minimize the possibility of throwing one in reverse at speed.

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Old 05-06-2019, 02:45 PM
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Originally Posted by scooperfl View Post


Not true. If the DTS system detects the shift actuator and shift lever out of agreement, the affected engine will shut down, flash the LED on the binnacle and throw code on the display. If itís not a hard fault, turning the battery switch off, then on might reset it.


I do stand corrected in this situation. I'm so used to telling people in normal running situations with overheat or fuel issue or oil pressure problem it won't shut motor off it will just reduce rpm and alarm. I usually cringe when they tell me they got a "no oil" alarm and the computer shut off the motor.....Eh....ouch.
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Old 05-06-2019, 05:41 PM
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My manual states with regard to high idle speeds that while the shift lever will work, gear shifting will not occur until engine speed has reduced to a speed where actual shifting can occur. Wouldn't this apply where the shift to reverse occurs at speed?
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Old 05-06-2019, 05:48 PM
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My dad put the boat in reverse while cruising at 25knots...the motor bent a connecting rod as water forced up the exhaust and through an open exhaust valve. 2007 Yamaha F250 3.3L
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Old 05-06-2019, 05:51 PM
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Originally Posted by Pineapple Express View Post
My dad put the boat in reverse while cruising at 25knots...the motor bent a connecting rod as water forced up the exhaust and through an open exhaust valve. 2007 Yamaha F250 3.3L
You should tell your dad you read on THT this wasnít possible so it didnít happen.
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Old 05-06-2019, 06:03 PM
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Another reason to buy a g2 .
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Old 05-06-2019, 06:47 PM
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I am sooooo confused as to how this is even a discussion. I put 400 plus hrs on my outboards each year (and have done so for many years) and have never....ever...had to slam them into reverse when doing anything over idle speed. Maybe some need to either pay more attention to their conditions or walk away from boating all together.
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Old 05-06-2019, 09:37 PM
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Originally Posted by on deck View Post
I am sooooo confused as to how this is even a discussion. I put 400 plus hrs on my outboards each year (and have done so for many years) and have never....ever...had to slam them into reverse when doing anything over idle speed. Maybe some need to either pay more attention to their conditions or walk away from boating all together.

A few years ago I slammed the engine into reverse from 35 -38 mph in a sudden jerk on my Optimax. It made a horrendous clunk and the motor shut off.

Gulped, put into nuetral and she fired and everything was groovy.

Blue bird day, flat as a mill pond....all of a sudden right off the bow and I mean RIGHT in front of me was the start of my estimate of 80 or so feet of Blue Whale surfacing.
Thing just started surfacing right in front of me. We got spray on the windshield. I can't believe I didn't hit it. I about shit my pants.
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Old 05-06-2019, 09:52 PM
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Originally Posted by on deck View Post
I am sooooo confused as to how this is even a discussion. I put 400 plus hrs on my outboards each year (and have done so for many years) and have never....ever...had to slam them into reverse when doing anything over idle speed. Maybe some need to either pay more attention to their conditions or walk away from boating all together.
I wonder what the air is like up on that pedestal you are preaching from....lol
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Old 05-07-2019, 03:36 AM
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Has the OP's concern(s) been addressed ? Or has this thread run down a 'rabbit hole'.
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Old 05-07-2019, 03:41 AM
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I’d guess the hounds are still chasing his concerns
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Old 05-07-2019, 04:02 AM
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Originally Posted by mkalink View Post

You as with the others are wrong it will not reverse the direction and fill the motor with water. Even if for some reason it did reverse the pump wonít work in reverse.
sorry dude , not trying to offend you but you are Way Wrong... please no one listen to this poor advice
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Old 05-07-2019, 08:42 AM
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Since it probably did get lost and I was substantially to blame... I think the OP got good advice to immediately change the oil in both the engine and the lower unit, and check the lower for signs of metal. I would also run gently the first time out and take it in if there are continuing signs of problems.

It is, theoretically, an insurance claim if the motor is trashed. The longer you wait the harder this will get, though.
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Old 05-07-2019, 09:57 AM
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Originally Posted by mkalink View Post

no your wrong this cannot happen the motor can only turn in one direction. Nothing that happens in the lower unit can spin the motor n the opposite direction. The water pump wonít even work if run in the opposite direction. Iím not doubting you got water in your cylinders but it did not get pumped in from you engine turning backwards.
Its not the water pump that pumps the water, the water goes up through the exhaust either from the sudden stop that the back wash is forced up through the exhaust, but I donít know if the motor will actually stop rotating forward and completely reverse its spin from a prop in reverse. But if it can then it would it suck water into cylinders.
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Old 05-07-2019, 01:33 PM
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Originally Posted by HarvestTime View Post
sorry dude , not trying to offend you but you are Way Wrong... please no one listen to this poor advice
I don’t think so and if you had a clue you too would know that water across the prop cannot and will not reverse the engine and suck water into the cylinders. I am trying to offend the clueless. Water is ingested through the exhaust by washing up through caused by the sudden slowing or stopping. This is my point and saying the engine reversed direction and pumped my cylinders full of water can’t happen.
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